Description
Risk mitigation occurs after the risk assessment phase is complete. Risk mitigation encompasses the prioritization, evaluation, and implementation of appropriate security controls identified during the risk assessment phase.
Risk Mitigation Strategies for Operations and Maintenance Activities
Final Report October 2011
Sponsored by Iowa Highway Research Board (IHRB Project TR-627) Iowa Department of Transportation Midwest Transportation Consortium (InTrans Project 10-389)
About CMAT
The mission of the Construction Management and Technology (CMAT) Program is to improve the effficiency and cost-effectiveness of planning, designing, constructing, and operating transportation facilities through innovative construction processes and technologies.
About MTC
The Midwest Transportation Consortium (MTC) is a Tier 1 University Transportation Center (UTC) that includes Iowa State University, the University of Iowa, and the University of Northern Iowa. The mission of the UTC program is to advance U.S. technology and expertise in the many disciplines comprising transportation through the mechanisms of education, research, and technology transfer at university-based centers of excellence. Iowa State University, through its Institute for Transportation (InTrans), is the MTC’s lead institution.
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Technical Report Documentation Page 1. Report No. IHRB Project TR-627 4. Title and Subtitle Risk Mitigation Strategies for Operations and Maintenance Activities 5. Report Date October 2011 6. Performing Organization Code 7. Author(s) Kelly C. Strong and Jennifer S. Shane 9. Performing Organization Name and Address Institute for Transportation Iowa State University 2711 South Loop Drive, Suite 4700 Ames, IA 50010-8664 12. Sponsoring Organization Name and Address Iowa Highway Research Board Midwest Transportation Consortium Iowa Department of Transportation Institute for Transportation 800 Lincoln Way 2711 South Loop Drive, Suite 4700 Ames, IA 50010 Ames, IA 50010-8664 15. Supplementary Notes Visit www.intrans.iastate.edu for a color pdf of this and other research reports. 16. Abstract The objective of this research was to investigate the application of integrated risk modeling to operations and maintenance activities, specifically moving operations, such as pavement testing, pavement marking, painting, snow removal, shoulder work, mowing, and so forth. The ultimate goal is to reduce the frequency and intensity of loss events (property damage, personal injury, and fatality) during operations and maintenance activities. 8. Performing Organization Report No. InTrans Project 10-389 10. Work Unit No. (TRAIS) 11. Contract or Grant No. 2. Government Accession No. 3. Recipient’s Catalog No.
13. Type of Report and Period Covered Final Report 14. Sponsoring Agency Code
17. Key Words highway maintenance activities—operations and maintenance—risk mitigation— roadwork risk modeling—traffic control—work-zone safety 19. Security Classification (of this report) Unclassified. Form DOT F 1700.7 (8-72) 20. Security Classification (of this page) Unclassified.
18. Distribution Statement No restrictions. 21. No. of Pages 108 22. Price NA Reproduction of completed page authorized
RISK MITIGATION STRATEGIES FOR OPERATIONS AND MAINTENANCE ACTIVITIES
Final Report October 2011 Principal Investigator Kelly C. Strong, Associate Professor Department of Civil, Construction, and Environmental Engineering Iowa State University Co-Principal Investigator Jennifer S. Shane, Assistant Professor Department of Civil, Construction, and Environmental Engineering Director of Construction Management and Technology (CMAT) Iowa State University Research Assistants Sayanti Mukhpadhay and Jay Mathes Authors Kelly C. Strong and Jennifer S. Shane Sponsored by the Iowa Highway Research Board (IHRB Project TR-627) and the Midwest Transportation Consortium Preparation of this report was financed in part through funds provided by the Iowa Department of Transportation through its research management agreement with the Institute for Transportation (InTrans Project 10-389) A report from Institute for Transportation Iowa State University 2711 South Loop Drive, Suite 4700 Ames, IA 50010-8664 Phone: 515-294-4015 Fax: 515-294-0467 www.intrans.iastate.edu
TABLE OF CONTENTS ACKNOWLEDGMENTS ............................................................................................................. ix EXECUTIVE SUMMARY ........................................................................................................... xi Problem Statement ............................................................................................................. xi Objective ............................................................................................................................ xi Research Description ......................................................................................................... xi Key Findings .................................................................................................................... xiii Research Limitations ....................................................................................................... xiv Implementation Readiness .................................................................................................xv Implementation Benefits ....................................................................................................xv INTRODUCTION ...........................................................................................................................1 Problem Statement ...............................................................................................................1 Objectives ............................................................................................................................1 LITERATURE REVIEW ................................................................................................................3 Weather/Environment ..........................................................................................................3 Mobile and Short-Duration Operations/Maintenance Activities and Equipment ................6 Literature Review Conclusions ..........................................................................................18 RESEARCH METHODOLOGY...................................................................................................19 Identification of Current O/M processes through Expert Input .........................................19 Literature Review...............................................................................................................19 Analysis of the Crash Data ................................................................................................20 Validation Survey ..............................................................................................................23 Identification of Mitigation Strategies ...............................................................................23 DATA ANALYSIS ........................................................................................................................24 Crash Database Analysis Results .......................................................................................24 Validation Survey Data Analysis Results ..........................................................................40 Development of the Integrated Risk Management Model .................................................59 DISCUSSION OF KEY FINDINGS .............................................................................................62 Crash Data Analysis ...........................................................................................................62 Validation Survey Data Analysis .......................................................................................64 Identification of Risk Mitigation Strategies .......................................................................66 Research Limitations .........................................................................................................67 Implementation Readiness .................................................................................................67 Implementation Benefits ....................................................................................................68 REFERENCES ..............................................................................................................................69 APPENDIX A. LIGHTING STUDIES .........................................................................................71 Study 1: Effect of Warning Lamps on Pedestrian Visibility and Driver Behavior ...........71 Study 2: Recommendations for Service Equipment Warning Lights ................................71 Study 3: LED Warning Lights for DOT Vehicles .............................................................72 v
APPENDIX B. EXPERT PANEL SUMMARY REPORTS .........................................................73 TAC Kick-Off Meeting......................................................................................................73 Current O/M Processes and Practices ................................................................................74 APPENDIX C. EXPERT INTERVIEWS......................................................................................83 Follow-Up Interview with Bob Younie, State Maintenance Engineer ..............................83 Interview with Mark Black, Iowa DOT District 2 Engineer .............................................86 Interview with Jeff Koudelka, Vice President of Iowa Plains Signing, Inc. .....................89
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LIST OF FIGURES Figure 1. The Balsi Beam being rotated from side to side.............................................................12 Figure 2. Dancing diamonds (lights) .............................................................................................13 Figure 3. Flagger stopping traffic (left) and portable temporary rumble strips being field tested near Perry, Kansas (right)................................................................................13 Figure 4. Cone shooter ...................................................................................................................14 Figure 5. Automated pavement crack sealer ..................................................................................15 Figure 6. Robotic safety barrel (RSB) ...........................................................................................15 Figure 7. Truck-mounted changeable message signs (event example, left, and lane-blocked example, right) ...................................................................................................................16 Figure 8. Percentage distribution of statewide work-zone crashes according to severity over 10 years (2001–2010) ........................................................................................................25 Figure 9. Statewide work-zone crash severity distribution—total crashes (2001–2010) ..............25 Figure 10. Distribution of the weighted average for the probabilities of the factors for the occurrence of the different types of crashes ......................................................................35 Figure 11. Distribution of the percentage frequency of the factors (crash database) present in all crashes involving intermittent and moving work zones and work on the shoulders and median .........................................................................................................38 Figure 12. Distribution of the severity levels of the factors (crash database) present in all crashes involving intermittent and moving work zones and work on the shoulders and median .........................................................................................................................50 Figure 13. Distribution of the percentage frequency of the factors (crash database) present in all crashes involving intermittent and moving work zones and work on the shoulders and median .........................................................................................................54 Figure 14. Risk assessment matrix.................................................................................................60 Figure C.1. December 2010 Iowa DOT Highway Division organizational chart .........................84 Figure C.2. December 2010 Iowa DOT District 2 Highway Division organizational chart .........85 Figure C.3. Sample traffic control diagram for a shoulder closure ...............................................88 Figure C.4. Truck-mounted traffic attenuator ................................................................................89 Figure C.5. Desired versus dangerous passing path ......................................................................90 Figure C.6. Temporary rumble strips .............................................................................................91
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LIST OF TABLES Table 1a. Effective technologies/safety devices for mobile operations ...........................................9 Table 1b. Effective technologies/safety devices for mobile operations ........................................10 Table 2. Techniques adopted for safer mobile work zones ...........................................................11 Table 3. Criteria satisfied by selected work-zone device/equipment ............................................11 Table 4. Variables queried from the Iowa crash database .............................................................20 Table 5. Iowa statewide work-zone crash statistics .......................................................................24 Table 6. Descriptive statistics and significance of the indicator variables created or used in the model ............................................................................................................................27 Table 7. Variable description and results .......................................................................................30 Table 8. Marginal effects of the factors along with their severities...............................................33 Table 9. Ranking of the factors according to severity ...................................................................36 Table 10. Frequency distribution of the factors .............................................................................37 Table 11. Ranking of significant factors according to their frequency of occurrence ...................39 Table 12. Risk values of the significant factors .............................................................................40 Table 13. Severity levels of the factor ...........................................................................................41 Table 14. Frequency distribution of the factors .............................................................................45 Table 15. Ranking of the factors according to severity .................................................................51 Table 16. Ranking of the factors according to frequency ..............................................................55 Table 17. Ranking of the factors according to risk assessment value ...........................................57
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ACKNOWLEDGMENTS The authors would like to thank the Iowa Highway Research Board (IHRB), the Iowa Department of Transportation (DOT), and the Midwest Transportation Consortium (MTC) for their financial support of this project, and the Institute of Transportation (InTrans) for administrative and publication support. In addition, the insights and guidance of the following individuals were extremely valuable: Bob Younie – Iowa DOT project liaison Technical Advisory Committee: ? ? ? ? ? ? ? ? Mark Black – Iowa DOT Highway Division District 2 Lynn Deaton – Iowa DOT Paint Crew District 1 Kevin Jones – Iowa DOT Materials Inspection Staff Robert Kieffer, Boone County Secondary Road Department Engineering Jeff Koudelka – Iowa Plains Signing, Inc. Dan Sprengeler – Iowa DOT Office of Traffic and Safety Brent Terry – Iowa DOT Materials Inspection Staff Tracy Warner – City of Ames Municipal Engineering
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EXECUTIVE SUMMARY Problem Statement Previous research on construction work-zone safety found that moving operations represent the highest-risk activity when considering both frequency of occurrence and crash severity (Shane et al. 2009). The research further determined that using an integrated risk model that assesses risk over the project life cycle could mitigate the risk of moving operations (among others) during the construction phase. Hence, this research examines how an integrated risk-modeling approach could be used to reduce the frequency and intensity of loss events (property damage, personal injury, fatality) during highway operations and maintenance (O/M) activities. Objective The objective of this research is to investigate the application of integrated risk modeling to O/M activities, specifically moving operations such as pavement and structures testing, pavement marking, painting, shoulder work, mowing, and so forth. Research Description The methodologies that were adopted in this research are as follows: ? ? ? ? ? Identification of current O/M processes through expert input Literature review Analysis of crash data Validation survey Identification of mitigation strategies
Identification of Current O/M processes through Expert Input The research started with an expert panel session/brainstorming workshop with the technical advisory committee (TAC) aimed at mapping the O/M process as currently utilized by state, county, and local agencies. The objective was to categorize the activities, environments, tools/equipment, and relationships involved with different O/M functions. This session was followed up by in-depth interviews with three members of the expert panel. Literature Review The researchers performed an extensive literature search compiled a preliminary list of risk factors and loss events during O/M activities. The search mainly included results from academic
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journals, trade publications, transportation research technical reports, and state departments of transportation (DOT) web sites. The literature review reveals several studies on the impacts of weather on the roadways and, hence, its effects on work-zone safety, along with specific research on the interaction of traffic and O/M and mobile work-zone-related safety. However, these studies did not specifically address risk assessment and mitigation strategies for the O/M activities on highways. The literature search also gave insight into how the identified factors play a role in mobile workzone crashes, specifically work zones that involve O/M activities on highways. Analysis of Crash Data The analysis of the crash database provided by the Iowa DOT played a very important role in the development of the Integrated Risk Management Model. To obtain information about the relevant crashes, a query was created to gather data for all severity level of crashes from 2001 through 2010 that involved two types of work zones: intermittent or moving work and work on shoulder or median. The suitable variables in the crash database that were able to explain the effect of the previouslyidentified factors (activities, environment, tools/equipment, and relationships) were queried to analyze their effect on crash severities and the frequency with which they occur within the database. The Integrated Risk Management Model consists of two parts: factors contributing to the severity of the crash and the frequency of the factors involved in the crashes. In this research study, the significance of the factors contributing to the severity of the crash was assessed by developing a statistical model and the frequency of those factors that were found to be significant in the model was assessed through descriptive statistics of the crash database. The researchers examined weather (environment), equipment, activities, and related factors to develop a risk severity matrix to indicate the relative severity of each factor on a Likert scale of 1 to 5. By performing an analysis of the crash database, the researchers generated a model (and refined it) to show the relationships between the various factors and the severity and frequency of crashes in mobile work zones. Validation Survey Data Analysis Results The loss events identified in the literature review and crash data analysis were validated in a short survey that was administered to state, county, and local O/M personnel, as well as to traffic safety professionals in the private sector, including both office and field personnel. The survey assisted the research team in ranking loss events in order of risk (frequency and severity). The survey questions included the O/M activities identified from the expert panel session. The participants were asked to rank those activities from their experience according to their severity
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and likelihood of occurrence (frequency), both of which were measured with a Likert scale rank value from 0 to 5. The number of responses obtained was 24. Because of the small sample size, no statistical tests were performed with the survey results. These results were used only to validate the results obtained through the statistical analysis of the crash database. Identification of Mitigation Strategies After identifying potential risk factors, establishing proximate causes, and estimating frequency and severity, the research team identified risk mitigation strategies that could be used to reduce the frequency and/or severity of losses during O/M activities. The potential mitigation strategies were identified after a meeting with the TAC members. Key Findings After identifying potential risk factors and evaluating loss severity, the research team identified the following risk mitigation strategies that can be used within integrated teams to reduce the frequency and/or severity of losses during O/M activities. 1. Revise and integrate the Iowa DOT Instructional Memorandums (IM), Traffic and Safety Manual, and Standard Road Plans – TC Series (traffic control diagrams) and related notes to provide clear guidance on placement of traffic control measures for mobile work zones. 2. Consider expanding traffic-control options to include proven technologies such as the Balsi Beam, portable rumble strips, blue strobe lights, and other innovations. Traffic-control specifications and associated allocation of risk between contractors and state/local agencies would also need to be revised to encourage adoption of new traffic-control measures. This is an area where a follow-up study would prove beneficial. 3. Investigate new delivery technologies (such as Skype, webinars, and remote conferencing) to allow for improved training within the flattened structure of the Iowa DOT. The training should include both formal programs for centralized functions and informal weekly programs for supervisory personnel to discuss issues with field crews. The Local Technical Assistance Program (LTAP) at the Institute for Transportation (InTrans) may be of assistance in developing such a safety-training program. The safety-training program will be particularly helpful for new and temporary employees working in mobile operations. 4. Written manuals and training programs should focus on the importance of worker and equipment visibility and advance warning systems, especially in high-speed environments (interstates and US highways) and those where drivers may be distracted more easily by pedestrians, traffic signals, bicyclists, etc., such as municipal streets.
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5. Schedule Best Practices meetings regularly within divisions. Encourage shop management to meet with division managers and other shop managers to discuss best practices that are discovered in the field, especially when it comes to safety. Division managers should also hold meetings periodically to encourage this type of information sharing. The alternative delivery technologies mentioned above may also be helpful in disseminating best practices. 6. Certain environments should be reviewed to ensure that the minimum number of workers and vehicles are used in the traffic-control system. Specifically, two lane two-way highways, work at railroads and other utility sites, overhead work, and work on bridges are likely highrisk environments where additional vehicles and workers increase the risk of crashes. The value of impact attenuators should be researched to determine the safety benefits of such equipment. The analysis of the crash database did not find any reports of impact attenuators associated with mobile work-zone crashes. 7. Policies and safety training programs should emphasize the need for locating traffic controls at the appropriate distance from the work site to allow for driver reactions, and traffic controls should be moved at the same pace as the mobile operations whenever possible. The research report includes a comprehensive discussion of findings beyond what’s included here. Research Limitations The limitations of this research study are as follows. ? Not all of the factors/hazards that were studied in this research could be described by the crash database variables queried. Representative variables were selected and analyzed from the crash database, which indirectly explained the effect of the required variables/factors/hazards. The data entered on the responding officer’s report does not always match the variable of interest. The crash data were drawn from the Iowa crash database, but the survey and literature review was national in scope. This made the research study somewhat biased. To get a good sample size, crash data from the last 10 years (2001 through 2010) were analyzed. This may have included information about several crashes that occurred after changes in work-zone signage practices and other infrastructure development. The response rate for the validation survey was low. Because of the sample size, no statistical analysis could be performed.
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Implementation Readiness The possible mitigation strategies developed as a result of this research are not field-tested, as it was out of the scope of this research project. If further research on the implementation ideas is needed, a separate research study can be conducted focusing on the implementation of the riskmitigation techniques found as a result of this study. Testing may include evaluation of the riskmitigation strategies in simulators or actual field situations to determine effectiveness. Implementation Benefits The research findings are intended to provide a process map or guidebook outline for use by the Iowa DOT, Iowa county engineers, and municipal transportation agencies to assess the risk potential of various O/M activities and develop team-based risk-mitigation strategies. The primary benefits of this research are the reduced risk of injury, fatality, and property damage for O/M and the traveling public. The research results can be implemented by the Iowa DOT staff, county engineers, municipal transportation directors, and any other transportation professionals responsible for O/M activities, including field personnel. The results can also be used as a standard process for identifying highest-risk O/M activities and developing mitigation strategies to reduce those risks. However, it should be noted that the riskmitigation processes developed and envisioned in this research are highly inclusive, involving state, local, and regional professionals from both field and office positions. Intuitively, any process that decreases risk should improve worker safety, lower agency costs, improve service to the traveling public, and lead to more-efficient procedures over the long-term, although these specific performance benefits are not assessed directly as part of this research project.
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INTRODUCTION Problem Statement Previous research on construction work-zone safety found that moving operations represent the highest risk activity when both frequency of occurrence and severity of loss are considered (Shane et al. 2009). The research further determined that using an integrated risk model that assesses risk over the project life cycle could mitigate the risk of moving operations (among others) during the construction phase. Although designed specifically to examine risk and safety for work-zone applications, the research indicated that construction activities that involve moving operations (e.g., painting, guardrail placement) represented the highest risk. This finding suggests that the risk-modeling process could be applied beneficially to operations and maintenance (O/M) functions outside of static construction work-zone applications. Hence, this research examines how an integrated risk-modeling approach could be used to reduce the frequency and intensity of loss events (property damage, personal injury, fatality) during highway O/M activities. Objectives The objective of this research is to investigate the application of integrated risk modeling to O/M activities, specifically moving operations such as pavement and structures testing, pavement marking, painting, shoulder work, mowing, and so forth. The ultimate goal is to reduce frequency and severity of loss events (property damage, personal injury, and fatality) during O/M activities. Potential risk factors to explore included the following issues: ? ? ? ? ? ? ? ? ? ? ? Traffic level/congestion Number of roadway lanes Posted speed limit Inadequate/improper signage Inadequate/improper vehicle lighting and marking Insufficient worker training Proximity of obstructions (equipment) to traveled roadway Physical limitations of crash attenuators Limitations of equipment due to the specialized nature of the fleet Weather (condition of road surface, visibility, etc.) Work under traffic (inadequate separation or lack of detours/lane shifts)
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After identifying potential risk factors and evaluating loss severity, the research team identified risk mitigation strategies that can be used within integrated teams to reduce the frequency and/or severity of losses during O/M activities.
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LITERATURE REVIEW The literature review is intended to identify the current and common practices for safe and efficient highway O/M that have been adopted by different state departments of transportation (DOTs) and other agencies throughout the world. The review also attempted to find out some of the factors that increase the likelihood of vehicle crashes during any type of mobile operations on highways, like testing, painting, repairing and replacement of guardrails, etc., and how the different agencies take precautionary measures to mitigate the chance of crashes due to these factors. However, it has been found that most of the research has been done on the impacts of weather and different climatic changes on highways and other surface transportation systems with only a few studies focusing on the identification of traffic control devices and safety for mobile and short-duration work zones. Much less focus has been given to a comprehensive examination of risk factors and mitigation strategies for mobile operations, which is the focus of this research project. Weather/Environment The National Research Council estimated that drivers endure more than 500 million hours of delay annually on the nation’s highways and principal arterial roads because of fog, snow, and ice, excluding delays due to rain and wet pavement (Qin et al. 2006). Furthermore, 1.5 million vehicular crashes each year, accounting for approximately 800,000 injuries and 7,000 fatalities, are related to adverse weather and the injuries, loss of lives, and property damage from weather related-crashes cost an average of 42 billion dollars in the US annually (Qin et al. 2006). Weather and climate changes have a great impact on surface transportation safety and operations. In the future, with the increase in global warming, transportation managers would need to modify the advisory, control, and treatment strategies to an appropriate level and implement several modern risk mitigation strategies to limit the weather impacts on roadway safety and operations (Pisano et al. 2002). Moreover, weather also acts through visibility impairments, precipitation, high winds, temperature extremes, and lightning to affect driver capabilities, vehicle maneuverability, pavement friction, and roadway infrastructure. According to the National Center for Statistics and Analysis in 2001, the combination of adverse weather and poor pavement conditions contributes to 18 percent of fatal crashes and 22 percent of injury crashes annually (Pisano et al. 2002). The crash risk increases during the rainfall, especially if rain is followed after a period of dry weather. In fact, the crash risk during rainfall was found to be 70 percent higher than the crash risk under clear and dry conditions (Pisano et al. 2008). In winter, however, the drivers adjust their behaviors sufficiently to reduce the crash severity during snowfall but not enough to lower the crash frequency.
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The traffic volumes during snow events were also found to be 30 percent lower than volumes in clear weather signifying that the drivers themselves become cautious and reluctant to travel during a snow event (Pisano et al. 2008). Furthermore, on analysis of the 10 years of winter crash data on Iowa interstates, the crash risk was found to be 3.5 times higher at the start of the winter than it was at the end. Another interesting result propounded by Pisano et al. (2008) was wet weather being much more dangerous when compared to winter weather in terms of both crash frequency and severity. The combination of high traffic volumes, relatively high speeds, and low traction likely explains why most of the weather-related crashes occur during rainfall and on wet pavement. In fact, 47 percent of weather-related crashes happen in the rain and the annual cost of these crashes are estimated nationally between $22 billion (for only those crashes that are reported) and $51 billion (for both the reported and unreported crashes, because about 57 percent of the crashes are not reported to police, according to the National Highway Traffic Safety Administration/NHTSA report by Blincoe et al. (2002)) (Pisano et al. 2008). The different strategies recommended in the research to mitigate these kinds of weather-related risks are advisory (announcing the road weather information prior to the actual event so motorists can take precautionary measures), control (access control, speed management, and weather-related signal timing are the three different types of control that increase road safety), and treatment strategy (includes fixed and mobile anti-icing/deicing systems, chemical sequences, etc.). Several road-weather-management research programs targeted toward traffic, emergency, and winter maintenance management would help to increase the safety, mobility, and productivity of the nation’s roadways and would also benefit national security and environmental quality (Pisano et al. 2008). Research by Goodwin (2003) on best practices for road weather management contained 30 case studies of systems in 21 states that improve the roadway operations under inclement weather conditions including fog, high winds, snow, rain, ice, flooding, tornadoes, hurricanes, and avalanches. This research also mentioned three types of mitigation strategies in response to the control threats: advisory (provide information on prevailing and predicted conditions to both transportation managers and motorists), control (restrict traffic flow and regulate roadway capacity), and treatment strategies (apply resources to roadways to minimize or eliminate weather impacts). The Alabama DOT (ALDOT) developed and installed a low-visibility warning system integrated with a tunnel management system to reduce the impact of low visibility due to fog. The California DOT (Caltrans) developed a motorist warning system for use during low visibility caused by windblown dust in summer and dense localized fog in the winter. Goodwin (2003) reports that in Aurora, Colorado, a maintenance-vehicle management system (MVMS) was implemented to monitor the operation of maintenance vehicles including snowplows and street sweepers. Vehicles were outfitted with MVMS equipment and a global 4
positioning system (GPS), which tracked the location of the vehicles. This information was controlled centrally, allowing for the transmission of pre-programmed, customized messages to a single vehicle, a selected group of vehicles, or to all vehicles. The MVMS could also monitor road treatment activities. With the MVMS monitoring system, transportation managers could easily provide information to citizens about operations and maintenance activities on a particular street or roadway. In addition, treatment costs were minimized and productivity increased 12 percent. Qin et al. (2006) conducted research to investigate the impact of snowstorms on traffic safety in Wisconsin. The temporal distribution of crash occurrences showed that a large percentage of the crashes occurred during the initial stages of the snowstorms, indicating that to be the most risky time of travel on the highways during a snowstorm. The factors responsible for the risks were low friction pavement, which makes operating and maneuvering vehicles difficult, impaired visibility due to blowing snow or fog, which limits drivers’ sight distance, accumulating or drifting snow on the roadway, which covers pavement markings and obstructs vehicles, drivers’ inadequate perception and comprehension of the snowstorm event, and high traffic volumes. The researchers also found that the highest risk of crashes occurred at traffic flow rates from 1,200 to 1,500 vehicles per hour per lane under snow conditions. In the same study, the researchers also found that higher wind speeds/gusts pose high risks causing more severe crashes than higher snowfall intensity. The mitigation strategies suggested by the researchers to render a “passable roadway” (roadway surface free from drifts, snow ridges, ice, and snowpack and can be traveled safely at reasonable speeds without losing traction by the vehicles) were proper winter maintenance operations such as snow plowing and de-icing techniques, like salting and sanding. In the US, the crash frequency was eight times higher on a two-lane highway and 4.5 times higher on a multilane freeway before the deicing techniques were applied than that after the application; the crash frequency was nine times and seven times higher on two-lane highways and multi-lane freeways, respectively, before the application of salt than that after the application, with a crash severity reduction of 30 percent (Qin et al. 2006). The outcomes of this research were as follows: (1) snow plowing and spreader trucks should be sent out prior to the start of the storm event to reduce the number of crashes, (2) the winter maintenance crews should be deployed earlier to significantly reduce crash occurrence, (3) severity of snowstorm and snowfall will increase crash occurrence, and (4) higher wind speed causes more severe crashes (Qin et al. 2006). An interesting result from this study was that freezing rain does not cause more crashes than non-freezing rain, which is counter intuitive given the notoriety of the “black ice” phenomenon pavements. Research by Shi (2010) recommended several best practices for winter road-maintenance activities, including the use of a software tool for computer-aided design of passive snow control
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measures to reduce maintenance costs and closure times, use of anti-icing and pre-wetting techniques, and use of improved weather forecasts through several modern technologies: 1. Road Weather Information Systems/Environmental Sensor Stations (RWIS-ESS), which is an aggregation of roadside sensing and processing equipment used to measure the current weather conditions and road environment such as pavement temperature and pavement conditions in addition to atmospheric conditions and thus aid in winter maintenance decisions 2. Mesonets, which are used as regional networks of weather information integrating the observational data from a variety of sources and thus provide a more comprehensive and accurate picture of the current weather conditions and great potential for improved weather forecasts 3. Fixed Automated Spray Technology (FAST) that is used for anti-icing at key locations enabling the winter maintenance personnel to treat potential conditions before snow and ice problems arise; coupled with RWIS and other reliable weather forecasts, the technology promotes the paradigm shift from being reactive to proactive in fighting winter storms 4. Advanced snowplow technologies, such as automatic vehicle location (AVL), which are vehicle-based sensors, surface-temperature measuring devices, freezing point and ice presence detection sensors, salinity measuring devices, visual and multispectral sensors, and millimeter wavelength radar sensors that have immense importance in winter road-maintenance procedures 5. Maintenance Decision Support Systems (MDSS), which are computer-based systems that integrate current weather observations and forecasts to support maintenance agency response to winter weather events and provides real-time road treatment guidance for each maintenance route Mobile and Short-Duration Operations/Maintenance Activities and Equipment As the highway system reaches the end of its serviceable life, it becomes necessary for transportation agencies to focus on the preservation, rehabilitation, and maintenance of these roads. With significant increase in the number of work-zone activities, transportation officials and contractors are challenged with finding ways to reduce the impact of maintenance activities on driver mobility. In addition, agency leaders are sorting out ways to mitigate risks posed by obstructions to vehicles in work zones. A study by Sorenson et al. (1998) on maintaining customer-driven highways focused on the efforts by the Federal Highway Administration (FHWA) to minimize traffic backups and travel delays caused by highway maintenance, rehabilitation, and reconstruction. The study also investigated traffic management practices and policies intended to cut down on work-zone
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congestion and minimize crash risks. Finally, the study identified contracting and maintenance procedures to cut the time from start to finish in pavement rehabilitation projects. Through extensive interviews with 26 state highway agencies, the research formulated the best traffic management practices and policies that most of the states use to cut down on work-zone congestion and to minimize crash risks for drivers and highway workers. Specific examples of state DOT practices identified in the study are discussed as follows: 1. The Oregon DOT (ODOT) used an innovative contracting technique, awarding contracts based not on the lowest bid, but on a combination of price and qualifications. The innovative contracting introduced a system of awarding incentives if the work is done earlier or a penalty if it is delayed. The use of “lane rental” charged a rental fee to the contractor based on the road user costs for those periods of time when the traffic is obstructed through the lane or shoulder closures. 2. The New Jersey DOT (NJDOT) recommended performing work at night and providing the public with shuttle buses and other transportation alternatives during the construction/rehabilitation of the highways to mitigate the negative impact of the project on the traffic flow. They also assigned a state patrol unit full time to state DOT construction projects to assist with traffic control and increase work-zone safety. 3. The North Carolina DOT (NCDOT) initiated a public information program that informs motorists, businesses, and residents of upcoming road construction and encourages them to use alternate routes. The researchers also interviewed the road users regarding optimizing highway performance and the findings were noteworthy. For example, in addition to reducing traffic congestion caused by work zones, the public demanded the following things: ? ? ? ? ? ? ? Increased public awareness of the highway construction process Longer lasting pavements Non-traditional work schedules such as evening and weekend road closures Upgraded product performance Improved communications with the public—with the help of portable traffic management systems consisting of video detection cameras and a series of variable message signs Educating drivers about how to navigate safely through work zones by using videotapes and other media to describe the construction and rehabilitation process High-performance hot-mix asphalt (HMA) to increase the lifetime of the highways and thus minimize disruptions caused by construction and maintenance work
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Moriarty et al. (2008) examined the impact of preservation, rehabilitation and maintenance activities on traffic. The researchers developed several simulation models to estimate delays, queues, and delay-related costs associated with traffic impacts created by work zones. The simulation results provided a low-risk, low-cost environment and helped in improving the planning and design of work zones; however, these simulation results only provided guidance to the users who must have a fundamental understanding of the highway capacity analyses and traffic flow fundamentals. A study by Paaswell et al. (2006) on traffic control devices for mobile and short-duration operations was conducted to focus on the following: ? ? ? Identification of state-of-the-art work-zone safety technologies to improve worker safety in the mobile work zones Methods for improving the information systems for work-zone traffic control to reduce delays and crashes Introduction of best practices for the use of law enforcement to improve workzone safety along with identifying the key issues to be considered from public outreach and information systems
The study was done in New Jersey for NJDOT and the team found that most of the NJDOT mobile and short-duration work-zone crashes were caused by careless driving, speeding, and motorist inattention. Hence, safety devices should be selected based on their ability to reduce traffic speed through work zones, improve motorists’ recognition of work-zone hazards, and improve motorists’ attention to signs in the work zone. The researchers also noted the Texas DOT (TxDOT) had found operational problems with mobile work-zone configurations that included the improper use of arrow-boards, the lack of uniform procedures for freeway entry and exit, large spacing between caravan vehicles, and unnecessary lane blockage by the caravan. Also included in the report, Caltrans conducted the Caltrans Worker Safety Program, which included construction and maintenance-worker safety orientation and a District Driver Training Program to eliminate employee preventable vehicle accidents (Paaswell et al. 2006). The FHWA recommended the use of automated enforcement and intrusions alarms as well as uniformed police officers to improve traffic safety at highway work zones. Motorists’ information about the work zones, education and outreach systems, and proper training of the workers were mentioned as important factors responsible for decreasing the risks of crashes in mobile work zones. The review of work operations found that safety for mobile operations of pothole patching, sweeping, spraying and mobile patching was in accordance with Manual on Uniform Traffic Control Devices (MUTCD) requirements, but workers requested improved devices such as strobe lights and improved reflective materials for signs to get drivers’ attention (Paaswell et al.
8
(includes flip disk, lightemitting diode, fiber-optic, etc.)
(series of synchronous flashing lights)
FHWA Research Program X X Advanced warning signs X X Flashing lights Dancing diamonds (lights) X Rotating lights/strobe lights X Flashing Stop/Slow paddle All-terrain sign and stand X X Drone radar/speed indicator X Radar-triggered speed displays X Dynamic message signs X Direction indicator barricade X Lighted raised pavement markers X Robotic highway safety markers Variable message signs (VMS) X X Fluorescent/bright lights (yellow/green gives best visibility)
New York State DOT Strategic Highway Research Program
Institution or Agency
New Jersey DOT
Kansas DOT
Special Lights/Signs/Indicators/Markers
Table 1a. Effective technologies/safety devices for mobile operations
2006). The Paaswell study is very thorough and helps provide several informative findings, which are summarized in Tables 1a, 1b, 2, and 3.
9
(attracts drivers’ attention)
X
X
Missouri DOT
FHWA Research Program X Reflectorized/bright suits and vests Remotely-operated auto flagger Truck-mounted attenuators and message boards CB Wizard alert system Rumble strips Lane merger system White lane drop box Shadow vehicles Barrier vehicles Advance warning vehicles Cone shooter X Automated pavement crack sealers Automated debris removal vehicle X Balsi Beam Automated enforcement and intrusion alarms X Vehicle intrusion alarms (both audio and visual) X Salt spreader truck-mounted attenuator (TMA) X Queue detector X Special Instruments/Technologies X X X X X X orange X portable X X X X X X
Strategic Highway Research Program
Kansas DOT California DOT (Caltrans) New York State DOT
Institution or Agency
New Jersey DOT
Table 1b. Effective technologies/safety devices for mobile operations
10
X X X longitudinal and random crack sealers X X X X X
Table 2. Techniques adopted for safer mobile work zones
Reduced Speed Limits Education and Outreach Systems for Training of Workers Uniformed Police Enforcement in Work Zone Reduced Channelization Spacing
Institution or Agency New York State DOT FHWA Research Program
X X
X
Enhanced Flagger Stations
X
X X
Table 3. Criteria satisfied by selected work-zone device/equipment
Work Zone Device Truck-mounted attenuator Vehicle intrusion alarm Rumble strips All-terrain sign and stand Directional indicator barricade Flashing Stop/Slow paddle Opposing traffic lane divider Queue detector Remotely-driven vehicle Portable crash cushion Cone shooter Pavement sealers Debris removal vehicle Balsi Beam Robotic highway safety marker Does not satisfy Partly satisfy Criteria: 1. Reduce exposure to the motorists/crew 2. Warn motorists/crew to minimize the likelihood of crash 3. Minimize severity of crashes once they occur 4. Provide separation between work crew and traffic 5. Improve work zone and traffic control device visibility Fully satisfy 1 2 Criteria 3 4 5
11
The evaluation criteria for device functionality in mobile operations would provide assistance in selecting appropriate traffic control devices for worker safety and the safe and efficient movement of traffic through mobile and short-duration work zones, as shown in Table 3, based on the utility and effectiveness of the devices mentioned in the study. Selected innovative technologies discussed by Paaswell et al. (2006), which show promise for operations and maintenance activities, are discussed in more detail below. Balsi Beam Developed by Caltrans, the Balsi Beam has great potential for protecting exposed workers in short-duration work operations (See Figure 1).
Figure 1. The Balsi Beam being rotated from side to side The beam provides positive protection from errant vehicles and is crashworthy as tested by National Cooperative Highway Research Program (NCHRP) criteria. Unlike portable concrete median barriers, which are labor/equipment intensive to set up and require a 42 in. clear zone between the barrier and the worker, the Balsi Beam can be set up in less than 10 minutes and requires no clear zone between the beam and workers. Caltrans is presently implementing the barrier for specialized concrete construction and bridge repair operations on high-speed interstate highways. The beam can be used in maintenance operations wherever workers are exposed to traffic in a limited area for several hours. Caltrans uses the beam for median barrier repairs, bridge deck patching and repairs, slab replacement and joint repairs, installation of bridge sealers, and guide rail and parapet repairs. The beam is used in conjunction with other safety equipment, such as truck-mounted attenuators, trucks, signs, and safety set up.
12
Dancing Diamonds (light panels) These signs (Figure 2) use a dancing-diamond panel, which is a matrix of light elements capable of either flashing and/or sequential displays and act as an advance caution device.
Figure 2. Dancing diamonds (lights) Rotating Lights/Strobe Lights Rotating/strobe lights were effective in getting drivers’ attention but not as useful in providing speed and closure rate information, especially when the service vehicle has stopped. Portable Rumble Strips Portable rumble strips (Figure 3) are placed temporarily on the road surface at a distance of about 100 meters (250 ft) in advance of the work zone and cause a vibration in the steering wheel and a rumble as vehicles pass over them, alerting drivers of changing conditions ahead and are best suited for low-speed roads that carry few heavy trucks.
Figure 3. Flagger stopping traffic (left) and portable temporary rumble strips being field tested near Perry, Kansas (right)
13
Portable rumble strips are very easy to use as the device weighs only 34 kg (75 lbs) and one or two workers can deploy them from the back of a pick-up truck. Cone Shooter A cone shooter (Figure 4) is a machine that can automatically place and retrieve traffic cones and, thus, open and close busy lanes safely and quickly without exposing workers to traffic.
Figure 4. Cone shooter (photo Copyright © AHMCT Research Center - UC Davis, 2010) Typical lane configurations use 80 traffic cones for each 1.5 miles of lane closure and the cones generally come in the 36 in. size. Manually, only three cones can be carried by a worker at a time, so the cone shooter helps in reducing both the cost and injury involved in a mobile work zone in a busy lane. Automated Pavement Crack Sealers Given that one of the most frequent maintenance operations involves pavement crack sealing and it is done by mobile operations, the Advanced Highway Maintenance and Construction Technology (AHMCT) Research Center has developed two automated crack sealers (Figure 5).
14
Figure 5. Automated pavement crack sealer The longitudinal and random crack sealers perform the operation with greater efficiency and in less time. Robotic Highway Safety Markers The Mechanical Engineering Department at the University of Nebraska-Lincoln has developed a mobile safety barrel robot (Figure 6) for efficient use in mobile work zones.
Figure 6. Robotic safety barrel (RSB)
15
The Robotic Safety Barrel (RSB) replaces the heavy base of a typical safety barrel with a mobile robot. The mobile robot can transport the safety barrel and robots can work in teams to provide traffic control. The robotic highway safety markers have been tested in field environments. Each robot moves individually. A single lead robot (the “General”) provides global planning and control and issues commands to each barrel (the “troops”). All robots operate as a team to close the right lane of a highway. The robotic safety barrels can self-deploy and self-retrieve, removing workers from exposure to moving traffic. The robots move independently so that they can be deployed in parallel and can reconfigure quickly as the work zone changes. These devices would be of great advantage in the mobile work zone where the cones or barrels could be programmed to move along with the working crew, saving time and increasing safety to workers. CB Wizard Alert System and Program CB Wizard is a portable radio that broadcasts real-time work-zone information and safety tips through radio channels. The advanced warning gives drivers the opportunity to moderate their speed and become observant of the need to slow, stop, or maneuver before they reach the work zone or encounter queues of halted vehicles. Truck-Mounted Changeable Message Signs Research at Texas A&M University has identified truck-mounted changeable message signs (TMCMS) (Figure 7) as an innovative technology that improves safety for both drivers and workers (Sun et al. 2011).
Figure 7. Truck-mounted changeable message signs (event example, left, and lane-blocked example, right) (photos Texas A&M University-Kingsville) 16
TMCMS can provide information to drivers in both symbols and text, and the truck-mounted deployment allows the information to be delivered to the driver at the closest possible point to the actual work site. Driver Behavior and Impacts on Truck-Mounted Attenuators Research by Steele and Vavrik (2010) explored driver behavior and identified some specific challenges that pose a risk for mobile work zones and lane closures such as providing adequate advance warning to motorists, decreasing driver speeds and heightening motorist awareness approaching the work zone, getting drivers to change lanes at a safe distance upstream of the work zone, and maintaining traffic in the open lane until a safe distance beyond the work space. The researchers observed that the return distance of the vehicles in the closed lane on urban expressways (high- and low-traffic during daytime) was as early as 25 ft in congested and 50 ft under free-flowing traffic, while the rural interstate traffic was more relaxed, returning to the closed lane 100 ft beyond the lead traffic control truck. However, in all cases, traffic came back into the closed lane at distances where workers would normally be present. It was also observed that increasing the visibility of the work crew by placing a lead truck downstream is an effective means of extending the buffer space at least by 200 ft and deterring drivers from returning to the closed lane too soon. Observation was also made about the workspace length. The analysis of predicted roll-ahead distances for truck-mounted attenuators (TMAs) impacted by vehicles of different sizes and speeds showed that for typical highway speeds, single- and multiple-unit trucks were capable of pushing the TMA into the work space creating a dual threat of lateral intrusions. So, the impacts on TMAs must be considered when developing traffic control standards. An important conclusion was made regarding nighttime mobile lane closure, which created hazardous conditions due to increased traffic speeds, decreased visibility, and increased numbers of impaired drivers. However, the addition of a flashing vehicle on the shoulder of the closed lane and 500 ft upstream reduced the number of vehicles approaching the work zone closely from 18.1 to 3.6 percent. Lighting Effective lighting is very important for service and maintenance vehicles. Although this is not included in the scope of this research work, a summary of three major studies regarding warning lights for service vehicles is provided in Appendix A.
17
Literature Review Conclusions The literature review reveals several studies on the impacts of weather on the roadways and, hence, its effects on work-zone safety, along with specific research on the interaction of traffic and O/M and mobile work-zone-related safety. However, these studies did not specifically address risk assessment and mitigation strategies for the O/M activities on highways. This research study examines weather (environment), equipment, activities, and related factors to develop a risk severity matrix to indicate the relative severity of each factor on a Likert scale of 1 to 5. An analysis of the crash database is also performed to generate a model showing the relationships between the various factors and the severity and frequency of crashes in mobile work zones.
18
RESEARCH METHODOLOGY The purpose of this section is to describe the research methods used to develop the Integrated Risk Management Model and identify, assess, and respond to the risks associated with highway O/M activities, such as pavement testing, pavement marking, painting, shoulder work, mowing, and so forth. As mentioned earlier, the ultimate goal of this research is to reduce the frequency and severity of loss events (property damage, personal injuries, and fatalities) during O/M activities. After potential risk factors were identified and loss frequency and severity had been evaluated, the research team identified risk mitigation strategies that can be used within integrated teams to reduce the frequency and/or severity of losses during O/M activities. The methodologies that were adopted in this research are as follows: ? ? ? ? ? Identification of current O/M processes through expert input Literature review Analysis of the crash data Validation survey Identification of mitigation strategies
Identification of Current O/M processes through Expert Input The research started with an expert panel session aimed at mapping the O/M process as currently utilized by state, county, and local agencies. The objective was to categorize the activities, environments, tools/equipment, and relationships involved with different operations and maintenance functions. The outcomes of the expert panel (technical advisory committee or TAC) session are described in Appendix B. Appendix C contains in-depth follow-up interviews with three members of the expert panel (Bob Younie, Mark Black, and Jeff Koudelka). Literature Review An extensive literature search was performed and a preliminary list of risk factors and loss events during O/M activities was identified. The search mainly included results from academic journals, trade publications, transportation research technical reports, and state DOT web sites. The primary websites used to facilitate the search for relevant publications were Google Scholar, the Transportation Research Board (TRB), Parks Library at Iowa State University, and the Iowa DOT Library. The literature search also gave insight into how the identified factors play a role in mobile work-zone crashes, specifically work zones that involve O/M activities on highways.
19
Analysis of the Crash Data The analysis of the crash database provided by the Iowa DOT played a very important role in the development of the Integrated Risk Management Model. To obtain information about the relevant crashes, a query was created to gather data for all severity level of crashes from 2001 through 2010 that involved two types of work zones (given we were focused on moving operations and not static work): intermittent or moving work and work on shoulder or median. The suitable variables in the crash database that were able to explain the effect of the previouslyidentified factors (activities, environment, tools/equipment, and relationships) were queried to analyze their effect on crash severities and the frequency with which they occur within the database. Table 4 shows the variables selected from the crash database to analyze the risk posed by each of the factors in O/M activities. Table 4. Variables queried from the Iowa crash database
Data Field (crash data) and Field Description Crash Severity CSEVERITY: Crash severities as measured Categories Fatal Major Injury Minor Injury Possible or Unknown Injury Property Damage Only (PDO) 1. 2. Work on shoulder or median Intermittent or moving work
Activity WZ_Type: Type of work activities involved Equipment FIRSTHARM: What the first harmful event is collision with SEQEVENTS1: In the sequence of events, what the first event is collision with EmerVeh: Emergency vehicle type EmerStatus: Emergency status of the vehicle considered VCONFIG: Vehicles involved in the crash
Impact Attenuator (fixed object) Impact Attenuator (fixed object)
Maintenance Vehicle 1. In emergency 2. Not in emergency 1. 2. 3. 4. 5. 6. 7. Passenger car Four-tire light truck Van or mini-van Motor home /recreational vehicle Motorcycle and sport utility vehicle Mopeds/Motorcycle Trucks and tractors (Single-unit truck two-axle, Single-unit truck ? three axles, Truck/trailer, Truck tractor, Tractor/semitrailer, Tractor/doubles, Tractor/triples and other heavy trucks) Bus (School bus > 15 seats, Small school bus nine to 15 seats, Other bus > 15 seats, and Other small bus nine to 15 seats) Maintenance or construction vehicle
8. 9.
20
Data Field (crash data) and Field Description Environment LIGHTING: Derived light conditions
Categories 1. Daylight 2. Darkness 3. Morning Twilight 4. Evening Twilight 1. Moving vehicles 2. Frosted windows/windshield 3. Blowing snow 4. Fog/smoke/dust Work-zone signs Mainline or ramp 1. Interstate 2. US Route 3. Iowa Route 4. Secondary Route 5. Municipal Route 6. Institutional Road 1. Work zone (construction/maintenance/utility) 2. Traffic control device inoperative/missing/obscured 1. 2. 3. 4. 5. 6. 1. 2. 3. 4. 5. 6. Cloudy Fog, smoke Rain Sleet, hail, freezing rain Snow Blowing sand, soil, dirt, snow Before work-zone warning sign Between advance warning sign and work area Within transition area for lane shift Within or adjacent to work activity Between end of work area and End Work Zone sign Other Driver ?18 years Driver > 18 and 15 seats, and Other small bus with nine to 15 seats) Vehicle configuration involved in crash is a maintenance/construction vehicle Daylight crash Crash when no daylight, i.e., during Darkness, Morning Twilight, or Evening Twilight Vision not obscured by anything Vision obstructed by frosted windows or windshield Vision obstructed by moving vehicle 0.0004 0.0001 0.0068 0.0016 0.0052 0.54293085 0.139875 0.10264889 0.11316813 0.0772 Variable Description Frequency Significance Indicator
BUS
0.0049
VCNFIGCO Environment DAYLIT NODAYLIT VNOBSCUR VOFROSTW VOMOVVEH
0.0077
0.8821 0.1180 0.9164 0.0002 0.0116
27
Variables VOWEATHE NOTFCONT TRAFCONW LOCRAMP LOCMAIN INTERSTA USROUTE IOWAROUT SECROAD MUNIROAD INSTROAD RCNTCIRC
Variable Description Vision obstructed by weather like blowing snow, fog, smoke, or dust No traffic control present near the work zone where the crash occurs Traffic control present near the crash work zone involves work-zone sign Crash location is near the ramp Crash location near the mainline Interstate route US route Iowa route Secondary road Municipal road Institutional road Contributing circumstances of the crash involves work-zone (construction/ maintenance/utility) Contributing circumstances of the crash involves inoperative/obscured/missing traffic control device Weather condition has blowing snow Weather condition is cloudy Weather condition is foggy or smoky Weather condition has rain Weather condition has snow Crash location is between the advance warning sign and work area Crash location is within or adjacent to the work activity Driver ? 18 years Driver > 18 and < 25 years 28
Frequency 0.0068 0.7293 0.0912 0.0545 0.9455 0.6305 0.1306 0.068 0.0545 0.1137 0.0009 0.9509
Significance Indicator
CNTNCRCTC
0.0006
BLOWSNOW CLOUDY FOGSMOKE RAIN SNOW BETAWWRK WTHWRKZN
0.0027 0.1129 0.0026 0.1633 0.0024 0.1663 0.6921
Driver Characteristics UNDDRI YONDRI 0.0594 0.2244
Variables MDDRI OLDRI VOLDRI IOWALCNC X16 OFSMLDR OFSFMDR
Variable Description Driver ? 25 and < 45 years Driver ? 45 and < 65 years Driver ? 65 years Iowa driver’s license Driver gender (male = 1, female = 0) Out-of-state male driver Out-of-state female driver
Frequency 0.3499 0.3304 0.0641 0.7904 0.5124 0.1587 0.1002
Significance Indicator
The final model of the crash severities was selected after a reiterative selection of the different independent variables through the LIMDEP software, which are shown in Table 7 with their beta coefficient and statistical significance.
29
Table 7. Variable description and results ID 1 2 Indicator/Variable Description Constant Crash Location Indicator 1 ( 1 if the crash location is between the advance warning sign and work area; 0 if otherwise) Crash Location Indicator 2 (1 if the crash location is within or adjacent to the work activity; 0 if otherwise) Crash Location Indicator 3 (1 if the location of the crash is near the ramp; 0 if otherwise) Cloudy Weather Indicator ( 1 if the weather condition is cloudy; 0 if otherwise) Under-Aged Driver Indicator (1 if driver ? 18 years; 0 if otherwise) Young-Aged Driver Indicator (1 if driver > 18 and < 25 years; 0 if otherwise) Middle-Aged Driver Indicator ( 1 if driver ? 25 and < 45 years; 0 if otherwise) Old-Aged Driver Indicator (1 if driver ? 45 and < 65 years; 0 if otherwise) Very Old-Aged Driver Indicator (1 if driver ? 65 years; 0 if otherwise) Time of Day Crash Indicator (1 if no daylight, i.e., either in darkness, morning twilight, or evening twilight; 0 if otherwise) Out-of-State Male Driver Indicator (1 if out-of-state male driver; 0 if otherwise) Out-of-State Female Driver Indicator (1 if out-of-state female driver; 0 if otherwise) Rain Indicator (1 if rain; 0 if otherwise) Interstate Route Indicator (1 if Interstate; 0 if otherwise) Variable Mnemonic Constant BETAWWRK Estimated Coefficient
-1.984366***
T-Statistic
-15.004 45.373
.91979447***
3
WTHWRKZN
.340550***
19.633
4
LOCRAMP
.107263***
4.445
5
CLOUDY
.8491091***
49.481
6 7
UNDDRI YONDRI
-.419101*** -.507994***
-9.814
-12.772
8
MDDRI
-.2448169***
-6.439
9
OLDRI
-.2721166***
-7.067
10 11
VOLDRI NODAYLIT
.1761806***
8.132
28.701
.4889586***
12
OFSMLDR
.1177997***
6.898
13
OFSFMDR
-.235061***
-9.695
14 15
RAIN INTERSTA
-.292615*** .551989***
-15.717 4.393
30
ID 16
Overall fit by ? - Square
Indicator/Variable Description US Route Indicator (1 if US Route; 0 if otherwise) 17 Secondary Road Indicator (1 if Secondary Route; 0 if otherwise) 18 Municipal Route Indicator (1 if Municipal Route; 0 if otherwise) 19 Iowa Route Indicator (1 if Iowa Route; 0 if otherwise) 20 Traffic Control Sign Indicator (1 if traffic control present near the crash work zone involves work-zone sign; 0 if otherwise) 21 Passenger Vehicle Indicator (1 if Passenger vehicle; 0 if otherwise) 22 Pick-up Truck Indicator (1 if fourtire light truck/pick-up truck; 0 if otherwise) 23 Van Indicator (1 if Van or Minivan; 0 if otherwise) 24 Truck and Tractor Indicator (1 if Single-unit truck two-axle, Singleunit truck ? three axles, Truck/trailer, Truck tractor, Tractor/semi-trailer, Tractor/doubles, Tractor/triples and other heavy trucks; 0 if otherwise) 25 Vision Not Obscured Indicator (1 if vision not obscured by any of the hindrances like moving vehicles, weather, etc., during the crash; 0 if otherwise) 26 Gender Indicator (1 if male driver; 0 if female driver) Threshold Parameter 27 ?1 28 ?2 NO. OF OBSERVATIONS Log likelihood function [LL(?)]
Variable Mnemonic USROUTE SECROAD MUNIROAD IOWAROUT TRAFCONW
Estimated Coefficient
1.191032*** 1.43160*** 1.112705*** 1.18880*** .02326043*
T-Statistic
9.434 11.252 8.800 9.367 1.28
PSVEH PCKTRK
.432212*** .353129***
25.049 16.581
VAN TRCKTRAC
.437940*** .535388***
19.581 21.932
VNOBSCUR
.328564***
14.660
X16
-.035858***
-3.008
.7617741*** 1.915051*** 55042 -49179.94
125.083 158.255
Restricted log likelihood [LL(C)] -54910.88 ? - Square = 1-LL(?)/LL(C) 0.104368023 adjusted ? - Square = 1-(LL(?)-k) 0.103858106 /LL(C)
31
k= number of parameters in the model K (No. of parameters in the unrestricted – No. of parameters in the restricted model] -2 [LL(?c) – LL(?)] X2critical [25 d.f.] Given that -2 [LL(?c) – LL(?)] > X2critical at significant at 99.99%. Overall fit by X2 estimate
28 28-3=25
11461.88 60.1403 ?=0.0001, we can state that the entire model is
***, **, * = Significance at 1%, 5%, 10% level, respectively For detailed statistical analysis, refer to Sayanti (2011) master’s thesis upon publication/distribution of it
The marginal effects for each response category are interpreted as a change in the outcome probability of each threshold category P(y=j) given a unit change in a continuous variable x (Washington et al. 2010). These values are dimensionless and relative and also do not carry any specific meaning. There are in fact two ways of estimating how much the event probability changes when a given predictor is changed by one unit. The marginal effect of a predictor is defined as the partial derivative of the event probability with respect to the predictor of interest. A more direct measure is the change in predicted probability for a unit change in the predictor. Being a derivative, the marginal effect is the slope of the line that is drawn tangent to the fitted probability curve at the selected point. Note that the marginal effects depend on the variable settings that correspond to the selected point at which this tangent line is drawn, so the marginal effect of a variable is not constant. Table 8 depicts the marginal effects of the factors. Marginal effect of any factor can be defined as the effect a positive or a negative coefficient has on the probabilities of the crash severity. For example, if we consider BETAWWRK (the crash location is between the advance warning sign and work area), the probability of the crash being fatal/major is 0.0595 higher (on average), the probability for the crash being a minor injury is 0.203 higher (on average), and the probability for the crash being a probable or unknown injury is 0.0917 higher (on average); whereas, the probability of the crash being a PDO is 0.3541 lower (on average). Thus, marginal effects portray the impact each factor has on the potential severity of the crash.
32
Table 8. Marginal effects of the factors along with their severities Probability of the factors causing possible/ unknown injury crashes
0.0917 0.082 -0.0716 -0.0851 -0.0398 -0.0445 0.0264 0.0635 0.0183 -0.0394 -0.049 0.0895 0.0793 0.0288 0.0781 0.06 0.0687 0.0499 0.0581 0.0653 0.0037 0.0557 0.056 0.0165 -0.0057
Significant variables affecting severity
BETAWWRK CLOUDY UNDDRI YONDRI MDDRI OLDRI VOLDRI NODAYLIT OFSMLDR OFSFMDR RAIN INTERSTA USROUTE SECROAD MUNIROAD IOWAROUT PSVEH PCKTRK VAN TRCKTRAC TRAFCONW VNOBSCUR WTHWRKZN LOCRAMP X16 Weighting Factors Total Weighting
Probability of the factors causing fatal-major crashes
0.0595 0.0564 -0.0087 -0.0119 -0.007 -0.0076 0.0065 0.0233 0.004 -0.0059 -0.0073 0.0152 0.102 0.1719 0.0924 0.1145 0.0132 0.0147 0.0202 0.0278 0.0007 0.0075 0.0092 0.0037 -0.0011
Probability of the factors causing minor crashes
0.203 0.1904 -0.064 -0.0815 -0.0436 -0.0481 0.0348 0.1039 0.0225 -0.0396 -0.0491 0.0948 0.2655 0.3069 0.2503 0.2679 0.0782 0.0723 0.0924 0.1164 0.0043 0.0529 0.059 0.0207 -0.0066
Probability of the factors causing PDO
-0.3541 -0.3288 0.1443 0.1784 0.0905 0.1002 -0.0677 -0.1907 -0.0448 0.0849 0.1054 -0.1995 -0.4468 -0.5076 -0.4208 -0.4423 -0.1601 -0.1368 -0.1708 -0.2095 -0.0088 -0.1161 -0.1242 -0.0409 0.0135
Weighted Average of the Probabilities of the factors causing several severe crashes
0.0672** 0.0629 -0.0219 -0.0276 -0.0144 -0.0159 0.0113 0.0336 0.0074 -0.0133 -0.0165 0.0316 0.0921 0.1185 0.0859 0.0949 0.0258 0.0234 0.0298 0.0377 0.0014 0.0179 0.0196 0.0067 -0.0022
4.5
3
2
1
10.5
Calculation of the Weighted Average of the Probability (example): 0.067242857** = (0.0595 × 4.5 + 0.203 × 3 + 0.917 × 2 - 0.3541 × 1) ÷ 10.5
33
To rank the factors in terms of their impact on severity, a weighted average technique was adopted. The weighted average of the probabilities of the factors is calculated to give an overall severity value. The different categories of the crashes are assigned ranking factors based on their importance and impact and they are as follows: ? ? ? ? ? Fatal – 5 Major Injury – 4 Minor Injury – 3 Probable/Unknown Injury – 2 PDO – 1
Given the fatal and major injury crashes have been combined, the average of the ranking factors 5 and 4 (4.5) is assigned to the Fatal/Major Injury crash category. Therefore, for this research, the ranking factors are as follows: ? ? ? ? Fatal/Major Injury – 4.5 Minor Injury – 3 Probable/Unknown Injury – 2 PDO – 1
The calculation of the weighted average for the probabilities is shown in Table 8. Figure 10 shows the distribution of the factors according to the weighted average of the probabilities for the occurrence of the different types of crashes, which is referred to as the severity of the factors in this report.
34
Weighted average of the Probabilities of the crashes to cause more FatalMajor, Minor, Probable/Unknown and a PDO
0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 -0.02 -0.04 BETAWWRK CLOUDY UNDDRI YONDRI MDDRI OLDRI VOLDRI NODAYLIT OFSMLDR OFSFMDR RAIN INTERSTA USROUTE SECROAD MUNIROAD IOWAROUT PSVEH PCKTRK VAN TRCKTRAC TRAFCONW VNOBSCUR WTHWRKZN LOCRAMP X16 Weighted average of the Probabilities of the crashes to more FatalMajor, Minor,Probable /Unknown and a PDO
Figure 10. Distribution of the weighted average for the probabilities of the factors for the occurrence of the different types of crashes The factors showing higher positive probabilities are more likely to cause a Fatal/Major Injury crash; whereas, those showing a negative probability indicate they are more likely to cause a PDO crash. To rank the factors on a scale of one to five based on the severity (5 being the most severe and 1 being the least severe), the probability distribution is categorized into five distinct levels: ? ? ? ? ? Less than 0 = 1 0 - 0.02 = 2 0.02 - 0.04 = 3 0.04 - 0.08 = 4 Greater than 0.08 = 5
Following this scale, the significant factors are ranked from most severe to least severe (generally from top to bottom) as shown in Table 9.
35
Table 9. Ranking of the factors according to severity Variable
USROUTE SECROAD MUNIROAD IOWAROUT BETAWWRK CLOUDY NODAYLIT INTERSTA PSVEH PCKTRK VAN TRCKTRAC VOLDRI OFSMLDR TRAFCONW VNOBSCUR WTHWRKZN LOCRAMP UNDDRI YONDRI MDDRI OLDRI OFSFMDR RAIN X16
Severity Ranking
5 5 5 5 4 4 3 3 3 3 3 3 2 2 2 2 2 2 1 1 1 1 1 1 1
Frequency Analysis and Factor Rating According to Frequency Risk is defined as the combined effect of the severity (i.e., the impact) and frequency (i.e., the likelihood of occurrence). Therefore, the impact the factors have on severity cannot by itself predict the magnitude of risk that those factors possess for O/M activities on the highways. Frequency of the factors plays a major role in determining the risk value of the factors and develops the Integrated Risk Management Model. The number of times that the factors are involved in each type of crash is illustrated in Table 10. Along with the frequencies of occurrence of the factors shown in Table 10, the frequency distribution is shown in Figure 11.
36
Table 10. Frequency distribution of the factors Significant Variables Affecting Severity BETAWWRK CLOUDY UNDDRI YONDRI MDDRI OLDRI VOLDRI NODAYLIT OFSMLDR OFSFMDR RAIN INTERSTA USROUTE SECROAD MUNIROAD IOWAROUT PSVEH PCKTRK VAN TRCKTRAC TRAFCONW VNOBSCUR WTHWRKZN LOCRAMP X16 Total Fatal/ Major Injury Crashes 97 83 26 51 491 485 146 117 336 263 99 600 455 184 19 64 433 294 189 323 311 1,038 1,056 17 865 Minor Injury Crashes 2,345 2,835 928 1,969 2,428 2,794 582 2,916 913 178 1,379 3,242 1,624 268 1,828 1,272 6,097 756 587 385 641 7,933 5,189 164 3,766 Possible Injury Crashes 3,038 1,131 458 1,615 4,516 4,687 1,277 562 1,529 850 359 6,798 1,474 1,513 1,144 486 5,652 1,721 1,540 910 1,125 10,551 6,857 877 6,163 Frequency Distribution (%) 16.63 11.29 5.94 22.44 34.99 33.04 6.41 11.79 15.87 10.02 16.33 63.05 13.06 5.45 11.37 6.80 54.29 13.99 10.26 7.72 9.12 91.64 69.21 5.45 51.24
PDO Crashes 3,675 2,165 1,859 8,715 11,825 10,220 1,525 2,897 5,956 4,224 7,154 24,065 3,633 1,035 3,268 1,922 17,702 4,928 3,334 2,630 2,941 30,919 24,995 1,941 17,412
Total 9,155 6,214 3,271 12,350 19,260 18,186 3,530 6,492 8,734 5,515 8,991 34,705 7,186 3,000 6,259 3,744 29,884 7,699 5,650 4,248 5,018 50,441 38,097 2,999 28,206 55,042
37
Frequency of the significant factors present in all the crashes Frequency of the significant factors present in all the crashes
100.00 90.00 80.00 70.00 60.00 50.00 40.00 30.00 20.00 10.00 0.00 BETAWWRK CLOUDY UNDDRI YONDRI MDDRI OLDRI VOLDRI NODAYLIT OFSMLDR OFSFMDR RAIN INTERSTA USROUTE SECROAD MUNIROAD IOWAROUT PSVEH PCKTRK VAN TRCKTRAC TRAFCONW VNOBSCUR WTHWRKZN LOCRAMP X16 Series1
Significant variables Figure 11. Distribution of the percentage frequency of the factors (crash database) present in all crashes involving intermittent and moving work zones and work on the shoulders and median To rank these significant factors according to their frequency of occurrence on a scale of one to five (1 being the least frequently occurring factor and 5 being the most frequently occurring factor), the percentage frequency scale is categorized into five levels as follows: ? ? ? ? ? 0 - 9.99 = 1 10.00 - 19.99 = 2 20.00 - 39.99 = 3 40.00 - 59.99 = 4 Greater than 60.00 = 5
Following this categorization protocol, the factors can be ranked according to their frequency of occurrence as shown in Table: 11.
38
Table 11. Ranking of significant factors according to their frequency of occurrence Frequency Variables Ranking INTERSTA 5 VNOBSCUR 5 WTHWRKZN 5 PSVEH 4 X16 4 YONDRI 3 MDDRI 3 OLDRI 3 BETAWWRK 2 CLOUDY 2 NODAYLIT 2 OFSMLDR 2 RAIN 2 USROUTE 2 MUNIROAD 2 PCKTRK 2 UNDDRI 1 VOLDRI 1 OFSFMDR 1 SECROAD 1 IOWAROUT 1 VAN 1 TRCKTRAC 1 TRAFCONW 1 LOCRAMP 1
Risk Rating of the Factors Risk can be defined mathematically as the product of the severity or impact of the factors and the frequency of occurrence of the factors. This combined estimate of the severity and frequency of occurrence gives an assessment of risk posed by the hazard and helps decision makers prioritize which hazards to address, assists in safety planning, and facilitates the development of risk mitigation strategies. Risk values are assigned to the significant factors as shown in Table 12.
39
Table 12. Risk values of the significant factors Severity Frequency Risk Variables Ranking Ranking Assessment INTERSTA 3 5 15 PSVEH 3 4 12 USROUTE 5 2 10 MUNIROAD 5 2 10 VNOBSCUR 2 5 10 WTHWRKZN 2 5 10 BETAWWRK 4 2 8 CLOUDY 4 2 8 NODAYLIT 3 2 6 PCKTRK 3 2 6 SECROAD 5 1 5 IOWAROUT 5 1 5 OFSMLDR 2 2 4 X16 1 4 4 YONDRI 1 3 3 MDDRI 1 3 3 OLDRI 1 3 3 VAN 3 1 3 TRCKTRAC 3 1 3 VOLDRI 2 1 2 RAIN 1 2 2 TRAFCONW 2 1 2 LOCRAMP 2 1 2 UNDDRI 1 1 1 OFSFMDR 1 1 1 Validation Survey Data Analysis Results In the validation survey, 33 responses were obtained, of which 24 were complete responses and nine were partial responses but missing answers to the open-ended questions. The responses were compiled in the form of percentages of participants selecting that particular category of a particular question. Table 13 illustrates the levels of probable severities and Table 14 illustrates the probable frequency of occurrence of the different factors (i.e., hazards), under activity, environment, equipment, and other, which the participants anticipated from their experiences.
40
Table 13. Severity levels of the factor Severity Weighted Average of the Severity 0.1280 0.0800 0.1700 0.1747 0.1460 0.2127 Potential Property Damage Minor Property Damage and/or Minor Injuries Major Property Damage and/or Major Injuries 4 0.22 0.06 0.26 0.22 0.28 0.16 0.19 0.26 0.19 0 0 0.19 0.22 0.31 0.16 0.34 0.11 0.26 0.27
ID Activity FWD structural testing on 1 pavement and subgrade Ride quality testing on 2 pavement or bridge surface 3 Core drilling on pavements Manual condition surveys for 4 pavement section Bridges and culvert repair and 5 inspection 6 Mowing Movement of street 7 sweeper/street cleaner Straddling painting (centerline 8 painting) Offset painting (edge-line 9 painting) on four-lane divided highway Offset painting (edge-line 10 painting) on two-lane twoway traffic roadway 11 Pavement markings 12 Crack filling/patch work 13 Curb and surface repairs 14 Flagger operations Replacing/repairing the 15 signals and signage Loading/unloading material 16 for maintenance operations on four-lane divided highway Loading/unloading material 17 for maintenance operations on two-lane two-way road
1 0.06 0.16 0.03 0.12 0.06 0.12 0.16 0.06 0.09
2 0.16 0.16 0.16 0.09 0.12 0.16 0.22 0.26 0.28
3 0.22 0.16 0.16 0.06 0.16 0.34 0.16 0.26 0.25
0.06 0.03 0.09 0.06 0.16 0.15 0.15
0.32 0.25 0.12 0.19 0.06 0.22 0.22
0.23 0.28 0.25 0.32 0.25 0.33 0.19
0.12
0.23
0.19
41
Catastrophic Loss/Fatality 5 0.06 0.06 0.03 0.16
No Loss
0.03 0.1347 0.06 0.1107 0.06 0.1467 0.03 0.1500 0.03 0.1327 0.06 0.1800 0.03 0.1540
0.06 0.1633
0.07 0.1580 0.07 0.1700
0.08 0.1753
Severity Weighted Average of the Severity 0.1433 0.1100 0.1800 0.1480 0.2133 Potential Property Damage Minor Property Damage and/or Minor Injuries Major Property Damage and/or Major Injuries 0.15 0.33 0.27 0.26 0.19 0.15 0.08 0.19 0.37 0.23 0.22 0.4 0.08 0.28 0.36
ID 18
Shoulder grading Repair, maintenance, and installation of guardrails, 19 cable rails, and barrier rails on four-lane divided highway Repair, maintenance, and installation of guardrails, 20 cable rails, and barrier rails on two-way two-lane road Repair, maintenance, and installation of centerline 21 guardrails, cable rails, and barrier rails on four-lane divided traffic roadway Maintenance of sanitary and 22 storm sewer and water main 23 Ditch cleaning Cleaning storm sewer intakes 24 and structures 25 Survey work Ingress and egress from 26 construction site Electric/power system 27 maintenance and street lighting 28 Snow removal Environment 29 Nighttime operations Presence of small towns or 30 schools nearby Improper signs and signage at 31 ramps and roadway intersections near work zones Pavement markings at 32 intersections at nighttime
0.12 0.04
0.31 0.22
0.27 0.19
0.04
0.31
0.12
0.11
0.22
0.19
0.07 0.23 0.24 0.3 0.15 0.04 0 0.04 0.2 0.08 0.12
0.41 0.35 0.28 0.19 0.04 0.35 0.22 0.08 0.24 0.08 0.08
0.04 0.04 0.08 0 0.33 0.12 0.3 0.16 0.24 0.28 0.24
42
Catastrophic Loss/Fatality 0 0 0 0 0.2
No Loss
0.07 0.1813
0.12 0.1800
0.07 0.1673
0.04 0.1313
0.04 0.1040 0.11 0.1327
0.04 0.1480
0.24 0.2320 0.04 0.1280
0.08 0.1893
Severity Weighted Average of the Severity 0.1573 0.1120 0.1360 0.0893 0.1627 0.0993 0.1733 0.0820 0.1053 0.1613 Potential Property Damage Minor Property Damage and/or Minor Injuries Major Property Damage and/or Major Injuries 0.16 0.32 0.6 0.33 0.36 0.2 0.28 0.4 0.2 0.08 0.13 0.18 0.09 0.22 0.09 0.17 0.26 0.26 0.22
ID 33 34 35 Pavement markings at intersections at daytime Work zones on roads in hilly areas Peak traffic hours Lack of knowledge about variable peak traffic time in local regions near work zone (e.g., variable travel patterns near institutions like the Iowa DOT, University, and Animal Disease Lab in Ames, Iowa) Work near railway crossings Clearing roadway for emergency vehicles Unforeseen weather conditions Fog and mist Different rules in shared jurisdictions Special events such as parades, races, and fairs in local cities and towns
0.12 0.08 0.08
0.2 0.04 0.04
0.4 0.36 0.2
36
0.08
0.04
0.33
37 38 39 40 41 42
0.12 0.16 0.12 0.08 0.16 0.16
0.16 0.12 0.28 0.08 0.24 0.24
0.08 0.32 0.16 0.32 0.08 0.36
Equipment 43 Falling-weight deflectometer 44 Straddling painters 45 Maintainers on gravel roads 46 Cold-mix patchwork 47 Friction testing 48 Media trucks Trucks carrying rock/ 49 aggregate 50 Boom trucks 51 Pick-up trucks
0.17 0.05 0.04 0.09 0.22 0.3 0.04 0.13 0.22
0.13 0.23 0.35 0.26 0.13 0.3 0.22 0.22 0.22
0.13 0.32 0.13 0.22 0.13 0 0.3 0.17 0.17
43
Catastrophic Loss/Fatality 0 0 0 0 0.05 0 0.09 0 0 0
No Loss
0.16 0.2213 0.08 0.2373
0.08 0.1913
0.12 0.1813 0.04 0.1573 0.12 0.1920 0.12 0.2267
0.04 0.1547 0 0.1367
Severity Weighted Average of the Severity 0.1353 0.1093 0.1153 0.1220 Potential Property Damage Minor Property Damage and/or Minor Injuries Major Property Damage and/or Major Injuries 0.17 0.13 0.22 0.36 0.3 0.26 0.17 0.04 0.17 0.22 0.22 0.13 0.14 0.3
ID 52 53 54 55 56 57 Other 58 59 60 61 62 63 64 65
Street sweepers/street cleaners 0.13 Jet vac Paint carts (hauled on trailers) Absence of proper signage near work zone Absence of fluorescent diamond signs Not using lights/blinkers in work zone Lack of coordination with municipalities Work done under full closure Lack of coordination between state and local agencies Lack of work safety and training programs Absence of train-the-trainers philosophy Lack of coordination between DOT and utilities regarding control of ROW Improper third-party interaction Not imposing speed limit fines on public 0.17 0.13 0.09 0.13 0.09
0.22 0.22 0.3 0 0.09 0.17
0.26 0.17 0.04 0.23 0.26 0.17
0.26 0.57 0.26 0.09 0.17 0.35 0.18 0.09
0.13 0.13 0.09 0.04 0.04 0.09 0.14 0.09
0.26 0.13 0.26 0.26 0.22 0.17 0.27 0.26
44
Catastrophic Loss/Fatality 0 0 0 0
No Loss
0.27 0.2380 0.13 0.1960 0.22 0.2053
0.04 0.1453 0.13 0.1353 0.04 0.1400 0.35 0.2387 0.22 0.1927 0.04 0.1173
0.22 0.2233
Table 14. Frequency distribution of the factors Frequency Very Probable 5 0 0 0 0 0 0 0 0.06 0.03 0.1120 0.1080 0.1300 0.1053 0.1413 0.1240 0.1380 0.1967 0.1733 0.03 0.03 0 0 0.06 0.04 0.11 0.08 Very Unlikely Weighted Average of Likelihood of Occurrence 0.1640 0.1720 0.1733 0.1540 0.1947 0.1560 0.1760 0.1913
ID Activity FWD structural testing on 1 pavement and subgrade Ride quality testing on 2 pavement or bridge surface 3 Core drilling on pavements Manual condition surveys for 4 pavement section Bridges and culvert repair and 5 inspection 6 Mowing Movement of street 7 sweeper/street cleaner Straddling painting (centerline 8 painting) Offset painting (edge-line 9 painting) on four-lane divided highway Offset painting (edge-line 10 painting) on two-lane two-way traffic roadway 11 Pavement markings 12 Crack filling/patch work 13 Curb and surface repairs 14 Flagger operations Replacing/repairing the signals 15 and signage Loading/unloading material for 16 maintenance operations on four-lane divided highway Loading/unloading material for 17 maintenance operations on two-lane two-way road
1 0.12 0.12 0.09 0.1 0.07 0.19 0.12 0.03 0.1
2 0.12 0.19 0.25 0.19 0.23 0.29 0.19 0.26 0.19
3 0.28 0.16 0.16 0.06 0.13 0.19 0.19 0.1 0.23
4 0.12 0.16 0.22 0.23 0.3 0.13 0.25 0.45 0.32
0.06 0.06 0.12 0.03 0.12 0.11 0.07
0.25 0.16 0.09 0.23 0.12 0.3 0.3
0.25 0.31 0.22 0.3 0.34 0.33 0.22
0.25 0.28 0.41 0.23 0.31 0.11 0.19
0.08
0.23
0.23
0.31
45
Probable
Unlikely
Neutral
Frequency Very Probable 0 0 0 0 0 0 0 0.04 0.04 0 0 0.17 0.04 0.16 0.16 0.04 Very Unlikely Weighted Average of Likelihood of Occurrence 0.1307 0.1587 0.1633 0.1580 0.1187 0.0993 0.1160 0.1293 0.2020 0.1300 0.1727 0.2507 0.1547 0.2267 0.2240 0.1893
ID 18
Shoulder grading Repair, maintenance, and installation of guardrails, cable 19 rails, and barrier rails on fourlane divided highway Repair, maintenance, and installation of guardrails, cable 20 rails, and barrier rails on twoway two-lane road Repair, maintenance, and installation of centerline 21 guardrails, cable rails, and barrier rails on four-lane divided traffic roadway Maintenance of sanitary and 22 storm sewer and water main 23 Ditch cleaning Cleaning storm sewer intakes 24 and structures 25 Survey work Ingress and egress from 26 construction site Electric/power system 27 maintenance and street lighting 28 Snow removal Environment 29 Nighttime operations Presence of small towns or 30 schools nearby Improper signs and signage at 31 ramps and roadway intersections near work zones Pavement markings at 32 intersections at nighttime Pavement markings at 33 intersections at daytime
0.07 0.07
0.37 0.22
0.33 0.37
0.04 0.19
0.07
0.22
0.3
0.26
0.11
0.11
0.48
0.15
0.11 0.22 0.15 0.22 0.04 0.12 0 0 0 0.12 0 0.04
0.33 0.33 0.35 0.15 0.15 0.19 0.11 0.04 0.32 0 0.08 0.04
0.19 0.11 0.19 0.26 0.19 0.23 0.15 0.17 0.28 0.08 0.16 0.52
0.11 0.07 0.08 0.11 0.48 0.19 0.48 0.58 0.16 0.56 0.48 0.24
46
Probable
Unlikely
Neutral
Frequency Very Probable 0.12 0.24 0.12 0.04 0.17 0.16 0.24 0.12 0.12 0 0 0 0 0 0 0.04 0 0 0 0 0.04 Very Unlikely Weighted Average of Likelihood of Occurrence 0.2420 0.2773 0.2153 0.1627 0.2013 0.2293 0.2533 0.1547 0.1947 0.0993 0.1760 0.1053 0.1587 0.0860 0.1213 0.1607 0.1467 0.1320 0.1413 0.1240 0.1447
ID 34 35 Work zones on roads in hilly areas Peak traffic hours Lack of knowledge about variable peak traffic time in local regions near work zone (e.g., variable travel patterns near institutions like the Iowa DOT, University, and Animal Disease Lab in Ames, Iowa) Work near railway crossings Clearing roadway for emergency vehicles Unforeseen weather conditions Fog and mist Different rules in shared jurisdictions Special events such as parades, races, and fairs in local cities and towns 0 0
0 0
0.29 0.08
0.54 0.68
36
0.08
0.04
0.21
0.46
37 38 39 40 41 42
0.12 0 0.04 0.04 0.12 0.08
0.16 0.17 0.08 0.08 0.08 0
0.28 0.17 0.28 0.16 0.16 0.48
0.24 0.33 0.4 0.48 0.24 0.2
Equipment 43 Falling-weight deflectometer 44 Straddling painters 45 Maintainers on gravel roads 46 Cold-mix patchwork 47 Friction testing 48 Media trucks Trucks carrying rock/ 49 aggregate 50 Boom trucks 51 Pick-up trucks 52 53 54 Street sweepers/street cleaners Jet vac Paint carts (hauled on trailers)
0.04 0.04 0 0.09 0.17 0.3 0.13 0.13 0.17 0.13 0.14 0.13
0.13 0.13 0.26 0.22 0.09 0.09 0.13 0.17 0.39 0.22 0.14 0.13
0.17 0.26 0.3 0.39 0.26 0.22 0.26 0.35 0.17 0.17 0.36 0.3
0.17 0.39 0.04 0.17 0.04 0.17 0.26 0.17 0.13 0.26 0.09 0.17
47
Probable
Unlikely
Neutral
Frequency Very Probable 0.26 0.14 0.17 0.04 0.09 0.09 0.43 0.23 0.04 0.05 0.23 Very Unlikely Weighted Average of Likelihood of Occurrence 0.2600 0.2093 0.2313 0.1913 0.1307 0.1840 0.2467 0.2120 0.1680 0.1907 0.2493
ID 55 56 57 Other 58 59 60 61 62 63 64 65 Lack of coordination with municipalities Work done under full closure Lack of coordination between state and local agencies Lack of work safety and training programs Absence of train-the-trainers philosophy Lack of coordination between DOT and utilities regarding control of ROW Improper third-party interaction Not imposing speed limit fines on public Absence of proper signage near work zone Absence of fluorescent diamond signs Not using lights/blinkers in work zone
0.04 0.09 0.04
0 0.05 0.04
0.04 0.27 0.26
0.61 0.36 0.43
0.04 0.39 0.04 0.09 0.05 0.13 0 0
0.13 0.48 0.17 0 0.14 0.13 0.14 0.05
0.39 0 0.35 0.26 0.14 0.35 0.23 0.23
0.3 0.04 0.22 0.17 0.32 0.22 0.41 0.45
Analysis of Severity and Ranking of the Factors The severity is analyzed by calculating a weighted average of the five levels of severity. The weight is assigned to the factors based on their importance and level of severity as follows: ? ? ? ? ? No Loss = 1 Potential Property Damage = 2 Minor Property Damage and/or Minor Injuries = 3 Major Property Damage and/or Major Injuries = 4 Catastrophic Loss/Fatality = 5
48
Probable
Unlikely
Neutral
The weighting is used to create a severity index score that can be used to rank the factors according to the associated severity of the crashes. The weighted average of the severity is calculated in the following way: Weighted average of severity (FWD Structural Testing on Pavement and Subgrade) = (0.06 × 1 + 0.16 × 2 + 0.22 × 3 + 0.22 × 4 + 0.0 × 5) ÷ 15 = 0.1280 Figure 12 shows the distribution of the factors graphically according to the weighted average of the severity levels. According to this distribution, the factors are ranked on a Likert scale from 1 to 5 (with 1 being the least severe and 5 being the most severe): ? ? ? ? ? Less than 0.1 = 1 0.10 - 0.15 = 2 0.15 - 0.20 = 3 0.20 - 0.25 = 4 0.25 - 0.30 = 5
Based on the distribution of the factors according to the severity levels as shown in Figure 12 and the categories as defined above, the factors were ranked according to severity, which is shown in Table 15.
49
Figure 12. Distribution of the severity levels of the factors (crash database) present in all crashes involving intermittent and moving work zones and work on the shoulders and median
50
Table 15. Ranking of the factors according to severity Activity Flagger operations Mowing Straddling painting (centerline painting) Offset painting (edge-line painting) on four-lane divided highway Offset painting (edge-line painting) on two-lane two-way traffic roadway Pavement markings Crack filling/patch work Replacing/repairing the signals and signage Loading/unloading material for maintenance operations on four-lane divided highway Loading /unloading material for maintenance operations on two-lane two-way road Repair, maintenance, and installation of guardrails, cable rails, and barrier rails on two-lane two-way road Repair, maintenance, and installation of guardrails, cable rails, and barrier rails on four-lane divided highway Repair, maintenance, and installation of centerline guardrails, cable rails, and barrier rails on four-lane divided traffic roadway Ingress and egress from construction site FWD structural testing on pavement and subgrade Movement of street sweeper/street cleaner Core drilling on pavements Manual condition surveys for pavement section Bridges and culvert repair and inspection Curb and surface repairs Shoulder grading Maintenance of sanitary and storm sewer and water main Ditch cleaning Cleaning storm sewer intakes and structures Survey work Electric/power system maintenance and street lighting Snow removal Ride quality testing on pavement or bridge surface Environment Nighttime operations Improper signs and signage at ramps and roadway intersections near work zones Work zones on roads in hilly areas Peak traffic hours Fog and mist Pavement markings at intersections at nighttime Pavement markings at intersections at daytime Severity 4 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 2 2 1 Severity 4 4 4 4 4 3 3
51
Lack of knowledge about variable peak traffic time in local regions near work zone (e.g., variable travel patterns near institutions like the Iowa DOT, University, and Animal Disease Lab in Ames, Iowa) Work near railway crossings Clearing roadway for emergency vehicles Unforeseen weather conditions Presence of small towns or schools nearby Different rules in shared jurisdictions Special events such as parades, races, and fairs in local cities and towns Equipment Absence of proper signage near the work zone Not using lights/blinkers in the work zone Absence of fluorescent diamond signs Straddling painters Trucks carrying rock/aggregate Cold-mix patchwork Boom trucks Media trucks Pick-up trucks Street sweepers/street cleaners Jet vac Paint carts (hauled on trailers) Falling-weight deflectometer Maintainers on gravel roads Friction testing Other Lack of work safety and training programs Not imposing speed limit fines on public Absence of train-the-trainers philosophy Lack of coordination with municipalities Work done under full closure Lack of coordination between state and local agencies Lack of coordination between DOT and utilities regarding control of ROW Improper third-party interaction Analysis of Frequency
3 3 3 3 2 2 2 Severity 4 4 3 3 3 3 3 2 2 2 2 2 1 1 1 Severity 4 4 3 2 2 2 2 2
Weighted average of the frequency of occurrence of the different factors is also calculated to rank the factors on the same scale according to their likelihood of occurrence. The weighted average of the frequency/likelihood of occurrence is calculated as follows: Weighted average of frequency (FWD Structural Testing on Pavement and Subgrade) = (0.12 × 1 + 0.12 × 2 + 0.28 × 3 + 0.12 × 4 + 0.0 × 5) ÷ 15 = 0.1120
52
Figure 13 shows the distribution of the factors graphically according to the weighted frequency. According to this distribution, the factors are ranked on a Likert scale from 1 to 5 (with 1 being the least frequent and 5 being the most frequent): ? ? ? ? ? Less than 0.1 = 1 0.10 - 0.15 = 2 0.15 - 0.20 = 3 0.20 - 0.25 = 4 0.25 - 0.30 = 5
Based on the distribution of the factors according to the frequencies shown in Figure 13 and the categories defined above, the factors are ranked according to frequency as shown in Table 16.
53
Figure 13. Distribution of the percentage frequency of the factors (crash database) present in all crashes involving intermittent and moving work zones and work on the shoulders and median
54
Table 16. Ranking of the factors according to frequency Activity Ingress and egress from construction site Straddling painting (centerline painting) Offset painting (edge-line painting) on four-lane divided highway Offset painting (edge-line painting) on two-lane two-way traffic roadway Pavement markings Crack filling/patch work Curb and surface repairs Flagger operations Replacing/repairing the signals and signage Loading /unloading material for maintenance operations on four-lane divided highway Loading /unloading material for maintenance operations on two-lane two-way road Repair, maintenance, and installation of guardrails, cable rails, and barrier rails on four-lane divided highway Repair, maintenance, and installation of guardrails, cable rails, and barrier rails on two-way two-lane road Repair, maintenance, and installation of centerline guardrails, cable rails, and barrier rails on four-lane divided traffic roadway Snow removal FWD structural testing on pavement and subgrade Ride quality testing on pavement or bridge surface Core drilling on pavements Manual condition surveys for pavement section Bridges and culvert repair and inspection Mowing Movement of street sweeper/street cleaner Shoulder grading Cleaning storm sewer intakes and structures Survey work Electric/power system maintenance and street lighting Maintenance of sanitary and storm sewer and water main Ditch cleaning Environment Nighttime operations Peak traffic hours Improper signs and signage at ramps and roadway intersections near work zones Pavement markings at intersections at nighttime Work zones on roads in hilly areas Lack of knowledge about variable peak traffic time in local regions near work zone (e.g., variable travel patterns near institutions like the Iowa DOT, University, and Animal Disease Lab in Ames, Iowa) Clearing roadway for emergency vehicles Frequency 4 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 2 1 Frequency 5 5 4 4 4 4 4
55
Unforeseen weather conditions Fog and mist Presence of small towns or schools nearby Pavement markings at intersections at daytime Work near railway crossings Different rules in shared jurisdictions Special events such as parades, races, and fairs in local cities and towns Equipment Absence of proper signage near the work zone Absence of fluorescent diamond signs Not using lights/blinkers in the work zone Straddling painters Cold-mix patchwork Trucks carrying rock/aggregate Maintainers on gravel roads Media trucks Boom trucks Pick-up trucks Street sweepers/street cleaners Jet vac Paint carts (hauled on trailers) Falling-weight deflectometer Friction testing Other Lack of work safety and training programs Absence of train-the-trainers philosophy Not imposing speed limit fines on public Lack of coordination with municipalities Lack of coordination between state and local agencies Lack of coordination between DOT and utilities regarding control of ROWs Improper third-party interaction Work done under full closure Risk Rating of the Factors
4 4 3 3 3 3 3 Frequency 5 4 4 3 3 3 2 2 2 2 2 2 2 1 1 Frequency 4 4 4 3 3 3 3 2
Similar to crash data analysis, the risk assessment value of the hazards/factors identified in the survey is calculated by multiplying the frequency rating and the severity rating of the hazards. Thereby, the risk assessment value of the factors ranges from 1 (1×1) to 25 (5×5), which is the same as that of the risk assessment value range obtained from the crash data analysis. Thus, the same Integrated Risk Management Model can be used to assess the identified risks obtained from both the crash data and the survey data as shown in Table 17.
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Table 17. Ranking of the factors according to risk assessment value Activities Flagger operations Ingress and egress from construction site Straddling painting (centerline painting) Offset painting (edge-line painting) on four-lane divided highway Offset painting (edge-line painting) on two-lane two-way traffic roadway Pavement markings Crack filling/patch work Replacing/repairing the signals and signage Loading /unloading material for maintenance operations on four-lane divided highway Loading /unloading material for maintenance operations on two-lane two-way road Repair, maintenance, and installation of guardrails, cable rails, and barrier rails on four-lane divided highway Repair, maintenance, and installation of guardrails, cable rails, and barrier rails on two-way two-lane road) Repair, maintenance, and installation of centerline guardrails, cable rails, and barrier rails on four-lane divided traffic roadway) Mowing Curb and surface repairs Snow removal FWD structural testing on pavement and subgrade Shoulder grading Core drilling on pavements Manual condition surveys for pavement section Bridges and culvert repair and inspection Maintenance of sanitary and storm sewer and water main Movement of street sweeper/street cleaner Cleaning storm sewer intakes and structures Survey work Electric/power system maintenance and street lighting Ride quality testing on pavement or bridge surface Ditch cleaning Environment Night time operations Peak traffic hours Improper signs and signage at ramps and roadway intersections near work zones 57 Frequency 1 3 4 3 3 3 3 3 3 3 3 3 3 3 2 3 3 2 2 2 2 2 2 2 2 2 2 2 1 Frequency 1 5 5 4 Severity 2 4 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 2 1 2 Severity 2 4 4 4 Risk Value 1×2 12 12 9 9 9 9 9 9 9 9 9 9 9 6 6 6 4 4 4 4 4 4 4 4 4 4 2 2 Risk Value 1×2 20 20 16
Work zones on roads in hilly areas Fog and mist Pavement markings at intersections (at nighttime) Lack of knowledge about variable peak traffic time in local regions near work zone (e.g., variable travel patterns near institutions like the Iowa DOT, University, and Animal Disease Lab in Ames, Iowa) Clearing roadway for emergency vehicles Unforeseen weather conditions Pavement markings at intersections at daytime Work near railway crossings Presence of small towns or schools nearby Different rules in shared jurisdictions Special events such as parades, races, and fairs in local cities and towns Equipment Absence of proper signage near the work zone Not using lights/blinkers in the work zone Absence of fluorescent diamond signs Straddling painters Cold-mix patchwork Trucks carrying rock/aggregate Boom trucks Media trucks Pick-up trucks Street sweepers/street cleaners Jet vac Paint carts (hauled on trailers) Maintainers on gravel roads Friction testing Falling-weight deflectometer Other Not imposing speed limit fines on public Lack of work safety and training programs Absence of train-the-trainers philosophy Lack of coordination with municipalities Lack of coordination between state and local agencies Lack of coordination between DOT and utilities regarding control of ROWs Improper third-party interaction Work done under full closure
4 4 4 4 4 4 3 3 3 3 3 Frequency 1 5 4 4 3 3 3 2 2 2 2 2 2 2 1 1 Frequency 1 4 4 4 3 3 3 3 2
4 4 3 3 3 3 3 3 2 2 2 Severity 2 4 4 3 3 3 3 3 2 2 2 2 2 1 1 1 Severity 2 4 4 3 2 2 2 2 2
16 16 12 12 12 12 9 9 6 6 6 Risk Value 1×2 20 16 12 9 9 9 6 4 4 4 4 4 2 1 1 Risk Value 1×2 16 16 12 6 6 6 6 4
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The results are analyzed and explained in the final section of this report (Discussion and Implications of the Results.) Development of the Integrated Risk Management Model A risk matrix was developed as part of the risk assessment process as a metric representing the association of significant factors to severity and frequency of crashes. In the development of the Integrated Risk Management Model, the significant factors were termed hazards to be consistent with prior research on risk. A hazard is a condition (e.g., blowing snow or excessive speed) that contributes to a loss event, either as the proximate cause of the loss or as a contributing factor. A risk of loss can be represented as the total of each of the hazards (factor) that contribute to it. The risk associated with any particular hazard, H, can be defined as its probability or likelihood of occurrence (i.e., the frequency), p, multiplied by its severity, c. Stated simply, the risk associated with any single hazard is the product of how likely it is to happen and how bad it would be if it did happen, as represented in the following equation. Hazard = PH × CH The total risk, R, of a loss event, e, is the sum of the n potential hazards that would result in that event:
The severity of the factors is obtained from the weighted average of the marginal effects of the statistical model, and, the frequency or likelihood of occurrence of the factors is obtained from the descriptive statistics. The best tool to assess the risk of the hazards in such a scenario is to develop a risk assessment matrix. A risk assessment matrix is a two-dimensional representation of the frequency or likelihood of occurrence of the hazards on one scale (frequency scale) and the severity or consequence of those hazards on the other scale (severity scale). The frequency scale is on the vertical axis and the severity scale is on the horizontal axis. Both the scales are marked from 1 to 5. Thus, the risk assessment matrix (Figure 14) measures the risk of the hazards on a scale of 1 (1×1) to 25 (5×5).
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5 5
10
15
20
25
1 to 3
Negligible Risk Potential
4 Frequency 4
8
12
16
20
4 to 5
Marginal Risk Potential
3 3
6
9
12
15
6 to 9
Moderate Risk Potential
2 2
4
6
8
10
10 to 12
Critical Risk Potential Catastrophic Risk Potential
1 1 1
2 2
3 3 Severity
4 4
5 5
15 to 25
Figure 14. Risk assessment matrix As shown, this scale is categorized into five levels, depending on the magnitude or overall effect of the risk: ? ? ? ? ? Negligible Risk Potential – Risk value ranging from 1 to 3 Marginal Risk Potential – Risk value ranging from 4 to 5 Moderate Risk Potential – Risk value ranging from 6 to 9 Critical Risk Potential – Risk value ranging from 10 to 12 Catastrophic Risk Potential – Risk value ranging from 15 to 25
The color-coded risk assessment matrix is a very useful technique to determine the potential risk of the hazards already identified from the crash database analysis. This matrix should be used in conjunction with Table 12 and Table 17, which contain the identified significant factors generated from the Iowa DOT statewide crash data analysis along with the combined hazard value and also the factors identified from the survey data analysis, respectively. Any hazard present in a risk event can be assessed in the following way: Say, for example, the factor BETAWWRK, from the crash database, has a hazard value of 8, which means the location between the advance warning sign and work area bears a moderate risk potential and a crash occurring within this region would likely be a moderately severe crash. On the other hand, the factor WTHWRKZN has a hazard value of 10, which means the location within or adjacent to the work activity bears critical risk potential and the crashes occurring within this zone is more likely to be severe than the other location. Hence, the second location needs to be closely monitored and proper traffic control measures need to be taken to avoid crashes within this location.
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The risk assessment matrix helps in prioritizing the different hazards and thereby helps in planning risk mitigation strategies. Given that a “typical” crash is assumed to have both the frequency and severity ranked as 3, the combined value of 9 (3×3) marked the boundary for moderate risk potential. Anything greater than this value was considered as having critical or catastrophic risk potential.
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DISCUSSION OF KEY FINDINGS Crash Data Analysis Six factors were assessed with a hazard value greater than 9 as follows: ? ? ? ? ? ? Interstate route US route Municipal route Passenger vehicle Vision not obscured by moving vehicles or frosted windows/windshield, blowing snow, or fog/smoke/dust Region located within or adjacent to the work activity
The researchers found that the routes of travel are extremely critical from the overall risk point of view. According to the methodology of this research, these hazards should be determined to have the top-most priority while planning for mitigation strategies. Some reasons for significance of the routes of travel are likely higher speeds on interstates and US highways and inadequate/improper traffic control systems not coordinated with the actual location of the mobile operations. The analysis shows interesting results in terms of location of the crash. It describes the region located within or adjacent to the work activity bears critical or catastrophic risk potential and severe crashes are more likely to occur within this zone. This indicates that proper traffic control measures may not be in use near or within the mobile work zones, or that traffic control may be keeping pace with the moving operations. Proper safety rules need to be followed in those regions. In addition to the above mentioned factors, those hazards having a value of 5 on either the severity scale or the frequency scale need attention. Four factors were assessed with a value of 5 in the severity scale as follows: ? ? ? ? US route Secondary route Municipal route Iowa route
On these routes, the crashes that are occurring are mostly severe crashes.
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Three factors are assessed with a value of 5 in the frequency scale as follows: ? ? ? Vision not obscured by moving vehicles or frosted windows/windshield, blowing snow, or fog/smoke/dust Interstate route Region located within or adjacent to the work activity
Most of the crashes related to the maintenance and mobile operations work zone occur when vision is not obscured by moving vehicles or frosted windows/windshield, blowing snow, or fog/smoke/dust. This is because, if the vision is not obscured by any obstruction, most likely the vehicles will drive at a higher speed. If coming upon a mobile work zone like lane painting or guardrail repairs, it may then happen that the vehicles are unable to control their speed and end up traveling into the work zone causing a crash. The Interstate route is also another important factor in terms of frequency of crashes taking place. About 63 percent of the crashes take place on the interstates. Because crashes on virtually all types of routes were determined to be severe by the model, the researchers suspected the model may be over-specified in terms of route types. Therefore, the model was re-run (model 2) eliminating state and local routes from the analysis. The most interesting change is in the severity result related to the Interstate route, which went down from a severity ranking of 3 in the first model to a severity ranking of 1 in model 2. The frequency ranking (of 5) remained the same. When state and municipal routes were deleted from the final model, the Interstate route had a negative marginal effect instead of a high positive value, as was the case in the initial model. This change suggests that a crash on an interstate is actually more likely to be a PDO crash and contrasts with the results from the initial model, which suggested that crashes on all routes were likely to be severe. Thus, the initial observation that higher speed limits on interstates were causing more severe work-zone crashes appears to be in doubt. An alternative explanation is that, given the study focused on work-zone crashes only, where speeds are reduced, and variation in travel speeds are likely to be minimized, interstates are actually safer due to their superior design parameters compared to other routes and are also better maintained, generally speaking. Interstate mobile work zones almost always maintain a minimum of two divided lanes in each direction, whereas, other routes are frequently head-tohead traffic. In other words, the interstates provide more space (in terms of number of lanes) for the vehicles to pass by the mobile work zone than that of other routes. Similarly, the region located within or adjacent to the mobile work activity is critical in terms of the frequency of the crashes. Most of the crashes are likely to occur within or adjacent to the work activity, indicating that proper traffic control systems and safety rules are important.
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Validation Survey Data Analysis In the validation survey, factors (or hazards) were categorized as follows: ? ? ? ? Activity Environment Equipment Other
The factors within each category are ranked in the descending order of the magnitude of the severity, frequency, and risk assessment value in Tables 14, 16 and 17, respectively. The Integrated Risk Management Model helps in prioritizing the different identified factors (or hazards) when used in conjunction with the risk assessment values of the factors as shown in Table 17. The hazards with a risk assessment value (i.e., the combined value of severity and frequency) greater than 9 (i.e., hazards bearing critical or catastrophic risk potential) are as follows: Activity ? Flagger operations ? Ingress and egress from construction site Environment ? Nighttime operations ? Peak traffic hours ? Improper signs and signage at ramps and roadway intersections near work zones ? Work zones on roads in hilly areas ? Fog and mist ? Pavement markings at intersections at nighttime ? Lack of knowledge about variable peak traffic time in local regions near work zone (e.g., variable travel patterns near institutions like the Iowa DOT, University, and Animal Disease Lab in Ames, Iowa) ? Clearing roadway for emergency vehicles ? Unforeseen weather conditions Equipment ? Absence of proper signage near the work zone ? Not using lights/blinkers in the work zone ? Absence of fluorescent diamond signs Other ? Not imposing speed limit fines on public ? Lack of Work safety and training programs ? Absence of train-the-trainers philosophy
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The nine hazards that are in the red zone with catastrophic risk potential (among all the factors and under all the categories) are as follows: ? ? ? ? ? ? ? ? ? Nighttime operations Peak traffic hours Absence of proper signage near the work zone Improper signs and signage at ramps and roadway intersections near work zones Work zones on roads in hilly areas Fog and mist Not using lights/blinkers in the work zone Not imposing speed limit fines on public Lack of work-safety and training programs
According to the validation survey results, the hazards mentioned above are most likely to cause very serious (or catastrophic) crashes due to the operations and maintenance activities. Of the 65 hazards that were identified from the expert panel discussion, only three hazards have been assessed in the survey with a frequency score of 5: ? ? ? Nighttime operations Peak traffic hours Absence of proper signage near the work zone
None of the hazards scored 5 for severity. The survey respondents appear to perceive that most of the crashes due to O/M activities occur when the operations are carried out during nighttime and during peak traffic hours. Absence of proper signage near the work zone is perceived as another major cause of crashes. The potential hazards related to crash risks during O/M activities were identified through expert panel discussions and literature reviews, analyzed through statistical modeling of quantitative crash data and determination of perceptual data obtained through a national survey, and assessed by developing an integrated risk model and risk value assignments.
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Identification of Risk Mitigation Strategies The final step in the research study was to develop relevant mitigation strategies for potential adoption in mobile work zones. The results of the expert-panel brainstorming workshop, follow-up in-depth interviews with three members of the panel, analysis of the crash database, and perceptions from a national survey suggest the following risk mitigation strategies may be helpful in reducing the severity and frequency of crashes in mobile work zones associated with O/M activities. 1. Revise and integrate the Iowa DOT Instructional Memorandums (IM), Traffic and Safety Manual, and Standard Road Plans – TC Series (traffic control diagrams) and related notes to provide clear, comprehensive, and easily-accessible guidance on placement of traffic control measures for mobile work zones. 2. Consider expanding traffic-control options to include proven technologies such as the Balsi Beam, portable rumble strips, blue strobe lights, and other innovations. Traffic-control specifications and associated allocation of risk between contractors and state/local agencies would also need to be revised to encourage adoption of new traffic-control measures. This is an area where a follow-up study would prove beneficial. 3. Investigate new delivery technologies (such as Skype, webinars, and remote conferencing) to allow for improved training within the flattened structure of the Iowa DOT. The training should include both formal programs for centralized functions and informal weekly programs for supervisory personnel to discuss issues with field crews. The Local Technical Assistance Program (LTAP) at the Institute for Transportation (InTrans) may be of assistance in developing such a safety-training program. The safety-training program will be particularly helpful for new and temporary employees working in mobile operations. 4. Written manuals and training programs should focus on the importance of worker and equipment visibility and advance warning systems, especially in high-speed environments (interstates and US highways) and those where drivers may be distracted more easily by pedestrians, traffic signals, bicyclists, etc., such as municipal streets. 5. Schedule Best Practices meetings regularly within divisions. Encourage shop management to meet with division managers and other shop managers to discuss best practices that are discovered in the field, especially when it comes to safety. Division managers should also hold meetings periodically to encourage this type of information sharing. The alternative delivery technologies mentioned above may also be helpful in disseminating best practices. 6. Certain environments should be reviewed to ensure that the minimum number of workers and vehicles are used in the traffic-control system. Specifically, two lane two-way highways, work at railroads and other utility sites, overhead work, and work on bridges are likely highrisk environments where additional vehicles and workers increase the risk of crashes. The
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value of impact attenuators should be researched to determine the safety benefits of such equipment. The analysis of the crash database did not find any reports of impact attenuators associated with mobile work-zone crashes. 7. Policies and safety training programs should emphasize the need for locating traffic controls at the appropriate distance from the work site to allow for driver reactions, and traffic controls should be moved at the same pace as the mobile operations whenever possible. Research Limitations The limitations of this research study are as follows. ? All of the factors/hazards that were studied in this research could not be described by the crash database variables queried. Representative variables were selected and analyzed from the crash database, which indirectly explained the effect of the required variables/factors/hazards. The data entered on the responding officer’s report does not always match the variable of interest. The crash data were drawn from the Iowa crash database, but the survey and literature review was national in scope. This made the research study somewhat biased. To get a good sample size, crash data from the last 10 years (2001 through 2010) were analyzed. This may have included information about several crashes that occurred after changes in work-zone signage practices and other infrastructure development. The response rate for the validation survey was low. Because of the sample size, no statistical analysis could be performed.
?
?
?
Implementation Readiness The possible mitigation strategies developed as a result of this research are not field-tested, as it was out of the scope of this research project. If further research on the implementation ideas is needed, a separate research study can be conducted focusing on the implementation of the riskmitigation techniques found as a result of this study. Testing may include evaluation of the riskmitigation strategies in simulators or actual field situations to determine effectiveness.
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Implementation Benefits The research findings are intended to provide a process map or guidebook outline for use by the Iowa DOT, Iowa county engineers, and municipal transportation agencies to assess the risk potential of various O/M activities and develop team-based risk-mitigation strategies. The primary benefits of this research are the reduced risk of injury, fatality, and property damage for O/M workers and the traveling public. The research results can be implemented by the Iowa DOT staff, county engineers, municipal transportation directors, and any other transportation professionals responsible for O/M activities, including field personnel. The results can also be used as a standard process for identifying highest-risk O/M activities and developing mitigation strategies to reduce those risks. However, it should be noted that the riskmitigation processes developed and envisioned in this research are highly inclusive, involving state, local, and regional professionals from both field and office positions. Intuitively, any process that decreases risk should improve worker safety, lower agency costs, improve service to the traveling public, and lead to more-efficient procedures over the long-term, although these specific performance benefits are not assessed directly as part of this research project.
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REFERENCES Blincoe, L., A. Seay, E. Zaloshnja, T. Miller, E. Romano, S. Luchter, and R. Spicer. 2002. The Economic Impact of Motor Vehicle Crashes: 2000. National Highway Traffic Safety Administration (NHTSA). Report No. DOT HS 809 446. May 2002. Goodwin, L. C. 2003. Best Practices for Road Weather Management. Weather. May 2003. Iowa DOT. 2001. Investigating Officer’s Accident Reporting Guide. Iowa Department of Transportation. Motor Vehicle Division. Office of Driver Services. January 2001. (Code sheet available at:http://www.iowadot.gov/mvd/ods/accidents.htm.) Juni, E., T. M. Adams, and D. Sokolowski. 2008. Relating Cost to Condition in Routine Highway Maintenance. Transportation Research Record. Washington, DC: Transportation Research Board. 2044(1):3-10. doi: 10.3141/2044-01. Moriarty, K. D., J. Collura, M. Knodler, D. Ni, and K. Heaslip. 2008. Using Simulation Models to Assess the Impacts of Highway Work Zone Strategies: Case Studies along Interstate Highways in Massachusetts and Rhode Island. TRB 2008 Annual Meeting. Washington, DC: Transportation Research Board. CD-ROM submission. Retrieved fromhttp://www.workzonesafety.org/files/documents/database_documents/Publication9955.pd f. Paaswell, R. E., R. F. Baker, and N. M. Rouphail. 2006. Identification of Traffic Control Devices for Mobile and Short Duration Work Operations. FHWA-NJ-2006-006. Accessed March 20, 2011.http://ntl.bts.gov/lib/25000/25000/25088/Final_report-Work_Zones_DevicesUTRC.doc. Pisano, P .A., L. Goodwin, and A. Stern. 2002. Surface Transportation Safety and Operations: The Impacts of Weather within the Context of Climate Change. Weather. pp. 1-20. Retrieved fromhttp://climate.dot.gov/documents/workshop1002/pisano.pdf. Pisano, P. A., L. C. Goodwin, and M. A. Rossetti. 2008. U.S. Highway Crashes in Adverse Road Weather Conditions. Most. pp. 1-15. Retrieved fromhttp://ams.confex.com/ams/pdfpapers/133554.pdf. Qin, X., D. Noyce, C. Lee, and J. Kinar. 2006. Snowstorm Event-Based Crash Analysis. Transportation Research Record. Washington, DC: Transportation Research Board. 1948(1):135-141. doi: 10.3141/1948-15. Shane, J. S., K. C. Strong, and D. Enz. 2009. Construction Project Administration and Management for Mitigating Work Zone Crashes and Fatalities: An Integrated Risk Management Model. Ames, Iowa: Midwest Transportation Consortium. Iowa State University.http://www.intrans.iastate.edu/mtc/researchdetail.cfm?projectID=1216322435 Shi, X. 2010. Winter Road Maintenance: Best Practices, Emerging Challenges, and Research Needs. Journal of Public Works and Infrastructure. 2(4):318-326. Sorenson J., E. Terry, and D. Mathis. 1998. Maintaining the Customer-Driven Highway. Public Roads. 62(3):45. Steele, D. A, and W. R. Vavrik. 2010. Improving the Safety of Mobile Lane Closures. Transportation Research Record. Washington, DC: Transportation Research Board. 2169(1):11-20. doi: 10.3141/2169-02. Sun, D., P. Ravoola, M. A. Faruqi, B. R. Ulman, and N. D. Trout. 2011. Assessment of Need and Feasibility of Truck-Mounted Changeable Message Signs (CMS) for Scheduled and Unscheduled Operations. FHWA/TX-TECHNICAL REPORT #11/0-6167-1.
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Washington S., M. Karlaftis, and F. Mannering. 2010. Statistical and Econometric Methods for Transportation Data Analysis. 2nd Edition. pp. 349.
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APPENDIX A. LIGHTING STUDIES This appendix includes a summary of three major service vehicle lighting studies with relevance to our study for risk mitigation in mobile and maintenance operations. Study 1: Effect of Warning Lamps on Pedestrian Visibility and Driver Behavior University of Michigan, Transportation Research Institute This study examined how warning lighting has an adverse effect on drivers’ ability to see workers outside of their vehicles. The three areas of the study cover nighttime glare from warning lamps, effects on driving performance, and nighttime photometry. The study was done on a closed course track with a mannequin set up near a vehicle that was at a standstill and a panel of warning lights set to various settings, where drivers were asked to identify at exactly what point they were able to see the mannequin. The horizontal passing distance between the mobile car and stationary car was also measured in each trial. The major findings in this study showed that the only major deterrent from the driver’s ability to see the mannequin standing near the parked vehicle was the level of reflective clothing that the mannequin was wearing. Study 2: Recommendations for Service Equipment Warning Lights Texas Department of Transportation (TxDOT) This study was part of a larger research project about maintenance activities. According to TxDOT operation manuals, blue lights are to be used by maintenance vehicles that travel less than 5 mph slower than operating traffic in a travel lane or 30 mph less than operating traffic when not in a traveling lane. Results show people have learned a hierarchy with regards to flashing warning lights. Yellow conveys the least degree of danger, a combination of yellow and blue conveys the second least, a combination of blue and red represents the highest perception of danger to drivers, and red is perceived to represent more danger than any of the other lights individually. People also believe there is less of a need to slow down when yellow warning lights are used compared to other colors. This study also reviewed which types of vehicles drivers associate with different color of warning lights. Yellow lights are associated with the most basic service vehicles, including maintenance and motorist-assistance vehicles, such as tow trucks. People most associated blue and red lights with police and law enforcement vehicles. Red warning lights were most likely to be associated with ambulances, fire trucks, and emergency-response vehicles.
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A set of warning lights was placed on a roadway to monitor the average speed of vehicles as they related to the color of warning lights. The only two lights that were compared in this study were yellow and blue. The color combination of yellow and blue showed the only statistically significant speed difference in this study. The blue or yellow lights alone did not show any significance in speed reduction. This study also explored the effect of warning light colors on brake light activations. The only lighting set-up that did not show a statistically significant increase in brake applications was yellow only. The researchers believed that this portion of the study was the most important and showed the best indicators of how people actually respond to warning lights. They also stated evidence of an incremental benefit to implement a combination of blue and yellow lights rather than yellow alone. Study 3: LED Warning Lights for DOT Vehicles CTC and Associates, Wisconsin Department of Transportation (WisDOT) Studies on the use of LED lighting have come with mixed results from several different applications. Wiring these LED systems, when compared to standard strobe lights, is cheaper. However, the overall startup has higher associated costs. Differing colors have presented cost issues as well. LEDs present far fewer maintenance problems over the long term so, in many cases, LEDs have been less expensive overall. LEDs have been found to have a running life under field conditions of around 100,000 hours and only draw about 10 percent of the amperage of normal incandescent lighting systems. LEDs are able to turn on and off much more quickly so their ability to “punch” signals rather than turning on from a slow glow is better. LEDs will likely be an extremely economic alternative to the systems in use currently. Another advantage of the LED’s ability to turn on faster is the capability for trailing drivers to see a vehicle that is breaking in front of them. According to the study, the extra time saved in signaling presents one extra car length of room for drivers to react at 65 mph. When retrofitting fleets, it is important to consider how many phases it will take to equip all of the vehicles. It can be a problem if too many vehicles are taken out of commission at one time and take away from the day-to-day duties of the fleet. For example, it would be most economical to fit snowplows during the summer when the equipment is not being used.
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APPENDIX B. EXPERT PANEL SUMMARY REPORTS TAC Kick-Off Meeting Moving operations is a common term used for construction activities that involve mobile work zones, such as painting and pavement marking, guardrail replacement, repair of the signage, pavement inspection, structural testing, and so forth. These activities fall under the general heading of operations and maintenance (O/M). The basic objective of this research is to develop an integrated risk modeling approach, which could be used to reduce the frequency and intensity of loss events (property damage, personal injury, fatality, etc.) during highway O/M activities. The first task of the research plan is to identify the current O/M processes used by state, county, and local agencies. To begin this task, a meeting was held at the Institute for Transportation (InTrans) with the expert technical advisory committee (TAC) on December 10, 2010 to identify those current O/M processes. During the panel discussion/brainstorming workshop, identified O/M activities were classified into four broad categories per the activities, environments, and tools/equipment used and the different relationships involved with O/M functions. The potential risk factors involved in the categories that were identified during this meeting include the following: ? ? ? ? ? ? ? ? ? Traffic level/congestion Number of roadway lanes Posted speed limit Inadequate/improper signage Inadequate/improper vehicle lighting and marking Insufficient worker training Proximity of obstructions (equipment) to traveled roadway Weather (condition of road surface, visibility, etc.) Work under traffic (inadequate separation or lack of detours/lane shifts)
Moving operations involve mainly the following four types of work zones: ? ? ? ? Short-term work zones Intermediate work zones Overnight work zones Work zones within 15 ft of the moving traffic
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Current O/M Processes and Practices A detailed, edited report of current O/M processes and practices follows. A. Activity 1. Material testing: The methods generally used for roadway and pavement testing are as follows. Falling-weight deflectometer (FWD) structural testing - A non-destructive test performed to evaluate the strength properties of the pavement and subgrade layers. Information is used in the pavement management system as well as in the pavement design process. The equipment stops in the lane and the loading instrument is lowered to contact the pavement. Ride-quality testing – A non-destructive test conducted with either a 25 ft profilograph or a lightweight inertial profiler to measure the ride quality of a pavement or bridge surface. The profilograph is pushed at about 3 mph. A lightweight profiler operates at 10 to 20 mph. Core drilling – A destructive process used to drill and cut out a pavement core for laboratory analysis. The drill is truck mounted. The truck stops in the lane and the drill is lowered to contact the pavement. Manual condition surveys – A non-destructive process to obtain condition data for a pavement section. The FWD and core drilling operations involve stopping in the lane of travel. Depending on the distance between stops or the length of time stopped, these operations will be either a moving operation or a temporary lane closure. Once the test is taken or the core is drilled, the equipment can move to the shoulder to allow traffic to proceed. Ride-quality testing involves a machine/equipment mounted on a moving vehicle and thus belongs to the moving operations work zone. The testing is continuous and the equipment must stay in the lane and at test speed for the duration of the test section. The condition survey process is done from the shoulder when there is a wide enough shoulder. Staff may have to enter the lane to take measurements, normally at traffic gaps. These testing operations can often block the main roadway and disrupt/slow down the normal flow of the traffic. The risks posed by these types of operations include, but are not limited to: distract the drivers’ attention, force the vehicles to move toward the roadway edge, loss of control, and infringe on sidewalk or bike path.
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2. Bridges and culvert repair and inspection: These types of operations are also moving work-zone operations, as most of the inspection activities are of short duration. These activities also pose risks including, but not limited to, blocks the main roadway, slows down the traffic, distracts the drivers’ attention toward the work zone, forces vehicles to move adjacent to the testing equipment, forces vehicles to move toward the roadway edge, loss of control, and collision with guardrails of the bridges or the culverts. Therefore, these types of inspection activities also pose risk. 3. Mowing: This activity doesn’t typically affect the traffic but would be considered a work zone when it occurs within 15 ft of the roadway. However, while mowing a sloped embankment on the side of a pavement or a roadway, the equipment may block the traffic to some extent and the same risks as mentioned above may occur. 4. Movement of street sweeper: A street sweeper or street cleaner refers to a variety of mobile equipment that cleans streets, usually in an urban area. This type of activity slows down traffic to less than the normal traffic speed and may distract drivers’ attention. 5. Painting: Painting constitutes the major portion of moving O/M activities. About 90 percent of the painting activities belong to the moving operation category. Painting has a big impact on traffic. It is extremely dynamic and depends on several factors. Roadway/pavement painting is of two types: straddling (for centerline painting) and offset (for edge-line painting). The straddling type doesn’t affect the traffic much compared to offset. However, the riskiest situation is the edge-line painting on two-lane two-way traffic roads, because the traffic is moving in the opposite direction of the operation. The most difficult situation arises when the traffic has to be maintained in both lanes. In some situations, the traffic coming from one direction may need to let the traffic from the other direction pass by temporarily when the painting operation blocks a roadway (especially during edge-line painting). 6. Pavement markings: Pavement markings are very important as a guide to drivers and are also included as a moving operation as it involves marking the pavement by blocking the traffic in that zone for a short duration. This also blocks and slows down the traffic and creates similar problems as that of painting. However, in this case, care should be taken about the safety of the unprotected (not inside a vehicle) workers working on the roadways, as sometimes vehicles coming at high speeds may lose control. 7. Crack filling/patch work: Crack filling/patch work is a really “hectic” maintenance operation of the roadways and the roadway may be blocked for up to half a day in the case of a high-volume road. This type of work involves flagger operations, which act as a signal for the moving work zone. In addition, high-strength materials are used here so that the road track becomes usable after a short while. However, workers are responsible for guiding the public to stop and move off to the shoulder and also make them stop until the work is done. In other situations, O/M workers may simply wait for a break in traffic and walk out into the traveled path to fill a crack.
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8. Curb and surface repairs: Curb and surface repairs are usually done by smaller trucks and equipment (e.g., pick-up trucks and even golf-cart-type buggies), which do not have as much protection or visibility when positioned next to moving vehicles. Therefore, curb and surface repairs can become a risky operation in a busy roadway. This type of repair work also blocks the traffic road for a while and thus makes the normal traffic flow slower and may distract drivers. 9. Flagger operations: Flagger operations take place generally on a two-way two-lane highway where the roadway is partially blocked for a moving O/M activity. The portion that is blocked is guarded by two flaggers or signals on either side, which stops the flow of traffic on the lane where work is going on, letting the traffic move on the other lane and, then, the flow is reversed (opposite lane traffic is halted and the disrupted lane traffic is allowed to pass). This is a timed activity and attention is given to the fact that traffic is affected by the O/M activity. 10. Replacing/repairing the signals and signage: Many sign-replacement and repair tasks occur at the side of the road and most times do not disrupt the traffic flow. If the work is on the shoulder, it is safer than in the traveled lane, but workers who are very close to the track (within 15 ft) are at risk. Special precautions are needed so that workers do not mistakenly enter the traveled roadway/street. In some instances, barricades need to be put up to keep the traffic flow from the work-zone. In case of repairing or removal of the signage over the roadway, boom trucks are generally used, which also block the roadway and disrupt the traffic to a great extent. 11. Loading/unloading material for maintenance operations: This is an activity where the trucks may block traffic while unloading/loading material, for maintenance of signals and signage, for instance. If it is a low-volume road, the problem is not as significant compared to a high-volume road. However, the associated risk events are quite dangerous. On a two-lane two-way road, loading/unloading material can block the vision of the vehicle operators. Moreover, the vehicles trying to pass the obstructing truck may move onto the side lane and cross the centerline where vehicles are coming from the opposite direction. Pedestrians, on finding that the sidewalk is blocked, may also try to pass the truck by coming onto the roadway. 12. Shoulder grading: Shoulder grading involves the shaping and stabilizing of unpaved roadway shoulder areas. This maintenance activity can be completed year-round, but is usually programmed between April and November in Iowa. A shoulder-grading crew utilizes about 10 workers on the road, in addition to graders, dump trucks, a belt loader, a roller, and usually a street sweeper. Therefore, this activity has a significant impact on the traffic as it involves several types of equipment that block the roadway and slows down traffic. 13. Repair, maintenance, and installation of guardrails, cable rails, and barrier rails: Guardrails and cable rails may be very close to the traveling lanes, just at the edge of the shoulder, and these rails frequently need repair or replacement when they are hit by a vehicle. Many times, if their damage is projected outside the roadway, they may be replaced or
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repaired without blocking the traffic. But, if the shoulder width is not enough or the damage is projected toward the traveling lane, it becomes a mobile work-zone condition. In these cases, a portion of the road needs to be closed temporarily. In addition, drivers tend to move toward the centerline of the road while passing the short length of the temporary work zone, which can pose risks if it is a two-lane two-way roadway. On the other hand, the repair and maintenance of barrier rails (mainly at the center of the road) and some guardrails and cable rails that are at the center of the road (such as for many bridges) present different work-zone conditions. Here, the risk is more for the safety of the workers rather than the traveling public. If a vehicle loses control and crosses the centerline, bridge deck crews have limited time or routes to escape from that situation, particularly vehicles coming from the opposite direction. 14. Maintenance of sanitary and storm sewer and water main: In this case, the equipment is kept on the shoulder, but if the space is not adequate, some parts of the roadway need to be blocked, which, again becomes a moving work zone. 15. Ditch cleaning: Similar to sanitary and storm sewer and water main maintenance, ditch cleaning is not a high- risk event in most cases, except for potential driver distraction and that traffic may become a little slower if a part of the roadway is blocked. 16. Cleaning storm sewer intakes and structures: This activity is similar to sewer and water main maintenance and ditch cleaning. 17. Survey work: Survey work is a moving operation that often needs to block the roadway for a short while. One of the main problems is that survey work uses minimum work-zone signage, which creates several problems, particularly on two-way highways. In many cases, drivers do not understand what the survey crew is doing. Moreover, vehicles moving at high speeds need time to lower their speeds, for which proper signage should be installed at a certain distance from the work zone. 18. Ingress and egress from construction site: Ingress and egress from the construction site is a risk event created when trucks load and unload materials needed for repairs and maintenance jobs for signals and signage, among others. The trucks need to slow their speed when they ingress the work-zone site and need to separate themselves from the moving traffic. This often creates a problem on high-volume roads as the traffic behind the truck also needs to slow down. Again, the same problem arises at the time of the egress from the work-zone site. The trucks need to come back to the normal traffic flow by entering the right lane and gaining the required speed. This activity also blocks moving traffic to some extent and proper signals need to be given so that accidents and head-on collisions can be avoided. 19. Electric/power system maintenance and street lighting: In many states, the electric/power system is overhead, above the traveled lane, so repair or maintenance of such overhead lines requires the use of boom trucks, which may block the roadway and disrupt the normal traffic
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flow. These activities can also distract driver attention and force drivers to move toward the centerline of the road. Proper attention should also be given to the safety of the crews working in these kinds of work-zones as workers in overhead buckets have little mobility or protection. 20. Snow removal: Generally, snow plows are used to move snow from the roads and streets, but, they may be unobserved by drivers, which can lead to accidents. In addition, removing snow frequently requires end-loaders to back into traveled lanes, especially in urban areas (streets). Because of the unique characteristics of snow removal, it is excluded from this study. B. Environment 1. Nighttime operations: To avoid the high volume of traffic in rush hours, some operations are done at night. But, night operations on bridges are risky for both materials testing and maintenance operations. Coring, painting, some patching work, debris pick-up, and different barrier rail repairs are done at night rather than in the daylight. In all these cases, the major issue is lighting of the work zone. If the work zone is properly illuminated, problems are minimized. But, most of the mobile work zones require portable lights, as many of the working regions may not have proper street lighting. 2. Rutted roadways: Due to weathering effects, the roadway tracks in the traveled lanes can become deteriorated and the middle of the tracks may have potholes. This often affects driver behavior as, to avoid the potholes, drivers try to move toward the edge of the road and may hit signs or guardrails. Sometimes, drivers are forced to move toward the centerline and therefore shift lanes to where vehicles are moving at a different speed (divided four-lane) or vehicles are coming from the opposite direction (two-lane two-way). Unanticipated movements such as these can create risks in mobile work zones. 3. Small towns or schools nearby: If the work zone is near a small town or a school, the work in that area needs to be scheduled according to the timing of the local peak traffic flows. For instance, in the case of a school, the work needs to be stopped near the time when school starts or ends. Roadways cannot be blocked at those peak hours as that causes real inconvenience to the public and also increases the risk factor to a higher degree. 4. Ramps and roadway intersections: If work is at intersections or ramps, proper signals and signage are often not installed for the drivers coming from the other lanes where no work is being performed. Proper attention should be given to the movement of these vehicles (on the intersecting or merging roads/streets), so those motorists know of the work zone ahead. Without such configurations, entrance to the work zone cannot be controlled. Signage and warnings are needed on both sides of the ramps. Again, all signage should be pertaining to the current work situation and thus needs to be updated according to the progress of the work.
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5. Pavement markings: This type of work is done generally in the morning hours to avoid disruption of traffic, especially at intersections. 6. Roads in hilly areas: In hilly areas, sight distance is problematic. In any hilly work-zone area, flaggers may be employed ahead of stoplights to make sure information about the work zone is communicated to the public at the appropriate time and distance and to make sure convoys stay together. 7. Peak traffic hours: Work should be scheduled in moving work zones according to the traffic hours. Generally, in peak traffic hours on high-volume roads, the work is stopped for a while and is again resumed after the peak hours. 8. Variable travel pattern: In some areas, different institutions (like the Iowa DOT, University, and Animal Disease Lab in Ames, Iowa). create different and variable peak travel times. Therefore, some decisions on moving operations require local knowledge or input. 9. Work near railway crossings: Work near railway crossings should be done very carefully and also needs to be stopped when a train is approaching. Therefore, this work should be coordinated as much as possible with train schedules. 10. Responding to emergency vehicles: In these cases, the work is brought to a temporary halt and the emergency vehicle is allowed to pass by. 11. Unforeseen weather conditions: The weather conditions in Iowa can be quite variable and difficult to predict, especially in the last three years. Flexibility to move to another site for O/M work is needed if the weather is bad in the region where work was originally planned. For instance, if a large area is experiencing heavy rain or dense fog, the scheduled operation needs to be shifted to a different area. 12. Fog and mist: Fog or mist is a temporary weather situation that affects visibility for a short time (usually early mornings) and/or in a small area (river valleys). In this situation, either special signals are used to warn drivers of a mobile work zone nearby or, if the situation worsens, work is brought to a temporary halt. 13. Different rules in shared jurisdictions: Different rules can apply when work moves “across the street” in a shared jurisdiction, which mainly includes city streets, DOT routes, and institutional routes (such as within Iowa State University). This sometimes creates confusion among drivers, contractors, utility companies, etc. and may cause inconvenience (permits, notifications, coordination, etc.) to the working crews in the different mobile work zones. 14. Special events: Different special local events such as parades, races, and fairs are carried on in local cities and towns, which may block the road for a while. These also stop the work in the O/M work zone for a while to give space for the events to take place.
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C. Equipment 1. Falling-weight deflectometer: This type of equipment is used to test the strength properties of the pavement and subgrade. This equipment is mounted on a moving vehicle, which stops in the lane to test at different locations. Because it is stop-and-go, it hinders the normal traffic flow to some extent. 2. Straddling painters: These are mobile painting machines used to paint the centerline of roads. Usually, they do not block traffic but will slow traffic flow in both directions. 3. Maintainers on gravel roads: No signage is used during this operation. Most work is on low-volume roads with local traffic only that is knowledgeable of the operation. 4. Cold-mix patchwork: Generally, when cold mix is put in a hole on the roadway, traffic is not affected and no signage is used for this activity. 5. Friction testing: This machine can disrupt traffic because of the water that is applied to the roadway surface during the three-second test at 40 mph. 6. Media trucks: Although the work is for a short duration, these vehicles and their operators frequently lack safety protocols while working. They may block the road for more than two hours and often do not use any proper signage, which can disrupt the movement of traffic. 7. Trucks carrying rock/aggregate: Many times, rocks and other aggregate may fall on the roadway while being hauled, sometimes cracking the windshields of the following vehicles. Proper signage should be used and precaution should be taken. 8. Boom trucks: These trucks are mounted with long booms, which are used to maintain and repair signage and signboards across the road lanes and also help to repair the overhead electric lines at times. 9. Pick-up trucks: This is a light-weight motor vehicle used to carry light material, tools, and equipment from one place to another or during inspections. 10. Street sweepers: A street sweeper or street cleaner refers to a machine that cleans streets, usually in an urban area. 11. Jet vac: This equipment is used for cleaning the leaves out of storm or sanitary intakes and structures. 12. Paint carts (hauled on trailers): Paint carts are usually used when painting roads and pavements in urban areas (e.g., turn arrows and crosswalks).
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13. Proper signage: Proper signage at different types of moving work zones is a necessity in preventing accidents and warning drivers in advance about the work zone. The signage should be changed as the work progresses so that current information can be conveyed to the public. 14. Fluorescent diamond signs: These types of signs should be used at the back of the vehicles and equipment to notify the drivers coming from behind that a moving work zone is ahead. 15. Use of lights/blinkers: Several types of lights and blinkers are used in the mobile O/M work zone with little standardization. 16. Fluorescent borders: In some mobile work zones where work is conducted mainly at night or equipment is stored overnight, fluorescent-colored indicators form borders on signs to signal that a mobile work zone is ahead. 17. Speed limit fines: Fines for mobile operations generally do not exist as they do for other construction activities, so drivers may not be as aware or as careful in these types of operations. D. Relationships 1. Coordination with municipalities: Many times due to lack of communication, local events have an impact on O/M activities. This is probably a bigger problem for centralized state activities than for local (e.g., county) activities. 2. Advantage of closed roads: For many types of O/M activities, preference of work should be given to roads that are temporarily closed. However, due to lack of coordination and information, static and mobile operations often run into each other. 3. Coordination between state and local agencies: Sometimes due to lack of information, state and local agencies may come to work at the same place at the same time, which may create a problem. 4. Worker safety and training programs: Younger and temporary O/M workers are not given enough training, which may lead to inefficient work and an unsafe work zone. 5. Train the trainers: This philosophy is used to train all the employees of the organization to the extent required only for performing their particular work. Supervisors are given training, which they in return deliver to the employees in their team. If any additional problems occur, it is generally escalated to the supervisor. 6. Control of right-of-way (ROW): Frequently, ROW managers are not aware of O/M activities occurring in the ROW. While the DOT tries to coordinate ROW permits, they don’t always get a copy of the final permit. In some local and institutional situations,
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communication or coordination is lacking when control of the ROW changes. Private utilities and contractors making taps or upgrades in streets or ROWs should get a new ROW permit form, which contains a requirement for traffic-control planning, but this doesn’t always happen. 7. Third-party interaction: There is subcontracted maintenance and repair work on some major utility repairs, especially directional drilling for electrical conduit. There are also O/M activities on shared jurisdiction roads. Neighborhood groups often do not communicate upcoming activities. O/M also tries to coordinate with law enforcement on issues such as missing signs or placement of stop signs. O/M also needs to coordinate with railroads and utilities on maintenance of rail crossings and utilities under the railroad.
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APPENDIX C. EXPERT INTERVIEWS This appendix includes information from three in-depth follow-up interviews with experts. Follow-Up Interview with Bob Younie, State Maintenance Engineer Discussions with Bob Younie mostly included an overview of the chain of command in the Iowa DOT and what can be done internally to help mitigate risk. In more recent years, the Iowa DOT has decided to flatten their chain of command in an attempt to cut back on overhead expenses. The overhead costs have been diminished, but so have other portions of operations that maybe should not have been. For example, the total number of man hours spent in training in 2000 was roughly 103,000 hours, compared to 2010, when roughly 44,000 man hours were allocated to training, which includes safety training. Included in this interview summary are organizational charts for Iowa DOT staff and their positions in the Highway Division and the District 2 Highway Division for reference on how the organization is currently set up (Figures C.1 and C.2). One of the main points of concern that Bob brought up was the lack of emphasis on coordination of training and safety programs. Bob expressed that he was more concerned with managerial operations that addressed safety and risk mitigation than with dangerous working conditions. In short, the problems in executing safety procedures come from poor training strategies and that, if strategies were adjusted, the outside (worksite) risk factors would become less of a problem. Because of the flattening of operations, more work has been assigned to division and shop managers, which means less time in the work week for managers to hold training sessions. At one point in time, most garages were managed by a single supervisor. Today, the trend is that an individual manager now is responsible for two to four maintenance garages, cutting their ability to supervise all operations or O/M crews directly and effectively. Along with not being able to hold as many training sessions, shop managers, as well as division managers, are not available to hold “Job Box Talks” or to have daily safety reminders. Because of the increased span of control (two to four garages instead of one), managers also find it difficult to schedule face-to-face meetings with O/M field crews to discuss things that are unique to a certain job or area they are working on for that day. These daily reminders are often the best line of defense when it comes to safety for an individual operator, because they are hearing from their direct supervisors and can know that their safety is in their supervisor’s best interest. Shop managers likely have the most experience when it comes to jobsite safety, especially when it comes to a regional or local problem area.
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Figure C.1. December 2010 Iowa DOT Highway Division organizational chart
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Figure C.2. December 2010 Iowa DOT District 2 Highway Division organizational chart 85
Another point of emphasis that Bob brought up is that there may not be enough Best Practices meetings held within divisions. If a local garage or division finds that a certain process works better than another does, it does not seem to filter out to other garages as quickly as it should. It was suggested that shop managers be encouraged to meet with division managers and other shop managers to discuss best practices that are discovered in the field, especially when it comes to safety. It was also encouraged that division managers call meetings periodically to encourage this type of information sharing. In further discussion about safety training, Bob was not convinced that adequate training was being taught on all levels, especially at the supervisory level. He felt the DOT currently is not doing enough to prepare its garage supervisors to manage safety in their local regions and, in turn, their operators are not receiving a well-rounded safety training background. The amount of formal training does not seem to be translating into peer training or the ability for one operator or laborer to identify a safety problem and show another why they are working unsafely. Interview with Mark Black, Iowa DOT District 2 Engineer After review of the Maintenance Instructional Memorandum (IM) there were a few suggestions that Mark Black discussed maybe should be changed on a broad level that their garage has already implemented. On top of the IM review, Mark also suggested that the Traffic Control Manual be reviewed, as well as the Flagger’s Handbook. (The researcher’s later discovered this Traffic Control Manual is a reference that the district put together and updates each April and October to coincide with revisions to the Standard Road Plans, which are available athttp://www.iowadot.gov/erl/index.html.) The Traffic Control (TC) Manual at one point in time was included in the Maintenance IM as an appendix but grew over time to include a wide variety of differing work-zone set-ups. At some point, recently, the traffic control diagrams (labeled Traffic Control Standard Road Plans – TC Series online) were removed and compiled into a separate standalone binder. Following are the issues that Mark Black would like us to consider in our study. At the point in time when the TC Manual became a separate publication, the references from the Maintenance IM to the diagrams in the TC Manual never changed. When these diagrams were included as references in the in the Maintenance IM they were annotated as RC diagrams (RC-1, RC-3). The RC designations are no longer used, but are still referenced in some places. Now that traffic control diagrams are in a separate TC Manual, the titles of the diagrams have changed (e.g., TC-1). This makes referencing diagrams from the Maintenance IM difficult. Another problem with the references to the traffic control diagrams is that the Maintenance IM still refers to an appendix that once included these diagrams, indicating that a section of the Maintenance IM is missing, rather than recognizing that there is now a separate manual for Traffic Control. This causes problems for crew foremen, because they are confused as to which
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diagram to use. The result is that neither the TC Manual nor the Maintenance IM is used as efficiently and thoroughly as intended. The second problem that should be considered is the location of diagram-specific notes in the TC Manual and how they should be referenced. As it stands now, the diagram-specific notes are still located in the Maintenance IM , indicating they did not travel with the diagrams, as they should have when the TC Manual became a separate publication. The required cross-referencing between the Maintenance IM and the TC Manual was never completed. Mark indicated that the notes included in the diagrams were just as important as the diagrams themselves, because they have control standards that vary from job to job. For example, for a certain working activity, if the work zone is less than a quarter of a mile, certain safety measures are used and, if the work zone is longer than a quarter of a mile, a different set of standards are used. Without reading the notes that are associated with a traffic control diagram, a crew foreman may miss these operational standards completely. Mark indicated that not reading through these notes for specific traffic control setups could be extremely hazardous and hinder the ability to protect the workers of the operation properly. An example of a traffic control diagram is included as Figure C.3. This would be the only reference for a crew foreman. The diagram has no indication of the supplemental notes that should be evaluated in this work zone. Also note the title of TC-202 in the bottom right corner, which was not always the standard title. The traffic control diagrams (Standard Road Plans – TC Series) can be found athttp://www.iowadot.gov/design/stdplne_tc.htm.
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Figure C.3. Sample traffic control diagram for a shoulder closure
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The third topic discussed by Mark is the use of truck-mounted attenuators (Figure C.4).
Figure C.4. Truck-mounted traffic attenuator Mark indicated that these types of vehicles in a mobile operation are the first piece of equipment that actually is in the lane of traffic. He indicated there are inherent problems when using this equipment. The problem with this type of equipment is that it is designed to push traffic over to another lane, but it is not designed to handle the impact of being struck by a moving vehicle. The single biggest threat, Mark said, was that vehicles such as semi-trucks and trailers did not have the ability to stop and have caused catastrophic damages including loss of life and extreme property damage. The incidents Mark discussed also showed that references to the diagramspecific notes could have been reviewed more thoroughly as conditions such as traffic volume had changed over the course of several years of work. Interview with Jeff Koudelka, Vice President of Iowa Plains Signing, Inc. Iowa Plains Signing does many different types of work involving mobile operations including line striping and installing temporary barrier rails and is often accountable in other mobile operations for many other safety measures. About 95 to 97 percent of their work is subcontract work. The primary concern that Jeff expressed with relation to mobile operations is the ability to attract driver attention and drivers’ abilities to identify and respect the mobile work zone. He feels driver distraction causes many more incidents than any failure of their own to adhere to safety standards. To help curb this problem of drivers’ not paying attention to changing roadway conditions, strobe-type warning lights have been installed on every vehicle used in their mobile fleets. This is not a DOT safety standard; rather, it is a practice implemented by Iowa Plains Signing that goes above and beyond the typical standard. Another point of concern was the inability to keep vehicles from changing lanes between vehicles in the operation rather than passing all of the vehicles in the line at once (Figure C.5).
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Figure C.5. Desired versus dangerous passing path The dangerous passing path around and between the O/M vehicles poses two major issues in that the contractor is no longer able to control the entire work zone that the passenger vehicles are traveling through and presents two points where drivers potentially cut off maintenance vehicles too closely when passing rather than one. Passenger vehicles often do not allow enough space when returning to the traveling lane between themselves and the maintenance vehicle. This poses a major threat to persons who are on equipment that does not enclose the operator. A source of this danger often comes from too many maintenance vehicles in a fleet that is operating on a two lane-two way highway. In addition, the Iowa DOT Traffic Control standards do not seem to take into account that fewer vehicles are better for two-lane work, whereas more vehicles are better for multilane and interstate highway work. The third point of emphasis discussed in this conversation was the clarity of diagrams in the traffic control diagram and the inability to go above and beyond the standards shown. In several of the diagrams (such as TC-431) graphics of vehicles to be used in the fleet but near them is an indicator that the piece of equipment is optional. Jeff felt that if it is included in the road standard, the piece of equipment should not be optional and should always be included. Jeff stated that Iowa Plains Signing never allows a piece of equipment to be optional in an operation if it is shown as so on the DOT Traffic Control Standard. Also, oftentimes the vehicles that are depicted in the diagrams do not accurately show the realistic footprint of a piece of equipment. For example a rumble-strip grinder may be shown to be working outside of the traveling lane on the diagram but, in reality, the grinder may be sitting a few feet into the lane or even entirely in the lane of travel.
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The second part of this concern is that because Iowa DOT standards are very specific in how they should be implemented (number of signs, number of trucks), contractors feel they cannot go above and beyond the standards without being liable for damages outside of their work zone. Therefore, standards often constrict the contractor to perform to a standard that does not allow for additional safety measures. Because of all the past litigation Iowa Plains Signing has faced for not adhering strictly to the Traffic Control Standards over seemingly meaningless regulations, they are not willing to provide additional signage and other safety equipment. The last main topic of discussion was the lack of willingness to accept new safety products and implement them in Iowa DOT standards. One item that was specifically talked about is temporary rumble strips (Figure C.6).
Figure C.6. Temporary rumble strips Temporary rumble strips have the ability to grab the attention of drivers and alert them to the potential hazardous situations ahead and can be included in operations that require temporary set up in a specific area. Finally, some innovative items have been adopted in the Iowa DOT standards as recently as 2011. The latest equipment being used in traffic control are automated signal lights, which replace standard flagging controls. These signal lights allow for two fewer laborers to be outside of a vehicle and exposed to moving traffic.
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doc_686693457.pdf
Risk mitigation occurs after the risk assessment phase is complete. Risk mitigation encompasses the prioritization, evaluation, and implementation of appropriate security controls identified during the risk assessment phase.
Risk Mitigation Strategies for Operations and Maintenance Activities
Final Report October 2011
Sponsored by Iowa Highway Research Board (IHRB Project TR-627) Iowa Department of Transportation Midwest Transportation Consortium (InTrans Project 10-389)
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Technical Report Documentation Page 1. Report No. IHRB Project TR-627 4. Title and Subtitle Risk Mitigation Strategies for Operations and Maintenance Activities 5. Report Date October 2011 6. Performing Organization Code 7. Author(s) Kelly C. Strong and Jennifer S. Shane 9. Performing Organization Name and Address Institute for Transportation Iowa State University 2711 South Loop Drive, Suite 4700 Ames, IA 50010-8664 12. Sponsoring Organization Name and Address Iowa Highway Research Board Midwest Transportation Consortium Iowa Department of Transportation Institute for Transportation 800 Lincoln Way 2711 South Loop Drive, Suite 4700 Ames, IA 50010 Ames, IA 50010-8664 15. Supplementary Notes Visit www.intrans.iastate.edu for a color pdf of this and other research reports. 16. Abstract The objective of this research was to investigate the application of integrated risk modeling to operations and maintenance activities, specifically moving operations, such as pavement testing, pavement marking, painting, snow removal, shoulder work, mowing, and so forth. The ultimate goal is to reduce the frequency and intensity of loss events (property damage, personal injury, and fatality) during operations and maintenance activities. 8. Performing Organization Report No. InTrans Project 10-389 10. Work Unit No. (TRAIS) 11. Contract or Grant No. 2. Government Accession No. 3. Recipient’s Catalog No.
13. Type of Report and Period Covered Final Report 14. Sponsoring Agency Code
17. Key Words highway maintenance activities—operations and maintenance—risk mitigation— roadwork risk modeling—traffic control—work-zone safety 19. Security Classification (of this report) Unclassified. Form DOT F 1700.7 (8-72) 20. Security Classification (of this page) Unclassified.
18. Distribution Statement No restrictions. 21. No. of Pages 108 22. Price NA Reproduction of completed page authorized
RISK MITIGATION STRATEGIES FOR OPERATIONS AND MAINTENANCE ACTIVITIES
Final Report October 2011 Principal Investigator Kelly C. Strong, Associate Professor Department of Civil, Construction, and Environmental Engineering Iowa State University Co-Principal Investigator Jennifer S. Shane, Assistant Professor Department of Civil, Construction, and Environmental Engineering Director of Construction Management and Technology (CMAT) Iowa State University Research Assistants Sayanti Mukhpadhay and Jay Mathes Authors Kelly C. Strong and Jennifer S. Shane Sponsored by the Iowa Highway Research Board (IHRB Project TR-627) and the Midwest Transportation Consortium Preparation of this report was financed in part through funds provided by the Iowa Department of Transportation through its research management agreement with the Institute for Transportation (InTrans Project 10-389) A report from Institute for Transportation Iowa State University 2711 South Loop Drive, Suite 4700 Ames, IA 50010-8664 Phone: 515-294-4015 Fax: 515-294-0467 www.intrans.iastate.edu
TABLE OF CONTENTS ACKNOWLEDGMENTS ............................................................................................................. ix EXECUTIVE SUMMARY ........................................................................................................... xi Problem Statement ............................................................................................................. xi Objective ............................................................................................................................ xi Research Description ......................................................................................................... xi Key Findings .................................................................................................................... xiii Research Limitations ....................................................................................................... xiv Implementation Readiness .................................................................................................xv Implementation Benefits ....................................................................................................xv INTRODUCTION ...........................................................................................................................1 Problem Statement ...............................................................................................................1 Objectives ............................................................................................................................1 LITERATURE REVIEW ................................................................................................................3 Weather/Environment ..........................................................................................................3 Mobile and Short-Duration Operations/Maintenance Activities and Equipment ................6 Literature Review Conclusions ..........................................................................................18 RESEARCH METHODOLOGY...................................................................................................19 Identification of Current O/M processes through Expert Input .........................................19 Literature Review...............................................................................................................19 Analysis of the Crash Data ................................................................................................20 Validation Survey ..............................................................................................................23 Identification of Mitigation Strategies ...............................................................................23 DATA ANALYSIS ........................................................................................................................24 Crash Database Analysis Results .......................................................................................24 Validation Survey Data Analysis Results ..........................................................................40 Development of the Integrated Risk Management Model .................................................59 DISCUSSION OF KEY FINDINGS .............................................................................................62 Crash Data Analysis ...........................................................................................................62 Validation Survey Data Analysis .......................................................................................64 Identification of Risk Mitigation Strategies .......................................................................66 Research Limitations .........................................................................................................67 Implementation Readiness .................................................................................................67 Implementation Benefits ....................................................................................................68 REFERENCES ..............................................................................................................................69 APPENDIX A. LIGHTING STUDIES .........................................................................................71 Study 1: Effect of Warning Lamps on Pedestrian Visibility and Driver Behavior ...........71 Study 2: Recommendations for Service Equipment Warning Lights ................................71 Study 3: LED Warning Lights for DOT Vehicles .............................................................72 v
APPENDIX B. EXPERT PANEL SUMMARY REPORTS .........................................................73 TAC Kick-Off Meeting......................................................................................................73 Current O/M Processes and Practices ................................................................................74 APPENDIX C. EXPERT INTERVIEWS......................................................................................83 Follow-Up Interview with Bob Younie, State Maintenance Engineer ..............................83 Interview with Mark Black, Iowa DOT District 2 Engineer .............................................86 Interview with Jeff Koudelka, Vice President of Iowa Plains Signing, Inc. .....................89
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LIST OF FIGURES Figure 1. The Balsi Beam being rotated from side to side.............................................................12 Figure 2. Dancing diamonds (lights) .............................................................................................13 Figure 3. Flagger stopping traffic (left) and portable temporary rumble strips being field tested near Perry, Kansas (right)................................................................................13 Figure 4. Cone shooter ...................................................................................................................14 Figure 5. Automated pavement crack sealer ..................................................................................15 Figure 6. Robotic safety barrel (RSB) ...........................................................................................15 Figure 7. Truck-mounted changeable message signs (event example, left, and lane-blocked example, right) ...................................................................................................................16 Figure 8. Percentage distribution of statewide work-zone crashes according to severity over 10 years (2001–2010) ........................................................................................................25 Figure 9. Statewide work-zone crash severity distribution—total crashes (2001–2010) ..............25 Figure 10. Distribution of the weighted average for the probabilities of the factors for the occurrence of the different types of crashes ......................................................................35 Figure 11. Distribution of the percentage frequency of the factors (crash database) present in all crashes involving intermittent and moving work zones and work on the shoulders and median .........................................................................................................38 Figure 12. Distribution of the severity levels of the factors (crash database) present in all crashes involving intermittent and moving work zones and work on the shoulders and median .........................................................................................................................50 Figure 13. Distribution of the percentage frequency of the factors (crash database) present in all crashes involving intermittent and moving work zones and work on the shoulders and median .........................................................................................................54 Figure 14. Risk assessment matrix.................................................................................................60 Figure C.1. December 2010 Iowa DOT Highway Division organizational chart .........................84 Figure C.2. December 2010 Iowa DOT District 2 Highway Division organizational chart .........85 Figure C.3. Sample traffic control diagram for a shoulder closure ...............................................88 Figure C.4. Truck-mounted traffic attenuator ................................................................................89 Figure C.5. Desired versus dangerous passing path ......................................................................90 Figure C.6. Temporary rumble strips .............................................................................................91
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LIST OF TABLES Table 1a. Effective technologies/safety devices for mobile operations ...........................................9 Table 1b. Effective technologies/safety devices for mobile operations ........................................10 Table 2. Techniques adopted for safer mobile work zones ...........................................................11 Table 3. Criteria satisfied by selected work-zone device/equipment ............................................11 Table 4. Variables queried from the Iowa crash database .............................................................20 Table 5. Iowa statewide work-zone crash statistics .......................................................................24 Table 6. Descriptive statistics and significance of the indicator variables created or used in the model ............................................................................................................................27 Table 7. Variable description and results .......................................................................................30 Table 8. Marginal effects of the factors along with their severities...............................................33 Table 9. Ranking of the factors according to severity ...................................................................36 Table 10. Frequency distribution of the factors .............................................................................37 Table 11. Ranking of significant factors according to their frequency of occurrence ...................39 Table 12. Risk values of the significant factors .............................................................................40 Table 13. Severity levels of the factor ...........................................................................................41 Table 14. Frequency distribution of the factors .............................................................................45 Table 15. Ranking of the factors according to severity .................................................................51 Table 16. Ranking of the factors according to frequency ..............................................................55 Table 17. Ranking of the factors according to risk assessment value ...........................................57
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ACKNOWLEDGMENTS The authors would like to thank the Iowa Highway Research Board (IHRB), the Iowa Department of Transportation (DOT), and the Midwest Transportation Consortium (MTC) for their financial support of this project, and the Institute of Transportation (InTrans) for administrative and publication support. In addition, the insights and guidance of the following individuals were extremely valuable: Bob Younie – Iowa DOT project liaison Technical Advisory Committee: ? ? ? ? ? ? ? ? Mark Black – Iowa DOT Highway Division District 2 Lynn Deaton – Iowa DOT Paint Crew District 1 Kevin Jones – Iowa DOT Materials Inspection Staff Robert Kieffer, Boone County Secondary Road Department Engineering Jeff Koudelka – Iowa Plains Signing, Inc. Dan Sprengeler – Iowa DOT Office of Traffic and Safety Brent Terry – Iowa DOT Materials Inspection Staff Tracy Warner – City of Ames Municipal Engineering
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EXECUTIVE SUMMARY Problem Statement Previous research on construction work-zone safety found that moving operations represent the highest-risk activity when considering both frequency of occurrence and crash severity (Shane et al. 2009). The research further determined that using an integrated risk model that assesses risk over the project life cycle could mitigate the risk of moving operations (among others) during the construction phase. Hence, this research examines how an integrated risk-modeling approach could be used to reduce the frequency and intensity of loss events (property damage, personal injury, fatality) during highway operations and maintenance (O/M) activities. Objective The objective of this research is to investigate the application of integrated risk modeling to O/M activities, specifically moving operations such as pavement and structures testing, pavement marking, painting, shoulder work, mowing, and so forth. Research Description The methodologies that were adopted in this research are as follows: ? ? ? ? ? Identification of current O/M processes through expert input Literature review Analysis of crash data Validation survey Identification of mitigation strategies
Identification of Current O/M processes through Expert Input The research started with an expert panel session/brainstorming workshop with the technical advisory committee (TAC) aimed at mapping the O/M process as currently utilized by state, county, and local agencies. The objective was to categorize the activities, environments, tools/equipment, and relationships involved with different O/M functions. This session was followed up by in-depth interviews with three members of the expert panel. Literature Review The researchers performed an extensive literature search compiled a preliminary list of risk factors and loss events during O/M activities. The search mainly included results from academic
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journals, trade publications, transportation research technical reports, and state departments of transportation (DOT) web sites. The literature review reveals several studies on the impacts of weather on the roadways and, hence, its effects on work-zone safety, along with specific research on the interaction of traffic and O/M and mobile work-zone-related safety. However, these studies did not specifically address risk assessment and mitigation strategies for the O/M activities on highways. The literature search also gave insight into how the identified factors play a role in mobile workzone crashes, specifically work zones that involve O/M activities on highways. Analysis of Crash Data The analysis of the crash database provided by the Iowa DOT played a very important role in the development of the Integrated Risk Management Model. To obtain information about the relevant crashes, a query was created to gather data for all severity level of crashes from 2001 through 2010 that involved two types of work zones: intermittent or moving work and work on shoulder or median. The suitable variables in the crash database that were able to explain the effect of the previouslyidentified factors (activities, environment, tools/equipment, and relationships) were queried to analyze their effect on crash severities and the frequency with which they occur within the database. The Integrated Risk Management Model consists of two parts: factors contributing to the severity of the crash and the frequency of the factors involved in the crashes. In this research study, the significance of the factors contributing to the severity of the crash was assessed by developing a statistical model and the frequency of those factors that were found to be significant in the model was assessed through descriptive statistics of the crash database. The researchers examined weather (environment), equipment, activities, and related factors to develop a risk severity matrix to indicate the relative severity of each factor on a Likert scale of 1 to 5. By performing an analysis of the crash database, the researchers generated a model (and refined it) to show the relationships between the various factors and the severity and frequency of crashes in mobile work zones. Validation Survey Data Analysis Results The loss events identified in the literature review and crash data analysis were validated in a short survey that was administered to state, county, and local O/M personnel, as well as to traffic safety professionals in the private sector, including both office and field personnel. The survey assisted the research team in ranking loss events in order of risk (frequency and severity). The survey questions included the O/M activities identified from the expert panel session. The participants were asked to rank those activities from their experience according to their severity
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and likelihood of occurrence (frequency), both of which were measured with a Likert scale rank value from 0 to 5. The number of responses obtained was 24. Because of the small sample size, no statistical tests were performed with the survey results. These results were used only to validate the results obtained through the statistical analysis of the crash database. Identification of Mitigation Strategies After identifying potential risk factors, establishing proximate causes, and estimating frequency and severity, the research team identified risk mitigation strategies that could be used to reduce the frequency and/or severity of losses during O/M activities. The potential mitigation strategies were identified after a meeting with the TAC members. Key Findings After identifying potential risk factors and evaluating loss severity, the research team identified the following risk mitigation strategies that can be used within integrated teams to reduce the frequency and/or severity of losses during O/M activities. 1. Revise and integrate the Iowa DOT Instructional Memorandums (IM), Traffic and Safety Manual, and Standard Road Plans – TC Series (traffic control diagrams) and related notes to provide clear guidance on placement of traffic control measures for mobile work zones. 2. Consider expanding traffic-control options to include proven technologies such as the Balsi Beam, portable rumble strips, blue strobe lights, and other innovations. Traffic-control specifications and associated allocation of risk between contractors and state/local agencies would also need to be revised to encourage adoption of new traffic-control measures. This is an area where a follow-up study would prove beneficial. 3. Investigate new delivery technologies (such as Skype, webinars, and remote conferencing) to allow for improved training within the flattened structure of the Iowa DOT. The training should include both formal programs for centralized functions and informal weekly programs for supervisory personnel to discuss issues with field crews. The Local Technical Assistance Program (LTAP) at the Institute for Transportation (InTrans) may be of assistance in developing such a safety-training program. The safety-training program will be particularly helpful for new and temporary employees working in mobile operations. 4. Written manuals and training programs should focus on the importance of worker and equipment visibility and advance warning systems, especially in high-speed environments (interstates and US highways) and those where drivers may be distracted more easily by pedestrians, traffic signals, bicyclists, etc., such as municipal streets.
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5. Schedule Best Practices meetings regularly within divisions. Encourage shop management to meet with division managers and other shop managers to discuss best practices that are discovered in the field, especially when it comes to safety. Division managers should also hold meetings periodically to encourage this type of information sharing. The alternative delivery technologies mentioned above may also be helpful in disseminating best practices. 6. Certain environments should be reviewed to ensure that the minimum number of workers and vehicles are used in the traffic-control system. Specifically, two lane two-way highways, work at railroads and other utility sites, overhead work, and work on bridges are likely highrisk environments where additional vehicles and workers increase the risk of crashes. The value of impact attenuators should be researched to determine the safety benefits of such equipment. The analysis of the crash database did not find any reports of impact attenuators associated with mobile work-zone crashes. 7. Policies and safety training programs should emphasize the need for locating traffic controls at the appropriate distance from the work site to allow for driver reactions, and traffic controls should be moved at the same pace as the mobile operations whenever possible. The research report includes a comprehensive discussion of findings beyond what’s included here. Research Limitations The limitations of this research study are as follows. ? Not all of the factors/hazards that were studied in this research could be described by the crash database variables queried. Representative variables were selected and analyzed from the crash database, which indirectly explained the effect of the required variables/factors/hazards. The data entered on the responding officer’s report does not always match the variable of interest. The crash data were drawn from the Iowa crash database, but the survey and literature review was national in scope. This made the research study somewhat biased. To get a good sample size, crash data from the last 10 years (2001 through 2010) were analyzed. This may have included information about several crashes that occurred after changes in work-zone signage practices and other infrastructure development. The response rate for the validation survey was low. Because of the sample size, no statistical analysis could be performed.
? ?
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Implementation Readiness The possible mitigation strategies developed as a result of this research are not field-tested, as it was out of the scope of this research project. If further research on the implementation ideas is needed, a separate research study can be conducted focusing on the implementation of the riskmitigation techniques found as a result of this study. Testing may include evaluation of the riskmitigation strategies in simulators or actual field situations to determine effectiveness. Implementation Benefits The research findings are intended to provide a process map or guidebook outline for use by the Iowa DOT, Iowa county engineers, and municipal transportation agencies to assess the risk potential of various O/M activities and develop team-based risk-mitigation strategies. The primary benefits of this research are the reduced risk of injury, fatality, and property damage for O/M and the traveling public. The research results can be implemented by the Iowa DOT staff, county engineers, municipal transportation directors, and any other transportation professionals responsible for O/M activities, including field personnel. The results can also be used as a standard process for identifying highest-risk O/M activities and developing mitigation strategies to reduce those risks. However, it should be noted that the riskmitigation processes developed and envisioned in this research are highly inclusive, involving state, local, and regional professionals from both field and office positions. Intuitively, any process that decreases risk should improve worker safety, lower agency costs, improve service to the traveling public, and lead to more-efficient procedures over the long-term, although these specific performance benefits are not assessed directly as part of this research project.
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INTRODUCTION Problem Statement Previous research on construction work-zone safety found that moving operations represent the highest risk activity when both frequency of occurrence and severity of loss are considered (Shane et al. 2009). The research further determined that using an integrated risk model that assesses risk over the project life cycle could mitigate the risk of moving operations (among others) during the construction phase. Although designed specifically to examine risk and safety for work-zone applications, the research indicated that construction activities that involve moving operations (e.g., painting, guardrail placement) represented the highest risk. This finding suggests that the risk-modeling process could be applied beneficially to operations and maintenance (O/M) functions outside of static construction work-zone applications. Hence, this research examines how an integrated risk-modeling approach could be used to reduce the frequency and intensity of loss events (property damage, personal injury, fatality) during highway O/M activities. Objectives The objective of this research is to investigate the application of integrated risk modeling to O/M activities, specifically moving operations such as pavement and structures testing, pavement marking, painting, shoulder work, mowing, and so forth. The ultimate goal is to reduce frequency and severity of loss events (property damage, personal injury, and fatality) during O/M activities. Potential risk factors to explore included the following issues: ? ? ? ? ? ? ? ? ? ? ? Traffic level/congestion Number of roadway lanes Posted speed limit Inadequate/improper signage Inadequate/improper vehicle lighting and marking Insufficient worker training Proximity of obstructions (equipment) to traveled roadway Physical limitations of crash attenuators Limitations of equipment due to the specialized nature of the fleet Weather (condition of road surface, visibility, etc.) Work under traffic (inadequate separation or lack of detours/lane shifts)
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After identifying potential risk factors and evaluating loss severity, the research team identified risk mitigation strategies that can be used within integrated teams to reduce the frequency and/or severity of losses during O/M activities.
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LITERATURE REVIEW The literature review is intended to identify the current and common practices for safe and efficient highway O/M that have been adopted by different state departments of transportation (DOTs) and other agencies throughout the world. The review also attempted to find out some of the factors that increase the likelihood of vehicle crashes during any type of mobile operations on highways, like testing, painting, repairing and replacement of guardrails, etc., and how the different agencies take precautionary measures to mitigate the chance of crashes due to these factors. However, it has been found that most of the research has been done on the impacts of weather and different climatic changes on highways and other surface transportation systems with only a few studies focusing on the identification of traffic control devices and safety for mobile and short-duration work zones. Much less focus has been given to a comprehensive examination of risk factors and mitigation strategies for mobile operations, which is the focus of this research project. Weather/Environment The National Research Council estimated that drivers endure more than 500 million hours of delay annually on the nation’s highways and principal arterial roads because of fog, snow, and ice, excluding delays due to rain and wet pavement (Qin et al. 2006). Furthermore, 1.5 million vehicular crashes each year, accounting for approximately 800,000 injuries and 7,000 fatalities, are related to adverse weather and the injuries, loss of lives, and property damage from weather related-crashes cost an average of 42 billion dollars in the US annually (Qin et al. 2006). Weather and climate changes have a great impact on surface transportation safety and operations. In the future, with the increase in global warming, transportation managers would need to modify the advisory, control, and treatment strategies to an appropriate level and implement several modern risk mitigation strategies to limit the weather impacts on roadway safety and operations (Pisano et al. 2002). Moreover, weather also acts through visibility impairments, precipitation, high winds, temperature extremes, and lightning to affect driver capabilities, vehicle maneuverability, pavement friction, and roadway infrastructure. According to the National Center for Statistics and Analysis in 2001, the combination of adverse weather and poor pavement conditions contributes to 18 percent of fatal crashes and 22 percent of injury crashes annually (Pisano et al. 2002). The crash risk increases during the rainfall, especially if rain is followed after a period of dry weather. In fact, the crash risk during rainfall was found to be 70 percent higher than the crash risk under clear and dry conditions (Pisano et al. 2008). In winter, however, the drivers adjust their behaviors sufficiently to reduce the crash severity during snowfall but not enough to lower the crash frequency.
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The traffic volumes during snow events were also found to be 30 percent lower than volumes in clear weather signifying that the drivers themselves become cautious and reluctant to travel during a snow event (Pisano et al. 2008). Furthermore, on analysis of the 10 years of winter crash data on Iowa interstates, the crash risk was found to be 3.5 times higher at the start of the winter than it was at the end. Another interesting result propounded by Pisano et al. (2008) was wet weather being much more dangerous when compared to winter weather in terms of both crash frequency and severity. The combination of high traffic volumes, relatively high speeds, and low traction likely explains why most of the weather-related crashes occur during rainfall and on wet pavement. In fact, 47 percent of weather-related crashes happen in the rain and the annual cost of these crashes are estimated nationally between $22 billion (for only those crashes that are reported) and $51 billion (for both the reported and unreported crashes, because about 57 percent of the crashes are not reported to police, according to the National Highway Traffic Safety Administration/NHTSA report by Blincoe et al. (2002)) (Pisano et al. 2008). The different strategies recommended in the research to mitigate these kinds of weather-related risks are advisory (announcing the road weather information prior to the actual event so motorists can take precautionary measures), control (access control, speed management, and weather-related signal timing are the three different types of control that increase road safety), and treatment strategy (includes fixed and mobile anti-icing/deicing systems, chemical sequences, etc.). Several road-weather-management research programs targeted toward traffic, emergency, and winter maintenance management would help to increase the safety, mobility, and productivity of the nation’s roadways and would also benefit national security and environmental quality (Pisano et al. 2008). Research by Goodwin (2003) on best practices for road weather management contained 30 case studies of systems in 21 states that improve the roadway operations under inclement weather conditions including fog, high winds, snow, rain, ice, flooding, tornadoes, hurricanes, and avalanches. This research also mentioned three types of mitigation strategies in response to the control threats: advisory (provide information on prevailing and predicted conditions to both transportation managers and motorists), control (restrict traffic flow and regulate roadway capacity), and treatment strategies (apply resources to roadways to minimize or eliminate weather impacts). The Alabama DOT (ALDOT) developed and installed a low-visibility warning system integrated with a tunnel management system to reduce the impact of low visibility due to fog. The California DOT (Caltrans) developed a motorist warning system for use during low visibility caused by windblown dust in summer and dense localized fog in the winter. Goodwin (2003) reports that in Aurora, Colorado, a maintenance-vehicle management system (MVMS) was implemented to monitor the operation of maintenance vehicles including snowplows and street sweepers. Vehicles were outfitted with MVMS equipment and a global 4
positioning system (GPS), which tracked the location of the vehicles. This information was controlled centrally, allowing for the transmission of pre-programmed, customized messages to a single vehicle, a selected group of vehicles, or to all vehicles. The MVMS could also monitor road treatment activities. With the MVMS monitoring system, transportation managers could easily provide information to citizens about operations and maintenance activities on a particular street or roadway. In addition, treatment costs were minimized and productivity increased 12 percent. Qin et al. (2006) conducted research to investigate the impact of snowstorms on traffic safety in Wisconsin. The temporal distribution of crash occurrences showed that a large percentage of the crashes occurred during the initial stages of the snowstorms, indicating that to be the most risky time of travel on the highways during a snowstorm. The factors responsible for the risks were low friction pavement, which makes operating and maneuvering vehicles difficult, impaired visibility due to blowing snow or fog, which limits drivers’ sight distance, accumulating or drifting snow on the roadway, which covers pavement markings and obstructs vehicles, drivers’ inadequate perception and comprehension of the snowstorm event, and high traffic volumes. The researchers also found that the highest risk of crashes occurred at traffic flow rates from 1,200 to 1,500 vehicles per hour per lane under snow conditions. In the same study, the researchers also found that higher wind speeds/gusts pose high risks causing more severe crashes than higher snowfall intensity. The mitigation strategies suggested by the researchers to render a “passable roadway” (roadway surface free from drifts, snow ridges, ice, and snowpack and can be traveled safely at reasonable speeds without losing traction by the vehicles) were proper winter maintenance operations such as snow plowing and de-icing techniques, like salting and sanding. In the US, the crash frequency was eight times higher on a two-lane highway and 4.5 times higher on a multilane freeway before the deicing techniques were applied than that after the application; the crash frequency was nine times and seven times higher on two-lane highways and multi-lane freeways, respectively, before the application of salt than that after the application, with a crash severity reduction of 30 percent (Qin et al. 2006). The outcomes of this research were as follows: (1) snow plowing and spreader trucks should be sent out prior to the start of the storm event to reduce the number of crashes, (2) the winter maintenance crews should be deployed earlier to significantly reduce crash occurrence, (3) severity of snowstorm and snowfall will increase crash occurrence, and (4) higher wind speed causes more severe crashes (Qin et al. 2006). An interesting result from this study was that freezing rain does not cause more crashes than non-freezing rain, which is counter intuitive given the notoriety of the “black ice” phenomenon pavements. Research by Shi (2010) recommended several best practices for winter road-maintenance activities, including the use of a software tool for computer-aided design of passive snow control
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measures to reduce maintenance costs and closure times, use of anti-icing and pre-wetting techniques, and use of improved weather forecasts through several modern technologies: 1. Road Weather Information Systems/Environmental Sensor Stations (RWIS-ESS), which is an aggregation of roadside sensing and processing equipment used to measure the current weather conditions and road environment such as pavement temperature and pavement conditions in addition to atmospheric conditions and thus aid in winter maintenance decisions 2. Mesonets, which are used as regional networks of weather information integrating the observational data from a variety of sources and thus provide a more comprehensive and accurate picture of the current weather conditions and great potential for improved weather forecasts 3. Fixed Automated Spray Technology (FAST) that is used for anti-icing at key locations enabling the winter maintenance personnel to treat potential conditions before snow and ice problems arise; coupled with RWIS and other reliable weather forecasts, the technology promotes the paradigm shift from being reactive to proactive in fighting winter storms 4. Advanced snowplow technologies, such as automatic vehicle location (AVL), which are vehicle-based sensors, surface-temperature measuring devices, freezing point and ice presence detection sensors, salinity measuring devices, visual and multispectral sensors, and millimeter wavelength radar sensors that have immense importance in winter road-maintenance procedures 5. Maintenance Decision Support Systems (MDSS), which are computer-based systems that integrate current weather observations and forecasts to support maintenance agency response to winter weather events and provides real-time road treatment guidance for each maintenance route Mobile and Short-Duration Operations/Maintenance Activities and Equipment As the highway system reaches the end of its serviceable life, it becomes necessary for transportation agencies to focus on the preservation, rehabilitation, and maintenance of these roads. With significant increase in the number of work-zone activities, transportation officials and contractors are challenged with finding ways to reduce the impact of maintenance activities on driver mobility. In addition, agency leaders are sorting out ways to mitigate risks posed by obstructions to vehicles in work zones. A study by Sorenson et al. (1998) on maintaining customer-driven highways focused on the efforts by the Federal Highway Administration (FHWA) to minimize traffic backups and travel delays caused by highway maintenance, rehabilitation, and reconstruction. The study also investigated traffic management practices and policies intended to cut down on work-zone
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congestion and minimize crash risks. Finally, the study identified contracting and maintenance procedures to cut the time from start to finish in pavement rehabilitation projects. Through extensive interviews with 26 state highway agencies, the research formulated the best traffic management practices and policies that most of the states use to cut down on work-zone congestion and to minimize crash risks for drivers and highway workers. Specific examples of state DOT practices identified in the study are discussed as follows: 1. The Oregon DOT (ODOT) used an innovative contracting technique, awarding contracts based not on the lowest bid, but on a combination of price and qualifications. The innovative contracting introduced a system of awarding incentives if the work is done earlier or a penalty if it is delayed. The use of “lane rental” charged a rental fee to the contractor based on the road user costs for those periods of time when the traffic is obstructed through the lane or shoulder closures. 2. The New Jersey DOT (NJDOT) recommended performing work at night and providing the public with shuttle buses and other transportation alternatives during the construction/rehabilitation of the highways to mitigate the negative impact of the project on the traffic flow. They also assigned a state patrol unit full time to state DOT construction projects to assist with traffic control and increase work-zone safety. 3. The North Carolina DOT (NCDOT) initiated a public information program that informs motorists, businesses, and residents of upcoming road construction and encourages them to use alternate routes. The researchers also interviewed the road users regarding optimizing highway performance and the findings were noteworthy. For example, in addition to reducing traffic congestion caused by work zones, the public demanded the following things: ? ? ? ? ? ? ? Increased public awareness of the highway construction process Longer lasting pavements Non-traditional work schedules such as evening and weekend road closures Upgraded product performance Improved communications with the public—with the help of portable traffic management systems consisting of video detection cameras and a series of variable message signs Educating drivers about how to navigate safely through work zones by using videotapes and other media to describe the construction and rehabilitation process High-performance hot-mix asphalt (HMA) to increase the lifetime of the highways and thus minimize disruptions caused by construction and maintenance work
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Moriarty et al. (2008) examined the impact of preservation, rehabilitation and maintenance activities on traffic. The researchers developed several simulation models to estimate delays, queues, and delay-related costs associated with traffic impacts created by work zones. The simulation results provided a low-risk, low-cost environment and helped in improving the planning and design of work zones; however, these simulation results only provided guidance to the users who must have a fundamental understanding of the highway capacity analyses and traffic flow fundamentals. A study by Paaswell et al. (2006) on traffic control devices for mobile and short-duration operations was conducted to focus on the following: ? ? ? Identification of state-of-the-art work-zone safety technologies to improve worker safety in the mobile work zones Methods for improving the information systems for work-zone traffic control to reduce delays and crashes Introduction of best practices for the use of law enforcement to improve workzone safety along with identifying the key issues to be considered from public outreach and information systems
The study was done in New Jersey for NJDOT and the team found that most of the NJDOT mobile and short-duration work-zone crashes were caused by careless driving, speeding, and motorist inattention. Hence, safety devices should be selected based on their ability to reduce traffic speed through work zones, improve motorists’ recognition of work-zone hazards, and improve motorists’ attention to signs in the work zone. The researchers also noted the Texas DOT (TxDOT) had found operational problems with mobile work-zone configurations that included the improper use of arrow-boards, the lack of uniform procedures for freeway entry and exit, large spacing between caravan vehicles, and unnecessary lane blockage by the caravan. Also included in the report, Caltrans conducted the Caltrans Worker Safety Program, which included construction and maintenance-worker safety orientation and a District Driver Training Program to eliminate employee preventable vehicle accidents (Paaswell et al. 2006). The FHWA recommended the use of automated enforcement and intrusions alarms as well as uniformed police officers to improve traffic safety at highway work zones. Motorists’ information about the work zones, education and outreach systems, and proper training of the workers were mentioned as important factors responsible for decreasing the risks of crashes in mobile work zones. The review of work operations found that safety for mobile operations of pothole patching, sweeping, spraying and mobile patching was in accordance with Manual on Uniform Traffic Control Devices (MUTCD) requirements, but workers requested improved devices such as strobe lights and improved reflective materials for signs to get drivers’ attention (Paaswell et al.
8
(includes flip disk, lightemitting diode, fiber-optic, etc.)
(series of synchronous flashing lights)
FHWA Research Program X X Advanced warning signs X X Flashing lights Dancing diamonds (lights) X Rotating lights/strobe lights X Flashing Stop/Slow paddle All-terrain sign and stand X X Drone radar/speed indicator X Radar-triggered speed displays X Dynamic message signs X Direction indicator barricade X Lighted raised pavement markers X Robotic highway safety markers Variable message signs (VMS) X X Fluorescent/bright lights (yellow/green gives best visibility)
New York State DOT Strategic Highway Research Program
Institution or Agency
New Jersey DOT
Kansas DOT
Special Lights/Signs/Indicators/Markers
Table 1a. Effective technologies/safety devices for mobile operations
2006). The Paaswell study is very thorough and helps provide several informative findings, which are summarized in Tables 1a, 1b, 2, and 3.
9
(attracts drivers’ attention)
X
X
Missouri DOT
FHWA Research Program X Reflectorized/bright suits and vests Remotely-operated auto flagger Truck-mounted attenuators and message boards CB Wizard alert system Rumble strips Lane merger system White lane drop box Shadow vehicles Barrier vehicles Advance warning vehicles Cone shooter X Automated pavement crack sealers Automated debris removal vehicle X Balsi Beam Automated enforcement and intrusion alarms X Vehicle intrusion alarms (both audio and visual) X Salt spreader truck-mounted attenuator (TMA) X Queue detector X Special Instruments/Technologies X X X X X X orange X portable X X X X X X
Strategic Highway Research Program
Kansas DOT California DOT (Caltrans) New York State DOT
Institution or Agency
New Jersey DOT
Table 1b. Effective technologies/safety devices for mobile operations
10
X X X longitudinal and random crack sealers X X X X X
Table 2. Techniques adopted for safer mobile work zones
Reduced Speed Limits Education and Outreach Systems for Training of Workers Uniformed Police Enforcement in Work Zone Reduced Channelization Spacing
Institution or Agency New York State DOT FHWA Research Program
X X
X
Enhanced Flagger Stations
X
X X
Table 3. Criteria satisfied by selected work-zone device/equipment
Work Zone Device Truck-mounted attenuator Vehicle intrusion alarm Rumble strips All-terrain sign and stand Directional indicator barricade Flashing Stop/Slow paddle Opposing traffic lane divider Queue detector Remotely-driven vehicle Portable crash cushion Cone shooter Pavement sealers Debris removal vehicle Balsi Beam Robotic highway safety marker Does not satisfy Partly satisfy Criteria: 1. Reduce exposure to the motorists/crew 2. Warn motorists/crew to minimize the likelihood of crash 3. Minimize severity of crashes once they occur 4. Provide separation between work crew and traffic 5. Improve work zone and traffic control device visibility Fully satisfy 1 2 Criteria 3 4 5
11
The evaluation criteria for device functionality in mobile operations would provide assistance in selecting appropriate traffic control devices for worker safety and the safe and efficient movement of traffic through mobile and short-duration work zones, as shown in Table 3, based on the utility and effectiveness of the devices mentioned in the study. Selected innovative technologies discussed by Paaswell et al. (2006), which show promise for operations and maintenance activities, are discussed in more detail below. Balsi Beam Developed by Caltrans, the Balsi Beam has great potential for protecting exposed workers in short-duration work operations (See Figure 1).
Figure 1. The Balsi Beam being rotated from side to side The beam provides positive protection from errant vehicles and is crashworthy as tested by National Cooperative Highway Research Program (NCHRP) criteria. Unlike portable concrete median barriers, which are labor/equipment intensive to set up and require a 42 in. clear zone between the barrier and the worker, the Balsi Beam can be set up in less than 10 minutes and requires no clear zone between the beam and workers. Caltrans is presently implementing the barrier for specialized concrete construction and bridge repair operations on high-speed interstate highways. The beam can be used in maintenance operations wherever workers are exposed to traffic in a limited area for several hours. Caltrans uses the beam for median barrier repairs, bridge deck patching and repairs, slab replacement and joint repairs, installation of bridge sealers, and guide rail and parapet repairs. The beam is used in conjunction with other safety equipment, such as truck-mounted attenuators, trucks, signs, and safety set up.
12
Dancing Diamonds (light panels) These signs (Figure 2) use a dancing-diamond panel, which is a matrix of light elements capable of either flashing and/or sequential displays and act as an advance caution device.
Figure 2. Dancing diamonds (lights) Rotating Lights/Strobe Lights Rotating/strobe lights were effective in getting drivers’ attention but not as useful in providing speed and closure rate information, especially when the service vehicle has stopped. Portable Rumble Strips Portable rumble strips (Figure 3) are placed temporarily on the road surface at a distance of about 100 meters (250 ft) in advance of the work zone and cause a vibration in the steering wheel and a rumble as vehicles pass over them, alerting drivers of changing conditions ahead and are best suited for low-speed roads that carry few heavy trucks.
Figure 3. Flagger stopping traffic (left) and portable temporary rumble strips being field tested near Perry, Kansas (right)
13
Portable rumble strips are very easy to use as the device weighs only 34 kg (75 lbs) and one or two workers can deploy them from the back of a pick-up truck. Cone Shooter A cone shooter (Figure 4) is a machine that can automatically place and retrieve traffic cones and, thus, open and close busy lanes safely and quickly without exposing workers to traffic.
Figure 4. Cone shooter (photo Copyright © AHMCT Research Center - UC Davis, 2010) Typical lane configurations use 80 traffic cones for each 1.5 miles of lane closure and the cones generally come in the 36 in. size. Manually, only three cones can be carried by a worker at a time, so the cone shooter helps in reducing both the cost and injury involved in a mobile work zone in a busy lane. Automated Pavement Crack Sealers Given that one of the most frequent maintenance operations involves pavement crack sealing and it is done by mobile operations, the Advanced Highway Maintenance and Construction Technology (AHMCT) Research Center has developed two automated crack sealers (Figure 5).
14
Figure 5. Automated pavement crack sealer The longitudinal and random crack sealers perform the operation with greater efficiency and in less time. Robotic Highway Safety Markers The Mechanical Engineering Department at the University of Nebraska-Lincoln has developed a mobile safety barrel robot (Figure 6) for efficient use in mobile work zones.
Figure 6. Robotic safety barrel (RSB)
15
The Robotic Safety Barrel (RSB) replaces the heavy base of a typical safety barrel with a mobile robot. The mobile robot can transport the safety barrel and robots can work in teams to provide traffic control. The robotic highway safety markers have been tested in field environments. Each robot moves individually. A single lead robot (the “General”) provides global planning and control and issues commands to each barrel (the “troops”). All robots operate as a team to close the right lane of a highway. The robotic safety barrels can self-deploy and self-retrieve, removing workers from exposure to moving traffic. The robots move independently so that they can be deployed in parallel and can reconfigure quickly as the work zone changes. These devices would be of great advantage in the mobile work zone where the cones or barrels could be programmed to move along with the working crew, saving time and increasing safety to workers. CB Wizard Alert System and Program CB Wizard is a portable radio that broadcasts real-time work-zone information and safety tips through radio channels. The advanced warning gives drivers the opportunity to moderate their speed and become observant of the need to slow, stop, or maneuver before they reach the work zone or encounter queues of halted vehicles. Truck-Mounted Changeable Message Signs Research at Texas A&M University has identified truck-mounted changeable message signs (TMCMS) (Figure 7) as an innovative technology that improves safety for both drivers and workers (Sun et al. 2011).
Figure 7. Truck-mounted changeable message signs (event example, left, and lane-blocked example, right) (photos Texas A&M University-Kingsville) 16
TMCMS can provide information to drivers in both symbols and text, and the truck-mounted deployment allows the information to be delivered to the driver at the closest possible point to the actual work site. Driver Behavior and Impacts on Truck-Mounted Attenuators Research by Steele and Vavrik (2010) explored driver behavior and identified some specific challenges that pose a risk for mobile work zones and lane closures such as providing adequate advance warning to motorists, decreasing driver speeds and heightening motorist awareness approaching the work zone, getting drivers to change lanes at a safe distance upstream of the work zone, and maintaining traffic in the open lane until a safe distance beyond the work space. The researchers observed that the return distance of the vehicles in the closed lane on urban expressways (high- and low-traffic during daytime) was as early as 25 ft in congested and 50 ft under free-flowing traffic, while the rural interstate traffic was more relaxed, returning to the closed lane 100 ft beyond the lead traffic control truck. However, in all cases, traffic came back into the closed lane at distances where workers would normally be present. It was also observed that increasing the visibility of the work crew by placing a lead truck downstream is an effective means of extending the buffer space at least by 200 ft and deterring drivers from returning to the closed lane too soon. Observation was also made about the workspace length. The analysis of predicted roll-ahead distances for truck-mounted attenuators (TMAs) impacted by vehicles of different sizes and speeds showed that for typical highway speeds, single- and multiple-unit trucks were capable of pushing the TMA into the work space creating a dual threat of lateral intrusions. So, the impacts on TMAs must be considered when developing traffic control standards. An important conclusion was made regarding nighttime mobile lane closure, which created hazardous conditions due to increased traffic speeds, decreased visibility, and increased numbers of impaired drivers. However, the addition of a flashing vehicle on the shoulder of the closed lane and 500 ft upstream reduced the number of vehicles approaching the work zone closely from 18.1 to 3.6 percent. Lighting Effective lighting is very important for service and maintenance vehicles. Although this is not included in the scope of this research work, a summary of three major studies regarding warning lights for service vehicles is provided in Appendix A.
17
Literature Review Conclusions The literature review reveals several studies on the impacts of weather on the roadways and, hence, its effects on work-zone safety, along with specific research on the interaction of traffic and O/M and mobile work-zone-related safety. However, these studies did not specifically address risk assessment and mitigation strategies for the O/M activities on highways. This research study examines weather (environment), equipment, activities, and related factors to develop a risk severity matrix to indicate the relative severity of each factor on a Likert scale of 1 to 5. An analysis of the crash database is also performed to generate a model showing the relationships between the various factors and the severity and frequency of crashes in mobile work zones.
18
RESEARCH METHODOLOGY The purpose of this section is to describe the research methods used to develop the Integrated Risk Management Model and identify, assess, and respond to the risks associated with highway O/M activities, such as pavement testing, pavement marking, painting, shoulder work, mowing, and so forth. As mentioned earlier, the ultimate goal of this research is to reduce the frequency and severity of loss events (property damage, personal injuries, and fatalities) during O/M activities. After potential risk factors were identified and loss frequency and severity had been evaluated, the research team identified risk mitigation strategies that can be used within integrated teams to reduce the frequency and/or severity of losses during O/M activities. The methodologies that were adopted in this research are as follows: ? ? ? ? ? Identification of current O/M processes through expert input Literature review Analysis of the crash data Validation survey Identification of mitigation strategies
Identification of Current O/M processes through Expert Input The research started with an expert panel session aimed at mapping the O/M process as currently utilized by state, county, and local agencies. The objective was to categorize the activities, environments, tools/equipment, and relationships involved with different operations and maintenance functions. The outcomes of the expert panel (technical advisory committee or TAC) session are described in Appendix B. Appendix C contains in-depth follow-up interviews with three members of the expert panel (Bob Younie, Mark Black, and Jeff Koudelka). Literature Review An extensive literature search was performed and a preliminary list of risk factors and loss events during O/M activities was identified. The search mainly included results from academic journals, trade publications, transportation research technical reports, and state DOT web sites. The primary websites used to facilitate the search for relevant publications were Google Scholar, the Transportation Research Board (TRB), Parks Library at Iowa State University, and the Iowa DOT Library. The literature search also gave insight into how the identified factors play a role in mobile work-zone crashes, specifically work zones that involve O/M activities on highways.
19
Analysis of the Crash Data The analysis of the crash database provided by the Iowa DOT played a very important role in the development of the Integrated Risk Management Model. To obtain information about the relevant crashes, a query was created to gather data for all severity level of crashes from 2001 through 2010 that involved two types of work zones (given we were focused on moving operations and not static work): intermittent or moving work and work on shoulder or median. The suitable variables in the crash database that were able to explain the effect of the previouslyidentified factors (activities, environment, tools/equipment, and relationships) were queried to analyze their effect on crash severities and the frequency with which they occur within the database. Table 4 shows the variables selected from the crash database to analyze the risk posed by each of the factors in O/M activities. Table 4. Variables queried from the Iowa crash database
Data Field (crash data) and Field Description Crash Severity CSEVERITY: Crash severities as measured Categories Fatal Major Injury Minor Injury Possible or Unknown Injury Property Damage Only (PDO) 1. 2. Work on shoulder or median Intermittent or moving work
Activity WZ_Type: Type of work activities involved Equipment FIRSTHARM: What the first harmful event is collision with SEQEVENTS1: In the sequence of events, what the first event is collision with EmerVeh: Emergency vehicle type EmerStatus: Emergency status of the vehicle considered VCONFIG: Vehicles involved in the crash
Impact Attenuator (fixed object) Impact Attenuator (fixed object)
Maintenance Vehicle 1. In emergency 2. Not in emergency 1. 2. 3. 4. 5. 6. 7. Passenger car Four-tire light truck Van or mini-van Motor home /recreational vehicle Motorcycle and sport utility vehicle Mopeds/Motorcycle Trucks and tractors (Single-unit truck two-axle, Single-unit truck ? three axles, Truck/trailer, Truck tractor, Tractor/semitrailer, Tractor/doubles, Tractor/triples and other heavy trucks) Bus (School bus > 15 seats, Small school bus nine to 15 seats, Other bus > 15 seats, and Other small bus nine to 15 seats) Maintenance or construction vehicle
8. 9.
20
Data Field (crash data) and Field Description Environment LIGHTING: Derived light conditions
Categories 1. Daylight 2. Darkness 3. Morning Twilight 4. Evening Twilight 1. Moving vehicles 2. Frosted windows/windshield 3. Blowing snow 4. Fog/smoke/dust Work-zone signs Mainline or ramp 1. Interstate 2. US Route 3. Iowa Route 4. Secondary Route 5. Municipal Route 6. Institutional Road 1. Work zone (construction/maintenance/utility) 2. Traffic control device inoperative/missing/obscured 1. 2. 3. 4. 5. 6. 1. 2. 3. 4. 5. 6. Cloudy Fog, smoke Rain Sleet, hail, freezing rain Snow Blowing sand, soil, dirt, snow Before work-zone warning sign Between advance warning sign and work area Within transition area for lane shift Within or adjacent to work activity Between end of work area and End Work Zone sign Other Driver ?18 years Driver > 18 and 15 seats, and Other small bus with nine to 15 seats) Vehicle configuration involved in crash is a maintenance/construction vehicle Daylight crash Crash when no daylight, i.e., during Darkness, Morning Twilight, or Evening Twilight Vision not obscured by anything Vision obstructed by frosted windows or windshield Vision obstructed by moving vehicle 0.0004 0.0001 0.0068 0.0016 0.0052 0.54293085 0.139875 0.10264889 0.11316813 0.0772 Variable Description Frequency Significance Indicator
BUS
0.0049
VCNFIGCO Environment DAYLIT NODAYLIT VNOBSCUR VOFROSTW VOMOVVEH
0.0077
0.8821 0.1180 0.9164 0.0002 0.0116
27
Variables VOWEATHE NOTFCONT TRAFCONW LOCRAMP LOCMAIN INTERSTA USROUTE IOWAROUT SECROAD MUNIROAD INSTROAD RCNTCIRC
Variable Description Vision obstructed by weather like blowing snow, fog, smoke, or dust No traffic control present near the work zone where the crash occurs Traffic control present near the crash work zone involves work-zone sign Crash location is near the ramp Crash location near the mainline Interstate route US route Iowa route Secondary road Municipal road Institutional road Contributing circumstances of the crash involves work-zone (construction/ maintenance/utility) Contributing circumstances of the crash involves inoperative/obscured/missing traffic control device Weather condition has blowing snow Weather condition is cloudy Weather condition is foggy or smoky Weather condition has rain Weather condition has snow Crash location is between the advance warning sign and work area Crash location is within or adjacent to the work activity Driver ? 18 years Driver > 18 and < 25 years 28
Frequency 0.0068 0.7293 0.0912 0.0545 0.9455 0.6305 0.1306 0.068 0.0545 0.1137 0.0009 0.9509
Significance Indicator
CNTNCRCTC
0.0006
BLOWSNOW CLOUDY FOGSMOKE RAIN SNOW BETAWWRK WTHWRKZN
0.0027 0.1129 0.0026 0.1633 0.0024 0.1663 0.6921
Driver Characteristics UNDDRI YONDRI 0.0594 0.2244
Variables MDDRI OLDRI VOLDRI IOWALCNC X16 OFSMLDR OFSFMDR
Variable Description Driver ? 25 and < 45 years Driver ? 45 and < 65 years Driver ? 65 years Iowa driver’s license Driver gender (male = 1, female = 0) Out-of-state male driver Out-of-state female driver
Frequency 0.3499 0.3304 0.0641 0.7904 0.5124 0.1587 0.1002
Significance Indicator
The final model of the crash severities was selected after a reiterative selection of the different independent variables through the LIMDEP software, which are shown in Table 7 with their beta coefficient and statistical significance.
29
Table 7. Variable description and results ID 1 2 Indicator/Variable Description Constant Crash Location Indicator 1 ( 1 if the crash location is between the advance warning sign and work area; 0 if otherwise) Crash Location Indicator 2 (1 if the crash location is within or adjacent to the work activity; 0 if otherwise) Crash Location Indicator 3 (1 if the location of the crash is near the ramp; 0 if otherwise) Cloudy Weather Indicator ( 1 if the weather condition is cloudy; 0 if otherwise) Under-Aged Driver Indicator (1 if driver ? 18 years; 0 if otherwise) Young-Aged Driver Indicator (1 if driver > 18 and < 25 years; 0 if otherwise) Middle-Aged Driver Indicator ( 1 if driver ? 25 and < 45 years; 0 if otherwise) Old-Aged Driver Indicator (1 if driver ? 45 and < 65 years; 0 if otherwise) Very Old-Aged Driver Indicator (1 if driver ? 65 years; 0 if otherwise) Time of Day Crash Indicator (1 if no daylight, i.e., either in darkness, morning twilight, or evening twilight; 0 if otherwise) Out-of-State Male Driver Indicator (1 if out-of-state male driver; 0 if otherwise) Out-of-State Female Driver Indicator (1 if out-of-state female driver; 0 if otherwise) Rain Indicator (1 if rain; 0 if otherwise) Interstate Route Indicator (1 if Interstate; 0 if otherwise) Variable Mnemonic Constant BETAWWRK Estimated Coefficient
-1.984366***
T-Statistic
-15.004 45.373
.91979447***
3
WTHWRKZN
.340550***
19.633
4
LOCRAMP
.107263***
4.445
5
CLOUDY
.8491091***
49.481
6 7
UNDDRI YONDRI
-.419101*** -.507994***
-9.814
-12.772
8
MDDRI
-.2448169***
-6.439
9
OLDRI
-.2721166***
-7.067
10 11
VOLDRI NODAYLIT
.1761806***
8.132
28.701
.4889586***
12
OFSMLDR
.1177997***
6.898
13
OFSFMDR
-.235061***
-9.695
14 15
RAIN INTERSTA
-.292615*** .551989***
-15.717 4.393
30
ID 16
Overall fit by ? - Square
Indicator/Variable Description US Route Indicator (1 if US Route; 0 if otherwise) 17 Secondary Road Indicator (1 if Secondary Route; 0 if otherwise) 18 Municipal Route Indicator (1 if Municipal Route; 0 if otherwise) 19 Iowa Route Indicator (1 if Iowa Route; 0 if otherwise) 20 Traffic Control Sign Indicator (1 if traffic control present near the crash work zone involves work-zone sign; 0 if otherwise) 21 Passenger Vehicle Indicator (1 if Passenger vehicle; 0 if otherwise) 22 Pick-up Truck Indicator (1 if fourtire light truck/pick-up truck; 0 if otherwise) 23 Van Indicator (1 if Van or Minivan; 0 if otherwise) 24 Truck and Tractor Indicator (1 if Single-unit truck two-axle, Singleunit truck ? three axles, Truck/trailer, Truck tractor, Tractor/semi-trailer, Tractor/doubles, Tractor/triples and other heavy trucks; 0 if otherwise) 25 Vision Not Obscured Indicator (1 if vision not obscured by any of the hindrances like moving vehicles, weather, etc., during the crash; 0 if otherwise) 26 Gender Indicator (1 if male driver; 0 if female driver) Threshold Parameter 27 ?1 28 ?2 NO. OF OBSERVATIONS Log likelihood function [LL(?)]
Variable Mnemonic USROUTE SECROAD MUNIROAD IOWAROUT TRAFCONW
Estimated Coefficient
1.191032*** 1.43160*** 1.112705*** 1.18880*** .02326043*
T-Statistic
9.434 11.252 8.800 9.367 1.28
PSVEH PCKTRK
.432212*** .353129***
25.049 16.581
VAN TRCKTRAC
.437940*** .535388***
19.581 21.932
VNOBSCUR
.328564***
14.660
X16
-.035858***
-3.008
.7617741*** 1.915051*** 55042 -49179.94
125.083 158.255
Restricted log likelihood [LL(C)] -54910.88 ? - Square = 1-LL(?)/LL(C) 0.104368023 adjusted ? - Square = 1-(LL(?)-k) 0.103858106 /LL(C)
31
k= number of parameters in the model K (No. of parameters in the unrestricted – No. of parameters in the restricted model] -2 [LL(?c) – LL(?)] X2critical [25 d.f.] Given that -2 [LL(?c) – LL(?)] > X2critical at significant at 99.99%. Overall fit by X2 estimate
28 28-3=25
11461.88 60.1403 ?=0.0001, we can state that the entire model is
***, **, * = Significance at 1%, 5%, 10% level, respectively For detailed statistical analysis, refer to Sayanti (2011) master’s thesis upon publication/distribution of it
The marginal effects for each response category are interpreted as a change in the outcome probability of each threshold category P(y=j) given a unit change in a continuous variable x (Washington et al. 2010). These values are dimensionless and relative and also do not carry any specific meaning. There are in fact two ways of estimating how much the event probability changes when a given predictor is changed by one unit. The marginal effect of a predictor is defined as the partial derivative of the event probability with respect to the predictor of interest. A more direct measure is the change in predicted probability for a unit change in the predictor. Being a derivative, the marginal effect is the slope of the line that is drawn tangent to the fitted probability curve at the selected point. Note that the marginal effects depend on the variable settings that correspond to the selected point at which this tangent line is drawn, so the marginal effect of a variable is not constant. Table 8 depicts the marginal effects of the factors. Marginal effect of any factor can be defined as the effect a positive or a negative coefficient has on the probabilities of the crash severity. For example, if we consider BETAWWRK (the crash location is between the advance warning sign and work area), the probability of the crash being fatal/major is 0.0595 higher (on average), the probability for the crash being a minor injury is 0.203 higher (on average), and the probability for the crash being a probable or unknown injury is 0.0917 higher (on average); whereas, the probability of the crash being a PDO is 0.3541 lower (on average). Thus, marginal effects portray the impact each factor has on the potential severity of the crash.
32
Table 8. Marginal effects of the factors along with their severities Probability of the factors causing possible/ unknown injury crashes
0.0917 0.082 -0.0716 -0.0851 -0.0398 -0.0445 0.0264 0.0635 0.0183 -0.0394 -0.049 0.0895 0.0793 0.0288 0.0781 0.06 0.0687 0.0499 0.0581 0.0653 0.0037 0.0557 0.056 0.0165 -0.0057
Significant variables affecting severity
BETAWWRK CLOUDY UNDDRI YONDRI MDDRI OLDRI VOLDRI NODAYLIT OFSMLDR OFSFMDR RAIN INTERSTA USROUTE SECROAD MUNIROAD IOWAROUT PSVEH PCKTRK VAN TRCKTRAC TRAFCONW VNOBSCUR WTHWRKZN LOCRAMP X16 Weighting Factors Total Weighting
Probability of the factors causing fatal-major crashes
0.0595 0.0564 -0.0087 -0.0119 -0.007 -0.0076 0.0065 0.0233 0.004 -0.0059 -0.0073 0.0152 0.102 0.1719 0.0924 0.1145 0.0132 0.0147 0.0202 0.0278 0.0007 0.0075 0.0092 0.0037 -0.0011
Probability of the factors causing minor crashes
0.203 0.1904 -0.064 -0.0815 -0.0436 -0.0481 0.0348 0.1039 0.0225 -0.0396 -0.0491 0.0948 0.2655 0.3069 0.2503 0.2679 0.0782 0.0723 0.0924 0.1164 0.0043 0.0529 0.059 0.0207 -0.0066
Probability of the factors causing PDO
-0.3541 -0.3288 0.1443 0.1784 0.0905 0.1002 -0.0677 -0.1907 -0.0448 0.0849 0.1054 -0.1995 -0.4468 -0.5076 -0.4208 -0.4423 -0.1601 -0.1368 -0.1708 -0.2095 -0.0088 -0.1161 -0.1242 -0.0409 0.0135
Weighted Average of the Probabilities of the factors causing several severe crashes
0.0672** 0.0629 -0.0219 -0.0276 -0.0144 -0.0159 0.0113 0.0336 0.0074 -0.0133 -0.0165 0.0316 0.0921 0.1185 0.0859 0.0949 0.0258 0.0234 0.0298 0.0377 0.0014 0.0179 0.0196 0.0067 -0.0022
4.5
3
2
1
10.5
Calculation of the Weighted Average of the Probability (example): 0.067242857** = (0.0595 × 4.5 + 0.203 × 3 + 0.917 × 2 - 0.3541 × 1) ÷ 10.5
33
To rank the factors in terms of their impact on severity, a weighted average technique was adopted. The weighted average of the probabilities of the factors is calculated to give an overall severity value. The different categories of the crashes are assigned ranking factors based on their importance and impact and they are as follows: ? ? ? ? ? Fatal – 5 Major Injury – 4 Minor Injury – 3 Probable/Unknown Injury – 2 PDO – 1
Given the fatal and major injury crashes have been combined, the average of the ranking factors 5 and 4 (4.5) is assigned to the Fatal/Major Injury crash category. Therefore, for this research, the ranking factors are as follows: ? ? ? ? Fatal/Major Injury – 4.5 Minor Injury – 3 Probable/Unknown Injury – 2 PDO – 1
The calculation of the weighted average for the probabilities is shown in Table 8. Figure 10 shows the distribution of the factors according to the weighted average of the probabilities for the occurrence of the different types of crashes, which is referred to as the severity of the factors in this report.
34
Weighted average of the Probabilities of the crashes to cause more FatalMajor, Minor, Probable/Unknown and a PDO
0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 -0.02 -0.04 BETAWWRK CLOUDY UNDDRI YONDRI MDDRI OLDRI VOLDRI NODAYLIT OFSMLDR OFSFMDR RAIN INTERSTA USROUTE SECROAD MUNIROAD IOWAROUT PSVEH PCKTRK VAN TRCKTRAC TRAFCONW VNOBSCUR WTHWRKZN LOCRAMP X16 Weighted average of the Probabilities of the crashes to more FatalMajor, Minor,Probable /Unknown and a PDO
Figure 10. Distribution of the weighted average for the probabilities of the factors for the occurrence of the different types of crashes The factors showing higher positive probabilities are more likely to cause a Fatal/Major Injury crash; whereas, those showing a negative probability indicate they are more likely to cause a PDO crash. To rank the factors on a scale of one to five based on the severity (5 being the most severe and 1 being the least severe), the probability distribution is categorized into five distinct levels: ? ? ? ? ? Less than 0 = 1 0 - 0.02 = 2 0.02 - 0.04 = 3 0.04 - 0.08 = 4 Greater than 0.08 = 5
Following this scale, the significant factors are ranked from most severe to least severe (generally from top to bottom) as shown in Table 9.
35
Table 9. Ranking of the factors according to severity Variable
USROUTE SECROAD MUNIROAD IOWAROUT BETAWWRK CLOUDY NODAYLIT INTERSTA PSVEH PCKTRK VAN TRCKTRAC VOLDRI OFSMLDR TRAFCONW VNOBSCUR WTHWRKZN LOCRAMP UNDDRI YONDRI MDDRI OLDRI OFSFMDR RAIN X16
Severity Ranking
5 5 5 5 4 4 3 3 3 3 3 3 2 2 2 2 2 2 1 1 1 1 1 1 1
Frequency Analysis and Factor Rating According to Frequency Risk is defined as the combined effect of the severity (i.e., the impact) and frequency (i.e., the likelihood of occurrence). Therefore, the impact the factors have on severity cannot by itself predict the magnitude of risk that those factors possess for O/M activities on the highways. Frequency of the factors plays a major role in determining the risk value of the factors and develops the Integrated Risk Management Model. The number of times that the factors are involved in each type of crash is illustrated in Table 10. Along with the frequencies of occurrence of the factors shown in Table 10, the frequency distribution is shown in Figure 11.
36
Table 10. Frequency distribution of the factors Significant Variables Affecting Severity BETAWWRK CLOUDY UNDDRI YONDRI MDDRI OLDRI VOLDRI NODAYLIT OFSMLDR OFSFMDR RAIN INTERSTA USROUTE SECROAD MUNIROAD IOWAROUT PSVEH PCKTRK VAN TRCKTRAC TRAFCONW VNOBSCUR WTHWRKZN LOCRAMP X16 Total Fatal/ Major Injury Crashes 97 83 26 51 491 485 146 117 336 263 99 600 455 184 19 64 433 294 189 323 311 1,038 1,056 17 865 Minor Injury Crashes 2,345 2,835 928 1,969 2,428 2,794 582 2,916 913 178 1,379 3,242 1,624 268 1,828 1,272 6,097 756 587 385 641 7,933 5,189 164 3,766 Possible Injury Crashes 3,038 1,131 458 1,615 4,516 4,687 1,277 562 1,529 850 359 6,798 1,474 1,513 1,144 486 5,652 1,721 1,540 910 1,125 10,551 6,857 877 6,163 Frequency Distribution (%) 16.63 11.29 5.94 22.44 34.99 33.04 6.41 11.79 15.87 10.02 16.33 63.05 13.06 5.45 11.37 6.80 54.29 13.99 10.26 7.72 9.12 91.64 69.21 5.45 51.24
PDO Crashes 3,675 2,165 1,859 8,715 11,825 10,220 1,525 2,897 5,956 4,224 7,154 24,065 3,633 1,035 3,268 1,922 17,702 4,928 3,334 2,630 2,941 30,919 24,995 1,941 17,412
Total 9,155 6,214 3,271 12,350 19,260 18,186 3,530 6,492 8,734 5,515 8,991 34,705 7,186 3,000 6,259 3,744 29,884 7,699 5,650 4,248 5,018 50,441 38,097 2,999 28,206 55,042
37
Frequency of the significant factors present in all the crashes Frequency of the significant factors present in all the crashes
100.00 90.00 80.00 70.00 60.00 50.00 40.00 30.00 20.00 10.00 0.00 BETAWWRK CLOUDY UNDDRI YONDRI MDDRI OLDRI VOLDRI NODAYLIT OFSMLDR OFSFMDR RAIN INTERSTA USROUTE SECROAD MUNIROAD IOWAROUT PSVEH PCKTRK VAN TRCKTRAC TRAFCONW VNOBSCUR WTHWRKZN LOCRAMP X16 Series1
Significant variables Figure 11. Distribution of the percentage frequency of the factors (crash database) present in all crashes involving intermittent and moving work zones and work on the shoulders and median To rank these significant factors according to their frequency of occurrence on a scale of one to five (1 being the least frequently occurring factor and 5 being the most frequently occurring factor), the percentage frequency scale is categorized into five levels as follows: ? ? ? ? ? 0 - 9.99 = 1 10.00 - 19.99 = 2 20.00 - 39.99 = 3 40.00 - 59.99 = 4 Greater than 60.00 = 5
Following this categorization protocol, the factors can be ranked according to their frequency of occurrence as shown in Table: 11.
38
Table 11. Ranking of significant factors according to their frequency of occurrence Frequency Variables Ranking INTERSTA 5 VNOBSCUR 5 WTHWRKZN 5 PSVEH 4 X16 4 YONDRI 3 MDDRI 3 OLDRI 3 BETAWWRK 2 CLOUDY 2 NODAYLIT 2 OFSMLDR 2 RAIN 2 USROUTE 2 MUNIROAD 2 PCKTRK 2 UNDDRI 1 VOLDRI 1 OFSFMDR 1 SECROAD 1 IOWAROUT 1 VAN 1 TRCKTRAC 1 TRAFCONW 1 LOCRAMP 1
Risk Rating of the Factors Risk can be defined mathematically as the product of the severity or impact of the factors and the frequency of occurrence of the factors. This combined estimate of the severity and frequency of occurrence gives an assessment of risk posed by the hazard and helps decision makers prioritize which hazards to address, assists in safety planning, and facilitates the development of risk mitigation strategies. Risk values are assigned to the significant factors as shown in Table 12.
39
Table 12. Risk values of the significant factors Severity Frequency Risk Variables Ranking Ranking Assessment INTERSTA 3 5 15 PSVEH 3 4 12 USROUTE 5 2 10 MUNIROAD 5 2 10 VNOBSCUR 2 5 10 WTHWRKZN 2 5 10 BETAWWRK 4 2 8 CLOUDY 4 2 8 NODAYLIT 3 2 6 PCKTRK 3 2 6 SECROAD 5 1 5 IOWAROUT 5 1 5 OFSMLDR 2 2 4 X16 1 4 4 YONDRI 1 3 3 MDDRI 1 3 3 OLDRI 1 3 3 VAN 3 1 3 TRCKTRAC 3 1 3 VOLDRI 2 1 2 RAIN 1 2 2 TRAFCONW 2 1 2 LOCRAMP 2 1 2 UNDDRI 1 1 1 OFSFMDR 1 1 1 Validation Survey Data Analysis Results In the validation survey, 33 responses were obtained, of which 24 were complete responses and nine were partial responses but missing answers to the open-ended questions. The responses were compiled in the form of percentages of participants selecting that particular category of a particular question. Table 13 illustrates the levels of probable severities and Table 14 illustrates the probable frequency of occurrence of the different factors (i.e., hazards), under activity, environment, equipment, and other, which the participants anticipated from their experiences.
40
Table 13. Severity levels of the factor Severity Weighted Average of the Severity 0.1280 0.0800 0.1700 0.1747 0.1460 0.2127 Potential Property Damage Minor Property Damage and/or Minor Injuries Major Property Damage and/or Major Injuries 4 0.22 0.06 0.26 0.22 0.28 0.16 0.19 0.26 0.19 0 0 0.19 0.22 0.31 0.16 0.34 0.11 0.26 0.27
ID Activity FWD structural testing on 1 pavement and subgrade Ride quality testing on 2 pavement or bridge surface 3 Core drilling on pavements Manual condition surveys for 4 pavement section Bridges and culvert repair and 5 inspection 6 Mowing Movement of street 7 sweeper/street cleaner Straddling painting (centerline 8 painting) Offset painting (edge-line 9 painting) on four-lane divided highway Offset painting (edge-line 10 painting) on two-lane twoway traffic roadway 11 Pavement markings 12 Crack filling/patch work 13 Curb and surface repairs 14 Flagger operations Replacing/repairing the 15 signals and signage Loading/unloading material 16 for maintenance operations on four-lane divided highway Loading/unloading material 17 for maintenance operations on two-lane two-way road
1 0.06 0.16 0.03 0.12 0.06 0.12 0.16 0.06 0.09
2 0.16 0.16 0.16 0.09 0.12 0.16 0.22 0.26 0.28
3 0.22 0.16 0.16 0.06 0.16 0.34 0.16 0.26 0.25
0.06 0.03 0.09 0.06 0.16 0.15 0.15
0.32 0.25 0.12 0.19 0.06 0.22 0.22
0.23 0.28 0.25 0.32 0.25 0.33 0.19
0.12
0.23
0.19
41
Catastrophic Loss/Fatality 5 0.06 0.06 0.03 0.16
No Loss
0.03 0.1347 0.06 0.1107 0.06 0.1467 0.03 0.1500 0.03 0.1327 0.06 0.1800 0.03 0.1540
0.06 0.1633
0.07 0.1580 0.07 0.1700
0.08 0.1753
Severity Weighted Average of the Severity 0.1433 0.1100 0.1800 0.1480 0.2133 Potential Property Damage Minor Property Damage and/or Minor Injuries Major Property Damage and/or Major Injuries 0.15 0.33 0.27 0.26 0.19 0.15 0.08 0.19 0.37 0.23 0.22 0.4 0.08 0.28 0.36
ID 18
Shoulder grading Repair, maintenance, and installation of guardrails, 19 cable rails, and barrier rails on four-lane divided highway Repair, maintenance, and installation of guardrails, 20 cable rails, and barrier rails on two-way two-lane road Repair, maintenance, and installation of centerline 21 guardrails, cable rails, and barrier rails on four-lane divided traffic roadway Maintenance of sanitary and 22 storm sewer and water main 23 Ditch cleaning Cleaning storm sewer intakes 24 and structures 25 Survey work Ingress and egress from 26 construction site Electric/power system 27 maintenance and street lighting 28 Snow removal Environment 29 Nighttime operations Presence of small towns or 30 schools nearby Improper signs and signage at 31 ramps and roadway intersections near work zones Pavement markings at 32 intersections at nighttime
0.12 0.04
0.31 0.22
0.27 0.19
0.04
0.31
0.12
0.11
0.22
0.19
0.07 0.23 0.24 0.3 0.15 0.04 0 0.04 0.2 0.08 0.12
0.41 0.35 0.28 0.19 0.04 0.35 0.22 0.08 0.24 0.08 0.08
0.04 0.04 0.08 0 0.33 0.12 0.3 0.16 0.24 0.28 0.24
42
Catastrophic Loss/Fatality 0 0 0 0 0.2
No Loss
0.07 0.1813
0.12 0.1800
0.07 0.1673
0.04 0.1313
0.04 0.1040 0.11 0.1327
0.04 0.1480
0.24 0.2320 0.04 0.1280
0.08 0.1893
Severity Weighted Average of the Severity 0.1573 0.1120 0.1360 0.0893 0.1627 0.0993 0.1733 0.0820 0.1053 0.1613 Potential Property Damage Minor Property Damage and/or Minor Injuries Major Property Damage and/or Major Injuries 0.16 0.32 0.6 0.33 0.36 0.2 0.28 0.4 0.2 0.08 0.13 0.18 0.09 0.22 0.09 0.17 0.26 0.26 0.22
ID 33 34 35 Pavement markings at intersections at daytime Work zones on roads in hilly areas Peak traffic hours Lack of knowledge about variable peak traffic time in local regions near work zone (e.g., variable travel patterns near institutions like the Iowa DOT, University, and Animal Disease Lab in Ames, Iowa) Work near railway crossings Clearing roadway for emergency vehicles Unforeseen weather conditions Fog and mist Different rules in shared jurisdictions Special events such as parades, races, and fairs in local cities and towns
0.12 0.08 0.08
0.2 0.04 0.04
0.4 0.36 0.2
36
0.08
0.04
0.33
37 38 39 40 41 42
0.12 0.16 0.12 0.08 0.16 0.16
0.16 0.12 0.28 0.08 0.24 0.24
0.08 0.32 0.16 0.32 0.08 0.36
Equipment 43 Falling-weight deflectometer 44 Straddling painters 45 Maintainers on gravel roads 46 Cold-mix patchwork 47 Friction testing 48 Media trucks Trucks carrying rock/ 49 aggregate 50 Boom trucks 51 Pick-up trucks
0.17 0.05 0.04 0.09 0.22 0.3 0.04 0.13 0.22
0.13 0.23 0.35 0.26 0.13 0.3 0.22 0.22 0.22
0.13 0.32 0.13 0.22 0.13 0 0.3 0.17 0.17
43
Catastrophic Loss/Fatality 0 0 0 0 0.05 0 0.09 0 0 0
No Loss
0.16 0.2213 0.08 0.2373
0.08 0.1913
0.12 0.1813 0.04 0.1573 0.12 0.1920 0.12 0.2267
0.04 0.1547 0 0.1367
Severity Weighted Average of the Severity 0.1353 0.1093 0.1153 0.1220 Potential Property Damage Minor Property Damage and/or Minor Injuries Major Property Damage and/or Major Injuries 0.17 0.13 0.22 0.36 0.3 0.26 0.17 0.04 0.17 0.22 0.22 0.13 0.14 0.3
ID 52 53 54 55 56 57 Other 58 59 60 61 62 63 64 65
Street sweepers/street cleaners 0.13 Jet vac Paint carts (hauled on trailers) Absence of proper signage near work zone Absence of fluorescent diamond signs Not using lights/blinkers in work zone Lack of coordination with municipalities Work done under full closure Lack of coordination between state and local agencies Lack of work safety and training programs Absence of train-the-trainers philosophy Lack of coordination between DOT and utilities regarding control of ROW Improper third-party interaction Not imposing speed limit fines on public 0.17 0.13 0.09 0.13 0.09
0.22 0.22 0.3 0 0.09 0.17
0.26 0.17 0.04 0.23 0.26 0.17
0.26 0.57 0.26 0.09 0.17 0.35 0.18 0.09
0.13 0.13 0.09 0.04 0.04 0.09 0.14 0.09
0.26 0.13 0.26 0.26 0.22 0.17 0.27 0.26
44
Catastrophic Loss/Fatality 0 0 0 0
No Loss
0.27 0.2380 0.13 0.1960 0.22 0.2053
0.04 0.1453 0.13 0.1353 0.04 0.1400 0.35 0.2387 0.22 0.1927 0.04 0.1173
0.22 0.2233
Table 14. Frequency distribution of the factors Frequency Very Probable 5 0 0 0 0 0 0 0 0.06 0.03 0.1120 0.1080 0.1300 0.1053 0.1413 0.1240 0.1380 0.1967 0.1733 0.03 0.03 0 0 0.06 0.04 0.11 0.08 Very Unlikely Weighted Average of Likelihood of Occurrence 0.1640 0.1720 0.1733 0.1540 0.1947 0.1560 0.1760 0.1913
ID Activity FWD structural testing on 1 pavement and subgrade Ride quality testing on 2 pavement or bridge surface 3 Core drilling on pavements Manual condition surveys for 4 pavement section Bridges and culvert repair and 5 inspection 6 Mowing Movement of street 7 sweeper/street cleaner Straddling painting (centerline 8 painting) Offset painting (edge-line 9 painting) on four-lane divided highway Offset painting (edge-line 10 painting) on two-lane two-way traffic roadway 11 Pavement markings 12 Crack filling/patch work 13 Curb and surface repairs 14 Flagger operations Replacing/repairing the signals 15 and signage Loading/unloading material for 16 maintenance operations on four-lane divided highway Loading/unloading material for 17 maintenance operations on two-lane two-way road
1 0.12 0.12 0.09 0.1 0.07 0.19 0.12 0.03 0.1
2 0.12 0.19 0.25 0.19 0.23 0.29 0.19 0.26 0.19
3 0.28 0.16 0.16 0.06 0.13 0.19 0.19 0.1 0.23
4 0.12 0.16 0.22 0.23 0.3 0.13 0.25 0.45 0.32
0.06 0.06 0.12 0.03 0.12 0.11 0.07
0.25 0.16 0.09 0.23 0.12 0.3 0.3
0.25 0.31 0.22 0.3 0.34 0.33 0.22
0.25 0.28 0.41 0.23 0.31 0.11 0.19
0.08
0.23
0.23
0.31
45
Probable
Unlikely
Neutral
Frequency Very Probable 0 0 0 0 0 0 0 0.04 0.04 0 0 0.17 0.04 0.16 0.16 0.04 Very Unlikely Weighted Average of Likelihood of Occurrence 0.1307 0.1587 0.1633 0.1580 0.1187 0.0993 0.1160 0.1293 0.2020 0.1300 0.1727 0.2507 0.1547 0.2267 0.2240 0.1893
ID 18
Shoulder grading Repair, maintenance, and installation of guardrails, cable 19 rails, and barrier rails on fourlane divided highway Repair, maintenance, and installation of guardrails, cable 20 rails, and barrier rails on twoway two-lane road Repair, maintenance, and installation of centerline 21 guardrails, cable rails, and barrier rails on four-lane divided traffic roadway Maintenance of sanitary and 22 storm sewer and water main 23 Ditch cleaning Cleaning storm sewer intakes 24 and structures 25 Survey work Ingress and egress from 26 construction site Electric/power system 27 maintenance and street lighting 28 Snow removal Environment 29 Nighttime operations Presence of small towns or 30 schools nearby Improper signs and signage at 31 ramps and roadway intersections near work zones Pavement markings at 32 intersections at nighttime Pavement markings at 33 intersections at daytime
0.07 0.07
0.37 0.22
0.33 0.37
0.04 0.19
0.07
0.22
0.3
0.26
0.11
0.11
0.48
0.15
0.11 0.22 0.15 0.22 0.04 0.12 0 0 0 0.12 0 0.04
0.33 0.33 0.35 0.15 0.15 0.19 0.11 0.04 0.32 0 0.08 0.04
0.19 0.11 0.19 0.26 0.19 0.23 0.15 0.17 0.28 0.08 0.16 0.52
0.11 0.07 0.08 0.11 0.48 0.19 0.48 0.58 0.16 0.56 0.48 0.24
46
Probable
Unlikely
Neutral
Frequency Very Probable 0.12 0.24 0.12 0.04 0.17 0.16 0.24 0.12 0.12 0 0 0 0 0 0 0.04 0 0 0 0 0.04 Very Unlikely Weighted Average of Likelihood of Occurrence 0.2420 0.2773 0.2153 0.1627 0.2013 0.2293 0.2533 0.1547 0.1947 0.0993 0.1760 0.1053 0.1587 0.0860 0.1213 0.1607 0.1467 0.1320 0.1413 0.1240 0.1447
ID 34 35 Work zones on roads in hilly areas Peak traffic hours Lack of knowledge about variable peak traffic time in local regions near work zone (e.g., variable travel patterns near institutions like the Iowa DOT, University, and Animal Disease Lab in Ames, Iowa) Work near railway crossings Clearing roadway for emergency vehicles Unforeseen weather conditions Fog and mist Different rules in shared jurisdictions Special events such as parades, races, and fairs in local cities and towns 0 0
0 0
0.29 0.08
0.54 0.68
36
0.08
0.04
0.21
0.46
37 38 39 40 41 42
0.12 0 0.04 0.04 0.12 0.08
0.16 0.17 0.08 0.08 0.08 0
0.28 0.17 0.28 0.16 0.16 0.48
0.24 0.33 0.4 0.48 0.24 0.2
Equipment 43 Falling-weight deflectometer 44 Straddling painters 45 Maintainers on gravel roads 46 Cold-mix patchwork 47 Friction testing 48 Media trucks Trucks carrying rock/ 49 aggregate 50 Boom trucks 51 Pick-up trucks 52 53 54 Street sweepers/street cleaners Jet vac Paint carts (hauled on trailers)
0.04 0.04 0 0.09 0.17 0.3 0.13 0.13 0.17 0.13 0.14 0.13
0.13 0.13 0.26 0.22 0.09 0.09 0.13 0.17 0.39 0.22 0.14 0.13
0.17 0.26 0.3 0.39 0.26 0.22 0.26 0.35 0.17 0.17 0.36 0.3
0.17 0.39 0.04 0.17 0.04 0.17 0.26 0.17 0.13 0.26 0.09 0.17
47
Probable
Unlikely
Neutral
Frequency Very Probable 0.26 0.14 0.17 0.04 0.09 0.09 0.43 0.23 0.04 0.05 0.23 Very Unlikely Weighted Average of Likelihood of Occurrence 0.2600 0.2093 0.2313 0.1913 0.1307 0.1840 0.2467 0.2120 0.1680 0.1907 0.2493
ID 55 56 57 Other 58 59 60 61 62 63 64 65 Lack of coordination with municipalities Work done under full closure Lack of coordination between state and local agencies Lack of work safety and training programs Absence of train-the-trainers philosophy Lack of coordination between DOT and utilities regarding control of ROW Improper third-party interaction Not imposing speed limit fines on public Absence of proper signage near work zone Absence of fluorescent diamond signs Not using lights/blinkers in work zone
0.04 0.09 0.04
0 0.05 0.04
0.04 0.27 0.26
0.61 0.36 0.43
0.04 0.39 0.04 0.09 0.05 0.13 0 0
0.13 0.48 0.17 0 0.14 0.13 0.14 0.05
0.39 0 0.35 0.26 0.14 0.35 0.23 0.23
0.3 0.04 0.22 0.17 0.32 0.22 0.41 0.45
Analysis of Severity and Ranking of the Factors The severity is analyzed by calculating a weighted average of the five levels of severity. The weight is assigned to the factors based on their importance and level of severity as follows: ? ? ? ? ? No Loss = 1 Potential Property Damage = 2 Minor Property Damage and/or Minor Injuries = 3 Major Property Damage and/or Major Injuries = 4 Catastrophic Loss/Fatality = 5
48
Probable
Unlikely
Neutral
The weighting is used to create a severity index score that can be used to rank the factors according to the associated severity of the crashes. The weighted average of the severity is calculated in the following way: Weighted average of severity (FWD Structural Testing on Pavement and Subgrade) = (0.06 × 1 + 0.16 × 2 + 0.22 × 3 + 0.22 × 4 + 0.0 × 5) ÷ 15 = 0.1280 Figure 12 shows the distribution of the factors graphically according to the weighted average of the severity levels. According to this distribution, the factors are ranked on a Likert scale from 1 to 5 (with 1 being the least severe and 5 being the most severe): ? ? ? ? ? Less than 0.1 = 1 0.10 - 0.15 = 2 0.15 - 0.20 = 3 0.20 - 0.25 = 4 0.25 - 0.30 = 5
Based on the distribution of the factors according to the severity levels as shown in Figure 12 and the categories as defined above, the factors were ranked according to severity, which is shown in Table 15.
49
Figure 12. Distribution of the severity levels of the factors (crash database) present in all crashes involving intermittent and moving work zones and work on the shoulders and median
50
Table 15. Ranking of the factors according to severity Activity Flagger operations Mowing Straddling painting (centerline painting) Offset painting (edge-line painting) on four-lane divided highway Offset painting (edge-line painting) on two-lane two-way traffic roadway Pavement markings Crack filling/patch work Replacing/repairing the signals and signage Loading/unloading material for maintenance operations on four-lane divided highway Loading /unloading material for maintenance operations on two-lane two-way road Repair, maintenance, and installation of guardrails, cable rails, and barrier rails on two-lane two-way road Repair, maintenance, and installation of guardrails, cable rails, and barrier rails on four-lane divided highway Repair, maintenance, and installation of centerline guardrails, cable rails, and barrier rails on four-lane divided traffic roadway Ingress and egress from construction site FWD structural testing on pavement and subgrade Movement of street sweeper/street cleaner Core drilling on pavements Manual condition surveys for pavement section Bridges and culvert repair and inspection Curb and surface repairs Shoulder grading Maintenance of sanitary and storm sewer and water main Ditch cleaning Cleaning storm sewer intakes and structures Survey work Electric/power system maintenance and street lighting Snow removal Ride quality testing on pavement or bridge surface Environment Nighttime operations Improper signs and signage at ramps and roadway intersections near work zones Work zones on roads in hilly areas Peak traffic hours Fog and mist Pavement markings at intersections at nighttime Pavement markings at intersections at daytime Severity 4 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 2 2 1 Severity 4 4 4 4 4 3 3
51
Lack of knowledge about variable peak traffic time in local regions near work zone (e.g., variable travel patterns near institutions like the Iowa DOT, University, and Animal Disease Lab in Ames, Iowa) Work near railway crossings Clearing roadway for emergency vehicles Unforeseen weather conditions Presence of small towns or schools nearby Different rules in shared jurisdictions Special events such as parades, races, and fairs in local cities and towns Equipment Absence of proper signage near the work zone Not using lights/blinkers in the work zone Absence of fluorescent diamond signs Straddling painters Trucks carrying rock/aggregate Cold-mix patchwork Boom trucks Media trucks Pick-up trucks Street sweepers/street cleaners Jet vac Paint carts (hauled on trailers) Falling-weight deflectometer Maintainers on gravel roads Friction testing Other Lack of work safety and training programs Not imposing speed limit fines on public Absence of train-the-trainers philosophy Lack of coordination with municipalities Work done under full closure Lack of coordination between state and local agencies Lack of coordination between DOT and utilities regarding control of ROW Improper third-party interaction Analysis of Frequency
3 3 3 3 2 2 2 Severity 4 4 3 3 3 3 3 2 2 2 2 2 1 1 1 Severity 4 4 3 2 2 2 2 2
Weighted average of the frequency of occurrence of the different factors is also calculated to rank the factors on the same scale according to their likelihood of occurrence. The weighted average of the frequency/likelihood of occurrence is calculated as follows: Weighted average of frequency (FWD Structural Testing on Pavement and Subgrade) = (0.12 × 1 + 0.12 × 2 + 0.28 × 3 + 0.12 × 4 + 0.0 × 5) ÷ 15 = 0.1120
52
Figure 13 shows the distribution of the factors graphically according to the weighted frequency. According to this distribution, the factors are ranked on a Likert scale from 1 to 5 (with 1 being the least frequent and 5 being the most frequent): ? ? ? ? ? Less than 0.1 = 1 0.10 - 0.15 = 2 0.15 - 0.20 = 3 0.20 - 0.25 = 4 0.25 - 0.30 = 5
Based on the distribution of the factors according to the frequencies shown in Figure 13 and the categories defined above, the factors are ranked according to frequency as shown in Table 16.
53
Figure 13. Distribution of the percentage frequency of the factors (crash database) present in all crashes involving intermittent and moving work zones and work on the shoulders and median
54
Table 16. Ranking of the factors according to frequency Activity Ingress and egress from construction site Straddling painting (centerline painting) Offset painting (edge-line painting) on four-lane divided highway Offset painting (edge-line painting) on two-lane two-way traffic roadway Pavement markings Crack filling/patch work Curb and surface repairs Flagger operations Replacing/repairing the signals and signage Loading /unloading material for maintenance operations on four-lane divided highway Loading /unloading material for maintenance operations on two-lane two-way road Repair, maintenance, and installation of guardrails, cable rails, and barrier rails on four-lane divided highway Repair, maintenance, and installation of guardrails, cable rails, and barrier rails on two-way two-lane road Repair, maintenance, and installation of centerline guardrails, cable rails, and barrier rails on four-lane divided traffic roadway Snow removal FWD structural testing on pavement and subgrade Ride quality testing on pavement or bridge surface Core drilling on pavements Manual condition surveys for pavement section Bridges and culvert repair and inspection Mowing Movement of street sweeper/street cleaner Shoulder grading Cleaning storm sewer intakes and structures Survey work Electric/power system maintenance and street lighting Maintenance of sanitary and storm sewer and water main Ditch cleaning Environment Nighttime operations Peak traffic hours Improper signs and signage at ramps and roadway intersections near work zones Pavement markings at intersections at nighttime Work zones on roads in hilly areas Lack of knowledge about variable peak traffic time in local regions near work zone (e.g., variable travel patterns near institutions like the Iowa DOT, University, and Animal Disease Lab in Ames, Iowa) Clearing roadway for emergency vehicles Frequency 4 3 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 2 1 Frequency 5 5 4 4 4 4 4
55
Unforeseen weather conditions Fog and mist Presence of small towns or schools nearby Pavement markings at intersections at daytime Work near railway crossings Different rules in shared jurisdictions Special events such as parades, races, and fairs in local cities and towns Equipment Absence of proper signage near the work zone Absence of fluorescent diamond signs Not using lights/blinkers in the work zone Straddling painters Cold-mix patchwork Trucks carrying rock/aggregate Maintainers on gravel roads Media trucks Boom trucks Pick-up trucks Street sweepers/street cleaners Jet vac Paint carts (hauled on trailers) Falling-weight deflectometer Friction testing Other Lack of work safety and training programs Absence of train-the-trainers philosophy Not imposing speed limit fines on public Lack of coordination with municipalities Lack of coordination between state and local agencies Lack of coordination between DOT and utilities regarding control of ROWs Improper third-party interaction Work done under full closure Risk Rating of the Factors
4 4 3 3 3 3 3 Frequency 5 4 4 3 3 3 2 2 2 2 2 2 2 1 1 Frequency 4 4 4 3 3 3 3 2
Similar to crash data analysis, the risk assessment value of the hazards/factors identified in the survey is calculated by multiplying the frequency rating and the severity rating of the hazards. Thereby, the risk assessment value of the factors ranges from 1 (1×1) to 25 (5×5), which is the same as that of the risk assessment value range obtained from the crash data analysis. Thus, the same Integrated Risk Management Model can be used to assess the identified risks obtained from both the crash data and the survey data as shown in Table 17.
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Table 17. Ranking of the factors according to risk assessment value Activities Flagger operations Ingress and egress from construction site Straddling painting (centerline painting) Offset painting (edge-line painting) on four-lane divided highway Offset painting (edge-line painting) on two-lane two-way traffic roadway Pavement markings Crack filling/patch work Replacing/repairing the signals and signage Loading /unloading material for maintenance operations on four-lane divided highway Loading /unloading material for maintenance operations on two-lane two-way road Repair, maintenance, and installation of guardrails, cable rails, and barrier rails on four-lane divided highway Repair, maintenance, and installation of guardrails, cable rails, and barrier rails on two-way two-lane road) Repair, maintenance, and installation of centerline guardrails, cable rails, and barrier rails on four-lane divided traffic roadway) Mowing Curb and surface repairs Snow removal FWD structural testing on pavement and subgrade Shoulder grading Core drilling on pavements Manual condition surveys for pavement section Bridges and culvert repair and inspection Maintenance of sanitary and storm sewer and water main Movement of street sweeper/street cleaner Cleaning storm sewer intakes and structures Survey work Electric/power system maintenance and street lighting Ride quality testing on pavement or bridge surface Ditch cleaning Environment Night time operations Peak traffic hours Improper signs and signage at ramps and roadway intersections near work zones 57 Frequency 1 3 4 3 3 3 3 3 3 3 3 3 3 3 2 3 3 2 2 2 2 2 2 2 2 2 2 2 1 Frequency 1 5 5 4 Severity 2 4 3 3 3 3 3 3 3 3 3 3 3 3 3 2 2 2 2 2 2 2 2 2 2 2 2 1 2 Severity 2 4 4 4 Risk Value 1×2 12 12 9 9 9 9 9 9 9 9 9 9 9 6 6 6 4 4 4 4 4 4 4 4 4 4 2 2 Risk Value 1×2 20 20 16
Work zones on roads in hilly areas Fog and mist Pavement markings at intersections (at nighttime) Lack of knowledge about variable peak traffic time in local regions near work zone (e.g., variable travel patterns near institutions like the Iowa DOT, University, and Animal Disease Lab in Ames, Iowa) Clearing roadway for emergency vehicles Unforeseen weather conditions Pavement markings at intersections at daytime Work near railway crossings Presence of small towns or schools nearby Different rules in shared jurisdictions Special events such as parades, races, and fairs in local cities and towns Equipment Absence of proper signage near the work zone Not using lights/blinkers in the work zone Absence of fluorescent diamond signs Straddling painters Cold-mix patchwork Trucks carrying rock/aggregate Boom trucks Media trucks Pick-up trucks Street sweepers/street cleaners Jet vac Paint carts (hauled on trailers) Maintainers on gravel roads Friction testing Falling-weight deflectometer Other Not imposing speed limit fines on public Lack of work safety and training programs Absence of train-the-trainers philosophy Lack of coordination with municipalities Lack of coordination between state and local agencies Lack of coordination between DOT and utilities regarding control of ROWs Improper third-party interaction Work done under full closure
4 4 4 4 4 4 3 3 3 3 3 Frequency 1 5 4 4 3 3 3 2 2 2 2 2 2 2 1 1 Frequency 1 4 4 4 3 3 3 3 2
4 4 3 3 3 3 3 3 2 2 2 Severity 2 4 4 3 3 3 3 3 2 2 2 2 2 1 1 1 Severity 2 4 4 3 2 2 2 2 2
16 16 12 12 12 12 9 9 6 6 6 Risk Value 1×2 20 16 12 9 9 9 6 4 4 4 4 4 2 1 1 Risk Value 1×2 16 16 12 6 6 6 6 4
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The results are analyzed and explained in the final section of this report (Discussion and Implications of the Results.) Development of the Integrated Risk Management Model A risk matrix was developed as part of the risk assessment process as a metric representing the association of significant factors to severity and frequency of crashes. In the development of the Integrated Risk Management Model, the significant factors were termed hazards to be consistent with prior research on risk. A hazard is a condition (e.g., blowing snow or excessive speed) that contributes to a loss event, either as the proximate cause of the loss or as a contributing factor. A risk of loss can be represented as the total of each of the hazards (factor) that contribute to it. The risk associated with any particular hazard, H, can be defined as its probability or likelihood of occurrence (i.e., the frequency), p, multiplied by its severity, c. Stated simply, the risk associated with any single hazard is the product of how likely it is to happen and how bad it would be if it did happen, as represented in the following equation. Hazard = PH × CH The total risk, R, of a loss event, e, is the sum of the n potential hazards that would result in that event:
The severity of the factors is obtained from the weighted average of the marginal effects of the statistical model, and, the frequency or likelihood of occurrence of the factors is obtained from the descriptive statistics. The best tool to assess the risk of the hazards in such a scenario is to develop a risk assessment matrix. A risk assessment matrix is a two-dimensional representation of the frequency or likelihood of occurrence of the hazards on one scale (frequency scale) and the severity or consequence of those hazards on the other scale (severity scale). The frequency scale is on the vertical axis and the severity scale is on the horizontal axis. Both the scales are marked from 1 to 5. Thus, the risk assessment matrix (Figure 14) measures the risk of the hazards on a scale of 1 (1×1) to 25 (5×5).
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5 5
10
15
20
25
1 to 3
Negligible Risk Potential
4 Frequency 4
8
12
16
20
4 to 5
Marginal Risk Potential
3 3
6
9
12
15
6 to 9
Moderate Risk Potential
2 2
4
6
8
10
10 to 12
Critical Risk Potential Catastrophic Risk Potential
1 1 1
2 2
3 3 Severity
4 4
5 5
15 to 25
Figure 14. Risk assessment matrix As shown, this scale is categorized into five levels, depending on the magnitude or overall effect of the risk: ? ? ? ? ? Negligible Risk Potential – Risk value ranging from 1 to 3 Marginal Risk Potential – Risk value ranging from 4 to 5 Moderate Risk Potential – Risk value ranging from 6 to 9 Critical Risk Potential – Risk value ranging from 10 to 12 Catastrophic Risk Potential – Risk value ranging from 15 to 25
The color-coded risk assessment matrix is a very useful technique to determine the potential risk of the hazards already identified from the crash database analysis. This matrix should be used in conjunction with Table 12 and Table 17, which contain the identified significant factors generated from the Iowa DOT statewide crash data analysis along with the combined hazard value and also the factors identified from the survey data analysis, respectively. Any hazard present in a risk event can be assessed in the following way: Say, for example, the factor BETAWWRK, from the crash database, has a hazard value of 8, which means the location between the advance warning sign and work area bears a moderate risk potential and a crash occurring within this region would likely be a moderately severe crash. On the other hand, the factor WTHWRKZN has a hazard value of 10, which means the location within or adjacent to the work activity bears critical risk potential and the crashes occurring within this zone is more likely to be severe than the other location. Hence, the second location needs to be closely monitored and proper traffic control measures need to be taken to avoid crashes within this location.
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The risk assessment matrix helps in prioritizing the different hazards and thereby helps in planning risk mitigation strategies. Given that a “typical” crash is assumed to have both the frequency and severity ranked as 3, the combined value of 9 (3×3) marked the boundary for moderate risk potential. Anything greater than this value was considered as having critical or catastrophic risk potential.
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DISCUSSION OF KEY FINDINGS Crash Data Analysis Six factors were assessed with a hazard value greater than 9 as follows: ? ? ? ? ? ? Interstate route US route Municipal route Passenger vehicle Vision not obscured by moving vehicles or frosted windows/windshield, blowing snow, or fog/smoke/dust Region located within or adjacent to the work activity
The researchers found that the routes of travel are extremely critical from the overall risk point of view. According to the methodology of this research, these hazards should be determined to have the top-most priority while planning for mitigation strategies. Some reasons for significance of the routes of travel are likely higher speeds on interstates and US highways and inadequate/improper traffic control systems not coordinated with the actual location of the mobile operations. The analysis shows interesting results in terms of location of the crash. It describes the region located within or adjacent to the work activity bears critical or catastrophic risk potential and severe crashes are more likely to occur within this zone. This indicates that proper traffic control measures may not be in use near or within the mobile work zones, or that traffic control may be keeping pace with the moving operations. Proper safety rules need to be followed in those regions. In addition to the above mentioned factors, those hazards having a value of 5 on either the severity scale or the frequency scale need attention. Four factors were assessed with a value of 5 in the severity scale as follows: ? ? ? ? US route Secondary route Municipal route Iowa route
On these routes, the crashes that are occurring are mostly severe crashes.
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Three factors are assessed with a value of 5 in the frequency scale as follows: ? ? ? Vision not obscured by moving vehicles or frosted windows/windshield, blowing snow, or fog/smoke/dust Interstate route Region located within or adjacent to the work activity
Most of the crashes related to the maintenance and mobile operations work zone occur when vision is not obscured by moving vehicles or frosted windows/windshield, blowing snow, or fog/smoke/dust. This is because, if the vision is not obscured by any obstruction, most likely the vehicles will drive at a higher speed. If coming upon a mobile work zone like lane painting or guardrail repairs, it may then happen that the vehicles are unable to control their speed and end up traveling into the work zone causing a crash. The Interstate route is also another important factor in terms of frequency of crashes taking place. About 63 percent of the crashes take place on the interstates. Because crashes on virtually all types of routes were determined to be severe by the model, the researchers suspected the model may be over-specified in terms of route types. Therefore, the model was re-run (model 2) eliminating state and local routes from the analysis. The most interesting change is in the severity result related to the Interstate route, which went down from a severity ranking of 3 in the first model to a severity ranking of 1 in model 2. The frequency ranking (of 5) remained the same. When state and municipal routes were deleted from the final model, the Interstate route had a negative marginal effect instead of a high positive value, as was the case in the initial model. This change suggests that a crash on an interstate is actually more likely to be a PDO crash and contrasts with the results from the initial model, which suggested that crashes on all routes were likely to be severe. Thus, the initial observation that higher speed limits on interstates were causing more severe work-zone crashes appears to be in doubt. An alternative explanation is that, given the study focused on work-zone crashes only, where speeds are reduced, and variation in travel speeds are likely to be minimized, interstates are actually safer due to their superior design parameters compared to other routes and are also better maintained, generally speaking. Interstate mobile work zones almost always maintain a minimum of two divided lanes in each direction, whereas, other routes are frequently head-tohead traffic. In other words, the interstates provide more space (in terms of number of lanes) for the vehicles to pass by the mobile work zone than that of other routes. Similarly, the region located within or adjacent to the mobile work activity is critical in terms of the frequency of the crashes. Most of the crashes are likely to occur within or adjacent to the work activity, indicating that proper traffic control systems and safety rules are important.
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Validation Survey Data Analysis In the validation survey, factors (or hazards) were categorized as follows: ? ? ? ? Activity Environment Equipment Other
The factors within each category are ranked in the descending order of the magnitude of the severity, frequency, and risk assessment value in Tables 14, 16 and 17, respectively. The Integrated Risk Management Model helps in prioritizing the different identified factors (or hazards) when used in conjunction with the risk assessment values of the factors as shown in Table 17. The hazards with a risk assessment value (i.e., the combined value of severity and frequency) greater than 9 (i.e., hazards bearing critical or catastrophic risk potential) are as follows: Activity ? Flagger operations ? Ingress and egress from construction site Environment ? Nighttime operations ? Peak traffic hours ? Improper signs and signage at ramps and roadway intersections near work zones ? Work zones on roads in hilly areas ? Fog and mist ? Pavement markings at intersections at nighttime ? Lack of knowledge about variable peak traffic time in local regions near work zone (e.g., variable travel patterns near institutions like the Iowa DOT, University, and Animal Disease Lab in Ames, Iowa) ? Clearing roadway for emergency vehicles ? Unforeseen weather conditions Equipment ? Absence of proper signage near the work zone ? Not using lights/blinkers in the work zone ? Absence of fluorescent diamond signs Other ? Not imposing speed limit fines on public ? Lack of Work safety and training programs ? Absence of train-the-trainers philosophy
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The nine hazards that are in the red zone with catastrophic risk potential (among all the factors and under all the categories) are as follows: ? ? ? ? ? ? ? ? ? Nighttime operations Peak traffic hours Absence of proper signage near the work zone Improper signs and signage at ramps and roadway intersections near work zones Work zones on roads in hilly areas Fog and mist Not using lights/blinkers in the work zone Not imposing speed limit fines on public Lack of work-safety and training programs
According to the validation survey results, the hazards mentioned above are most likely to cause very serious (or catastrophic) crashes due to the operations and maintenance activities. Of the 65 hazards that were identified from the expert panel discussion, only three hazards have been assessed in the survey with a frequency score of 5: ? ? ? Nighttime operations Peak traffic hours Absence of proper signage near the work zone
None of the hazards scored 5 for severity. The survey respondents appear to perceive that most of the crashes due to O/M activities occur when the operations are carried out during nighttime and during peak traffic hours. Absence of proper signage near the work zone is perceived as another major cause of crashes. The potential hazards related to crash risks during O/M activities were identified through expert panel discussions and literature reviews, analyzed through statistical modeling of quantitative crash data and determination of perceptual data obtained through a national survey, and assessed by developing an integrated risk model and risk value assignments.
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Identification of Risk Mitigation Strategies The final step in the research study was to develop relevant mitigation strategies for potential adoption in mobile work zones. The results of the expert-panel brainstorming workshop, follow-up in-depth interviews with three members of the panel, analysis of the crash database, and perceptions from a national survey suggest the following risk mitigation strategies may be helpful in reducing the severity and frequency of crashes in mobile work zones associated with O/M activities. 1. Revise and integrate the Iowa DOT Instructional Memorandums (IM), Traffic and Safety Manual, and Standard Road Plans – TC Series (traffic control diagrams) and related notes to provide clear, comprehensive, and easily-accessible guidance on placement of traffic control measures for mobile work zones. 2. Consider expanding traffic-control options to include proven technologies such as the Balsi Beam, portable rumble strips, blue strobe lights, and other innovations. Traffic-control specifications and associated allocation of risk between contractors and state/local agencies would also need to be revised to encourage adoption of new traffic-control measures. This is an area where a follow-up study would prove beneficial. 3. Investigate new delivery technologies (such as Skype, webinars, and remote conferencing) to allow for improved training within the flattened structure of the Iowa DOT. The training should include both formal programs for centralized functions and informal weekly programs for supervisory personnel to discuss issues with field crews. The Local Technical Assistance Program (LTAP) at the Institute for Transportation (InTrans) may be of assistance in developing such a safety-training program. The safety-training program will be particularly helpful for new and temporary employees working in mobile operations. 4. Written manuals and training programs should focus on the importance of worker and equipment visibility and advance warning systems, especially in high-speed environments (interstates and US highways) and those where drivers may be distracted more easily by pedestrians, traffic signals, bicyclists, etc., such as municipal streets. 5. Schedule Best Practices meetings regularly within divisions. Encourage shop management to meet with division managers and other shop managers to discuss best practices that are discovered in the field, especially when it comes to safety. Division managers should also hold meetings periodically to encourage this type of information sharing. The alternative delivery technologies mentioned above may also be helpful in disseminating best practices. 6. Certain environments should be reviewed to ensure that the minimum number of workers and vehicles are used in the traffic-control system. Specifically, two lane two-way highways, work at railroads and other utility sites, overhead work, and work on bridges are likely highrisk environments where additional vehicles and workers increase the risk of crashes. The
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value of impact attenuators should be researched to determine the safety benefits of such equipment. The analysis of the crash database did not find any reports of impact attenuators associated with mobile work-zone crashes. 7. Policies and safety training programs should emphasize the need for locating traffic controls at the appropriate distance from the work site to allow for driver reactions, and traffic controls should be moved at the same pace as the mobile operations whenever possible. Research Limitations The limitations of this research study are as follows. ? All of the factors/hazards that were studied in this research could not be described by the crash database variables queried. Representative variables were selected and analyzed from the crash database, which indirectly explained the effect of the required variables/factors/hazards. The data entered on the responding officer’s report does not always match the variable of interest. The crash data were drawn from the Iowa crash database, but the survey and literature review was national in scope. This made the research study somewhat biased. To get a good sample size, crash data from the last 10 years (2001 through 2010) were analyzed. This may have included information about several crashes that occurred after changes in work-zone signage practices and other infrastructure development. The response rate for the validation survey was low. Because of the sample size, no statistical analysis could be performed.
?
?
?
Implementation Readiness The possible mitigation strategies developed as a result of this research are not field-tested, as it was out of the scope of this research project. If further research on the implementation ideas is needed, a separate research study can be conducted focusing on the implementation of the riskmitigation techniques found as a result of this study. Testing may include evaluation of the riskmitigation strategies in simulators or actual field situations to determine effectiveness.
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Implementation Benefits The research findings are intended to provide a process map or guidebook outline for use by the Iowa DOT, Iowa county engineers, and municipal transportation agencies to assess the risk potential of various O/M activities and develop team-based risk-mitigation strategies. The primary benefits of this research are the reduced risk of injury, fatality, and property damage for O/M workers and the traveling public. The research results can be implemented by the Iowa DOT staff, county engineers, municipal transportation directors, and any other transportation professionals responsible for O/M activities, including field personnel. The results can also be used as a standard process for identifying highest-risk O/M activities and developing mitigation strategies to reduce those risks. However, it should be noted that the riskmitigation processes developed and envisioned in this research are highly inclusive, involving state, local, and regional professionals from both field and office positions. Intuitively, any process that decreases risk should improve worker safety, lower agency costs, improve service to the traveling public, and lead to more-efficient procedures over the long-term, although these specific performance benefits are not assessed directly as part of this research project.
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REFERENCES Blincoe, L., A. Seay, E. Zaloshnja, T. Miller, E. Romano, S. Luchter, and R. Spicer. 2002. The Economic Impact of Motor Vehicle Crashes: 2000. National Highway Traffic Safety Administration (NHTSA). Report No. DOT HS 809 446. May 2002. Goodwin, L. C. 2003. Best Practices for Road Weather Management. Weather. May 2003. Iowa DOT. 2001. Investigating Officer’s Accident Reporting Guide. Iowa Department of Transportation. Motor Vehicle Division. Office of Driver Services. January 2001. (Code sheet available at:http://www.iowadot.gov/mvd/ods/accidents.htm.) Juni, E., T. M. Adams, and D. Sokolowski. 2008. Relating Cost to Condition in Routine Highway Maintenance. Transportation Research Record. Washington, DC: Transportation Research Board. 2044(1):3-10. doi: 10.3141/2044-01. Moriarty, K. D., J. Collura, M. Knodler, D. Ni, and K. Heaslip. 2008. Using Simulation Models to Assess the Impacts of Highway Work Zone Strategies: Case Studies along Interstate Highways in Massachusetts and Rhode Island. TRB 2008 Annual Meeting. Washington, DC: Transportation Research Board. CD-ROM submission. Retrieved fromhttp://www.workzonesafety.org/files/documents/database_documents/Publication9955.pd f. Paaswell, R. E., R. F. Baker, and N. M. Rouphail. 2006. Identification of Traffic Control Devices for Mobile and Short Duration Work Operations. FHWA-NJ-2006-006. Accessed March 20, 2011.http://ntl.bts.gov/lib/25000/25000/25088/Final_report-Work_Zones_DevicesUTRC.doc. Pisano, P .A., L. Goodwin, and A. Stern. 2002. Surface Transportation Safety and Operations: The Impacts of Weather within the Context of Climate Change. Weather. pp. 1-20. Retrieved fromhttp://climate.dot.gov/documents/workshop1002/pisano.pdf. Pisano, P. A., L. C. Goodwin, and M. A. Rossetti. 2008. U.S. Highway Crashes in Adverse Road Weather Conditions. Most. pp. 1-15. Retrieved fromhttp://ams.confex.com/ams/pdfpapers/133554.pdf. Qin, X., D. Noyce, C. Lee, and J. Kinar. 2006. Snowstorm Event-Based Crash Analysis. Transportation Research Record. Washington, DC: Transportation Research Board. 1948(1):135-141. doi: 10.3141/1948-15. Shane, J. S., K. C. Strong, and D. Enz. 2009. Construction Project Administration and Management for Mitigating Work Zone Crashes and Fatalities: An Integrated Risk Management Model. Ames, Iowa: Midwest Transportation Consortium. Iowa State University.http://www.intrans.iastate.edu/mtc/researchdetail.cfm?projectID=1216322435 Shi, X. 2010. Winter Road Maintenance: Best Practices, Emerging Challenges, and Research Needs. Journal of Public Works and Infrastructure. 2(4):318-326. Sorenson J., E. Terry, and D. Mathis. 1998. Maintaining the Customer-Driven Highway. Public Roads. 62(3):45. Steele, D. A, and W. R. Vavrik. 2010. Improving the Safety of Mobile Lane Closures. Transportation Research Record. Washington, DC: Transportation Research Board. 2169(1):11-20. doi: 10.3141/2169-02. Sun, D., P. Ravoola, M. A. Faruqi, B. R. Ulman, and N. D. Trout. 2011. Assessment of Need and Feasibility of Truck-Mounted Changeable Message Signs (CMS) for Scheduled and Unscheduled Operations. FHWA/TX-TECHNICAL REPORT #11/0-6167-1.
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Washington S., M. Karlaftis, and F. Mannering. 2010. Statistical and Econometric Methods for Transportation Data Analysis. 2nd Edition. pp. 349.
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APPENDIX A. LIGHTING STUDIES This appendix includes a summary of three major service vehicle lighting studies with relevance to our study for risk mitigation in mobile and maintenance operations. Study 1: Effect of Warning Lamps on Pedestrian Visibility and Driver Behavior University of Michigan, Transportation Research Institute This study examined how warning lighting has an adverse effect on drivers’ ability to see workers outside of their vehicles. The three areas of the study cover nighttime glare from warning lamps, effects on driving performance, and nighttime photometry. The study was done on a closed course track with a mannequin set up near a vehicle that was at a standstill and a panel of warning lights set to various settings, where drivers were asked to identify at exactly what point they were able to see the mannequin. The horizontal passing distance between the mobile car and stationary car was also measured in each trial. The major findings in this study showed that the only major deterrent from the driver’s ability to see the mannequin standing near the parked vehicle was the level of reflective clothing that the mannequin was wearing. Study 2: Recommendations for Service Equipment Warning Lights Texas Department of Transportation (TxDOT) This study was part of a larger research project about maintenance activities. According to TxDOT operation manuals, blue lights are to be used by maintenance vehicles that travel less than 5 mph slower than operating traffic in a travel lane or 30 mph less than operating traffic when not in a traveling lane. Results show people have learned a hierarchy with regards to flashing warning lights. Yellow conveys the least degree of danger, a combination of yellow and blue conveys the second least, a combination of blue and red represents the highest perception of danger to drivers, and red is perceived to represent more danger than any of the other lights individually. People also believe there is less of a need to slow down when yellow warning lights are used compared to other colors. This study also reviewed which types of vehicles drivers associate with different color of warning lights. Yellow lights are associated with the most basic service vehicles, including maintenance and motorist-assistance vehicles, such as tow trucks. People most associated blue and red lights with police and law enforcement vehicles. Red warning lights were most likely to be associated with ambulances, fire trucks, and emergency-response vehicles.
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A set of warning lights was placed on a roadway to monitor the average speed of vehicles as they related to the color of warning lights. The only two lights that were compared in this study were yellow and blue. The color combination of yellow and blue showed the only statistically significant speed difference in this study. The blue or yellow lights alone did not show any significance in speed reduction. This study also explored the effect of warning light colors on brake light activations. The only lighting set-up that did not show a statistically significant increase in brake applications was yellow only. The researchers believed that this portion of the study was the most important and showed the best indicators of how people actually respond to warning lights. They also stated evidence of an incremental benefit to implement a combination of blue and yellow lights rather than yellow alone. Study 3: LED Warning Lights for DOT Vehicles CTC and Associates, Wisconsin Department of Transportation (WisDOT) Studies on the use of LED lighting have come with mixed results from several different applications. Wiring these LED systems, when compared to standard strobe lights, is cheaper. However, the overall startup has higher associated costs. Differing colors have presented cost issues as well. LEDs present far fewer maintenance problems over the long term so, in many cases, LEDs have been less expensive overall. LEDs have been found to have a running life under field conditions of around 100,000 hours and only draw about 10 percent of the amperage of normal incandescent lighting systems. LEDs are able to turn on and off much more quickly so their ability to “punch” signals rather than turning on from a slow glow is better. LEDs will likely be an extremely economic alternative to the systems in use currently. Another advantage of the LED’s ability to turn on faster is the capability for trailing drivers to see a vehicle that is breaking in front of them. According to the study, the extra time saved in signaling presents one extra car length of room for drivers to react at 65 mph. When retrofitting fleets, it is important to consider how many phases it will take to equip all of the vehicles. It can be a problem if too many vehicles are taken out of commission at one time and take away from the day-to-day duties of the fleet. For example, it would be most economical to fit snowplows during the summer when the equipment is not being used.
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APPENDIX B. EXPERT PANEL SUMMARY REPORTS TAC Kick-Off Meeting Moving operations is a common term used for construction activities that involve mobile work zones, such as painting and pavement marking, guardrail replacement, repair of the signage, pavement inspection, structural testing, and so forth. These activities fall under the general heading of operations and maintenance (O/M). The basic objective of this research is to develop an integrated risk modeling approach, which could be used to reduce the frequency and intensity of loss events (property damage, personal injury, fatality, etc.) during highway O/M activities. The first task of the research plan is to identify the current O/M processes used by state, county, and local agencies. To begin this task, a meeting was held at the Institute for Transportation (InTrans) with the expert technical advisory committee (TAC) on December 10, 2010 to identify those current O/M processes. During the panel discussion/brainstorming workshop, identified O/M activities were classified into four broad categories per the activities, environments, and tools/equipment used and the different relationships involved with O/M functions. The potential risk factors involved in the categories that were identified during this meeting include the following: ? ? ? ? ? ? ? ? ? Traffic level/congestion Number of roadway lanes Posted speed limit Inadequate/improper signage Inadequate/improper vehicle lighting and marking Insufficient worker training Proximity of obstructions (equipment) to traveled roadway Weather (condition of road surface, visibility, etc.) Work under traffic (inadequate separation or lack of detours/lane shifts)
Moving operations involve mainly the following four types of work zones: ? ? ? ? Short-term work zones Intermediate work zones Overnight work zones Work zones within 15 ft of the moving traffic
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Current O/M Processes and Practices A detailed, edited report of current O/M processes and practices follows. A. Activity 1. Material testing: The methods generally used for roadway and pavement testing are as follows. Falling-weight deflectometer (FWD) structural testing - A non-destructive test performed to evaluate the strength properties of the pavement and subgrade layers. Information is used in the pavement management system as well as in the pavement design process. The equipment stops in the lane and the loading instrument is lowered to contact the pavement. Ride-quality testing – A non-destructive test conducted with either a 25 ft profilograph or a lightweight inertial profiler to measure the ride quality of a pavement or bridge surface. The profilograph is pushed at about 3 mph. A lightweight profiler operates at 10 to 20 mph. Core drilling – A destructive process used to drill and cut out a pavement core for laboratory analysis. The drill is truck mounted. The truck stops in the lane and the drill is lowered to contact the pavement. Manual condition surveys – A non-destructive process to obtain condition data for a pavement section. The FWD and core drilling operations involve stopping in the lane of travel. Depending on the distance between stops or the length of time stopped, these operations will be either a moving operation or a temporary lane closure. Once the test is taken or the core is drilled, the equipment can move to the shoulder to allow traffic to proceed. Ride-quality testing involves a machine/equipment mounted on a moving vehicle and thus belongs to the moving operations work zone. The testing is continuous and the equipment must stay in the lane and at test speed for the duration of the test section. The condition survey process is done from the shoulder when there is a wide enough shoulder. Staff may have to enter the lane to take measurements, normally at traffic gaps. These testing operations can often block the main roadway and disrupt/slow down the normal flow of the traffic. The risks posed by these types of operations include, but are not limited to: distract the drivers’ attention, force the vehicles to move toward the roadway edge, loss of control, and infringe on sidewalk or bike path.
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2. Bridges and culvert repair and inspection: These types of operations are also moving work-zone operations, as most of the inspection activities are of short duration. These activities also pose risks including, but not limited to, blocks the main roadway, slows down the traffic, distracts the drivers’ attention toward the work zone, forces vehicles to move adjacent to the testing equipment, forces vehicles to move toward the roadway edge, loss of control, and collision with guardrails of the bridges or the culverts. Therefore, these types of inspection activities also pose risk. 3. Mowing: This activity doesn’t typically affect the traffic but would be considered a work zone when it occurs within 15 ft of the roadway. However, while mowing a sloped embankment on the side of a pavement or a roadway, the equipment may block the traffic to some extent and the same risks as mentioned above may occur. 4. Movement of street sweeper: A street sweeper or street cleaner refers to a variety of mobile equipment that cleans streets, usually in an urban area. This type of activity slows down traffic to less than the normal traffic speed and may distract drivers’ attention. 5. Painting: Painting constitutes the major portion of moving O/M activities. About 90 percent of the painting activities belong to the moving operation category. Painting has a big impact on traffic. It is extremely dynamic and depends on several factors. Roadway/pavement painting is of two types: straddling (for centerline painting) and offset (for edge-line painting). The straddling type doesn’t affect the traffic much compared to offset. However, the riskiest situation is the edge-line painting on two-lane two-way traffic roads, because the traffic is moving in the opposite direction of the operation. The most difficult situation arises when the traffic has to be maintained in both lanes. In some situations, the traffic coming from one direction may need to let the traffic from the other direction pass by temporarily when the painting operation blocks a roadway (especially during edge-line painting). 6. Pavement markings: Pavement markings are very important as a guide to drivers and are also included as a moving operation as it involves marking the pavement by blocking the traffic in that zone for a short duration. This also blocks and slows down the traffic and creates similar problems as that of painting. However, in this case, care should be taken about the safety of the unprotected (not inside a vehicle) workers working on the roadways, as sometimes vehicles coming at high speeds may lose control. 7. Crack filling/patch work: Crack filling/patch work is a really “hectic” maintenance operation of the roadways and the roadway may be blocked for up to half a day in the case of a high-volume road. This type of work involves flagger operations, which act as a signal for the moving work zone. In addition, high-strength materials are used here so that the road track becomes usable after a short while. However, workers are responsible for guiding the public to stop and move off to the shoulder and also make them stop until the work is done. In other situations, O/M workers may simply wait for a break in traffic and walk out into the traveled path to fill a crack.
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8. Curb and surface repairs: Curb and surface repairs are usually done by smaller trucks and equipment (e.g., pick-up trucks and even golf-cart-type buggies), which do not have as much protection or visibility when positioned next to moving vehicles. Therefore, curb and surface repairs can become a risky operation in a busy roadway. This type of repair work also blocks the traffic road for a while and thus makes the normal traffic flow slower and may distract drivers. 9. Flagger operations: Flagger operations take place generally on a two-way two-lane highway where the roadway is partially blocked for a moving O/M activity. The portion that is blocked is guarded by two flaggers or signals on either side, which stops the flow of traffic on the lane where work is going on, letting the traffic move on the other lane and, then, the flow is reversed (opposite lane traffic is halted and the disrupted lane traffic is allowed to pass). This is a timed activity and attention is given to the fact that traffic is affected by the O/M activity. 10. Replacing/repairing the signals and signage: Many sign-replacement and repair tasks occur at the side of the road and most times do not disrupt the traffic flow. If the work is on the shoulder, it is safer than in the traveled lane, but workers who are very close to the track (within 15 ft) are at risk. Special precautions are needed so that workers do not mistakenly enter the traveled roadway/street. In some instances, barricades need to be put up to keep the traffic flow from the work-zone. In case of repairing or removal of the signage over the roadway, boom trucks are generally used, which also block the roadway and disrupt the traffic to a great extent. 11. Loading/unloading material for maintenance operations: This is an activity where the trucks may block traffic while unloading/loading material, for maintenance of signals and signage, for instance. If it is a low-volume road, the problem is not as significant compared to a high-volume road. However, the associated risk events are quite dangerous. On a two-lane two-way road, loading/unloading material can block the vision of the vehicle operators. Moreover, the vehicles trying to pass the obstructing truck may move onto the side lane and cross the centerline where vehicles are coming from the opposite direction. Pedestrians, on finding that the sidewalk is blocked, may also try to pass the truck by coming onto the roadway. 12. Shoulder grading: Shoulder grading involves the shaping and stabilizing of unpaved roadway shoulder areas. This maintenance activity can be completed year-round, but is usually programmed between April and November in Iowa. A shoulder-grading crew utilizes about 10 workers on the road, in addition to graders, dump trucks, a belt loader, a roller, and usually a street sweeper. Therefore, this activity has a significant impact on the traffic as it involves several types of equipment that block the roadway and slows down traffic. 13. Repair, maintenance, and installation of guardrails, cable rails, and barrier rails: Guardrails and cable rails may be very close to the traveling lanes, just at the edge of the shoulder, and these rails frequently need repair or replacement when they are hit by a vehicle. Many times, if their damage is projected outside the roadway, they may be replaced or
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repaired without blocking the traffic. But, if the shoulder width is not enough or the damage is projected toward the traveling lane, it becomes a mobile work-zone condition. In these cases, a portion of the road needs to be closed temporarily. In addition, drivers tend to move toward the centerline of the road while passing the short length of the temporary work zone, which can pose risks if it is a two-lane two-way roadway. On the other hand, the repair and maintenance of barrier rails (mainly at the center of the road) and some guardrails and cable rails that are at the center of the road (such as for many bridges) present different work-zone conditions. Here, the risk is more for the safety of the workers rather than the traveling public. If a vehicle loses control and crosses the centerline, bridge deck crews have limited time or routes to escape from that situation, particularly vehicles coming from the opposite direction. 14. Maintenance of sanitary and storm sewer and water main: In this case, the equipment is kept on the shoulder, but if the space is not adequate, some parts of the roadway need to be blocked, which, again becomes a moving work zone. 15. Ditch cleaning: Similar to sanitary and storm sewer and water main maintenance, ditch cleaning is not a high- risk event in most cases, except for potential driver distraction and that traffic may become a little slower if a part of the roadway is blocked. 16. Cleaning storm sewer intakes and structures: This activity is similar to sewer and water main maintenance and ditch cleaning. 17. Survey work: Survey work is a moving operation that often needs to block the roadway for a short while. One of the main problems is that survey work uses minimum work-zone signage, which creates several problems, particularly on two-way highways. In many cases, drivers do not understand what the survey crew is doing. Moreover, vehicles moving at high speeds need time to lower their speeds, for which proper signage should be installed at a certain distance from the work zone. 18. Ingress and egress from construction site: Ingress and egress from the construction site is a risk event created when trucks load and unload materials needed for repairs and maintenance jobs for signals and signage, among others. The trucks need to slow their speed when they ingress the work-zone site and need to separate themselves from the moving traffic. This often creates a problem on high-volume roads as the traffic behind the truck also needs to slow down. Again, the same problem arises at the time of the egress from the work-zone site. The trucks need to come back to the normal traffic flow by entering the right lane and gaining the required speed. This activity also blocks moving traffic to some extent and proper signals need to be given so that accidents and head-on collisions can be avoided. 19. Electric/power system maintenance and street lighting: In many states, the electric/power system is overhead, above the traveled lane, so repair or maintenance of such overhead lines requires the use of boom trucks, which may block the roadway and disrupt the normal traffic
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flow. These activities can also distract driver attention and force drivers to move toward the centerline of the road. Proper attention should also be given to the safety of the crews working in these kinds of work-zones as workers in overhead buckets have little mobility or protection. 20. Snow removal: Generally, snow plows are used to move snow from the roads and streets, but, they may be unobserved by drivers, which can lead to accidents. In addition, removing snow frequently requires end-loaders to back into traveled lanes, especially in urban areas (streets). Because of the unique characteristics of snow removal, it is excluded from this study. B. Environment 1. Nighttime operations: To avoid the high volume of traffic in rush hours, some operations are done at night. But, night operations on bridges are risky for both materials testing and maintenance operations. Coring, painting, some patching work, debris pick-up, and different barrier rail repairs are done at night rather than in the daylight. In all these cases, the major issue is lighting of the work zone. If the work zone is properly illuminated, problems are minimized. But, most of the mobile work zones require portable lights, as many of the working regions may not have proper street lighting. 2. Rutted roadways: Due to weathering effects, the roadway tracks in the traveled lanes can become deteriorated and the middle of the tracks may have potholes. This often affects driver behavior as, to avoid the potholes, drivers try to move toward the edge of the road and may hit signs or guardrails. Sometimes, drivers are forced to move toward the centerline and therefore shift lanes to where vehicles are moving at a different speed (divided four-lane) or vehicles are coming from the opposite direction (two-lane two-way). Unanticipated movements such as these can create risks in mobile work zones. 3. Small towns or schools nearby: If the work zone is near a small town or a school, the work in that area needs to be scheduled according to the timing of the local peak traffic flows. For instance, in the case of a school, the work needs to be stopped near the time when school starts or ends. Roadways cannot be blocked at those peak hours as that causes real inconvenience to the public and also increases the risk factor to a higher degree. 4. Ramps and roadway intersections: If work is at intersections or ramps, proper signals and signage are often not installed for the drivers coming from the other lanes where no work is being performed. Proper attention should be given to the movement of these vehicles (on the intersecting or merging roads/streets), so those motorists know of the work zone ahead. Without such configurations, entrance to the work zone cannot be controlled. Signage and warnings are needed on both sides of the ramps. Again, all signage should be pertaining to the current work situation and thus needs to be updated according to the progress of the work.
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5. Pavement markings: This type of work is done generally in the morning hours to avoid disruption of traffic, especially at intersections. 6. Roads in hilly areas: In hilly areas, sight distance is problematic. In any hilly work-zone area, flaggers may be employed ahead of stoplights to make sure information about the work zone is communicated to the public at the appropriate time and distance and to make sure convoys stay together. 7. Peak traffic hours: Work should be scheduled in moving work zones according to the traffic hours. Generally, in peak traffic hours on high-volume roads, the work is stopped for a while and is again resumed after the peak hours. 8. Variable travel pattern: In some areas, different institutions (like the Iowa DOT, University, and Animal Disease Lab in Ames, Iowa). create different and variable peak travel times. Therefore, some decisions on moving operations require local knowledge or input. 9. Work near railway crossings: Work near railway crossings should be done very carefully and also needs to be stopped when a train is approaching. Therefore, this work should be coordinated as much as possible with train schedules. 10. Responding to emergency vehicles: In these cases, the work is brought to a temporary halt and the emergency vehicle is allowed to pass by. 11. Unforeseen weather conditions: The weather conditions in Iowa can be quite variable and difficult to predict, especially in the last three years. Flexibility to move to another site for O/M work is needed if the weather is bad in the region where work was originally planned. For instance, if a large area is experiencing heavy rain or dense fog, the scheduled operation needs to be shifted to a different area. 12. Fog and mist: Fog or mist is a temporary weather situation that affects visibility for a short time (usually early mornings) and/or in a small area (river valleys). In this situation, either special signals are used to warn drivers of a mobile work zone nearby or, if the situation worsens, work is brought to a temporary halt. 13. Different rules in shared jurisdictions: Different rules can apply when work moves “across the street” in a shared jurisdiction, which mainly includes city streets, DOT routes, and institutional routes (such as within Iowa State University). This sometimes creates confusion among drivers, contractors, utility companies, etc. and may cause inconvenience (permits, notifications, coordination, etc.) to the working crews in the different mobile work zones. 14. Special events: Different special local events such as parades, races, and fairs are carried on in local cities and towns, which may block the road for a while. These also stop the work in the O/M work zone for a while to give space for the events to take place.
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C. Equipment 1. Falling-weight deflectometer: This type of equipment is used to test the strength properties of the pavement and subgrade. This equipment is mounted on a moving vehicle, which stops in the lane to test at different locations. Because it is stop-and-go, it hinders the normal traffic flow to some extent. 2. Straddling painters: These are mobile painting machines used to paint the centerline of roads. Usually, they do not block traffic but will slow traffic flow in both directions. 3. Maintainers on gravel roads: No signage is used during this operation. Most work is on low-volume roads with local traffic only that is knowledgeable of the operation. 4. Cold-mix patchwork: Generally, when cold mix is put in a hole on the roadway, traffic is not affected and no signage is used for this activity. 5. Friction testing: This machine can disrupt traffic because of the water that is applied to the roadway surface during the three-second test at 40 mph. 6. Media trucks: Although the work is for a short duration, these vehicles and their operators frequently lack safety protocols while working. They may block the road for more than two hours and often do not use any proper signage, which can disrupt the movement of traffic. 7. Trucks carrying rock/aggregate: Many times, rocks and other aggregate may fall on the roadway while being hauled, sometimes cracking the windshields of the following vehicles. Proper signage should be used and precaution should be taken. 8. Boom trucks: These trucks are mounted with long booms, which are used to maintain and repair signage and signboards across the road lanes and also help to repair the overhead electric lines at times. 9. Pick-up trucks: This is a light-weight motor vehicle used to carry light material, tools, and equipment from one place to another or during inspections. 10. Street sweepers: A street sweeper or street cleaner refers to a machine that cleans streets, usually in an urban area. 11. Jet vac: This equipment is used for cleaning the leaves out of storm or sanitary intakes and structures. 12. Paint carts (hauled on trailers): Paint carts are usually used when painting roads and pavements in urban areas (e.g., turn arrows and crosswalks).
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13. Proper signage: Proper signage at different types of moving work zones is a necessity in preventing accidents and warning drivers in advance about the work zone. The signage should be changed as the work progresses so that current information can be conveyed to the public. 14. Fluorescent diamond signs: These types of signs should be used at the back of the vehicles and equipment to notify the drivers coming from behind that a moving work zone is ahead. 15. Use of lights/blinkers: Several types of lights and blinkers are used in the mobile O/M work zone with little standardization. 16. Fluorescent borders: In some mobile work zones where work is conducted mainly at night or equipment is stored overnight, fluorescent-colored indicators form borders on signs to signal that a mobile work zone is ahead. 17. Speed limit fines: Fines for mobile operations generally do not exist as they do for other construction activities, so drivers may not be as aware or as careful in these types of operations. D. Relationships 1. Coordination with municipalities: Many times due to lack of communication, local events have an impact on O/M activities. This is probably a bigger problem for centralized state activities than for local (e.g., county) activities. 2. Advantage of closed roads: For many types of O/M activities, preference of work should be given to roads that are temporarily closed. However, due to lack of coordination and information, static and mobile operations often run into each other. 3. Coordination between state and local agencies: Sometimes due to lack of information, state and local agencies may come to work at the same place at the same time, which may create a problem. 4. Worker safety and training programs: Younger and temporary O/M workers are not given enough training, which may lead to inefficient work and an unsafe work zone. 5. Train the trainers: This philosophy is used to train all the employees of the organization to the extent required only for performing their particular work. Supervisors are given training, which they in return deliver to the employees in their team. If any additional problems occur, it is generally escalated to the supervisor. 6. Control of right-of-way (ROW): Frequently, ROW managers are not aware of O/M activities occurring in the ROW. While the DOT tries to coordinate ROW permits, they don’t always get a copy of the final permit. In some local and institutional situations,
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communication or coordination is lacking when control of the ROW changes. Private utilities and contractors making taps or upgrades in streets or ROWs should get a new ROW permit form, which contains a requirement for traffic-control planning, but this doesn’t always happen. 7. Third-party interaction: There is subcontracted maintenance and repair work on some major utility repairs, especially directional drilling for electrical conduit. There are also O/M activities on shared jurisdiction roads. Neighborhood groups often do not communicate upcoming activities. O/M also tries to coordinate with law enforcement on issues such as missing signs or placement of stop signs. O/M also needs to coordinate with railroads and utilities on maintenance of rail crossings and utilities under the railroad.
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APPENDIX C. EXPERT INTERVIEWS This appendix includes information from three in-depth follow-up interviews with experts. Follow-Up Interview with Bob Younie, State Maintenance Engineer Discussions with Bob Younie mostly included an overview of the chain of command in the Iowa DOT and what can be done internally to help mitigate risk. In more recent years, the Iowa DOT has decided to flatten their chain of command in an attempt to cut back on overhead expenses. The overhead costs have been diminished, but so have other portions of operations that maybe should not have been. For example, the total number of man hours spent in training in 2000 was roughly 103,000 hours, compared to 2010, when roughly 44,000 man hours were allocated to training, which includes safety training. Included in this interview summary are organizational charts for Iowa DOT staff and their positions in the Highway Division and the District 2 Highway Division for reference on how the organization is currently set up (Figures C.1 and C.2). One of the main points of concern that Bob brought up was the lack of emphasis on coordination of training and safety programs. Bob expressed that he was more concerned with managerial operations that addressed safety and risk mitigation than with dangerous working conditions. In short, the problems in executing safety procedures come from poor training strategies and that, if strategies were adjusted, the outside (worksite) risk factors would become less of a problem. Because of the flattening of operations, more work has been assigned to division and shop managers, which means less time in the work week for managers to hold training sessions. At one point in time, most garages were managed by a single supervisor. Today, the trend is that an individual manager now is responsible for two to four maintenance garages, cutting their ability to supervise all operations or O/M crews directly and effectively. Along with not being able to hold as many training sessions, shop managers, as well as division managers, are not available to hold “Job Box Talks” or to have daily safety reminders. Because of the increased span of control (two to four garages instead of one), managers also find it difficult to schedule face-to-face meetings with O/M field crews to discuss things that are unique to a certain job or area they are working on for that day. These daily reminders are often the best line of defense when it comes to safety for an individual operator, because they are hearing from their direct supervisors and can know that their safety is in their supervisor’s best interest. Shop managers likely have the most experience when it comes to jobsite safety, especially when it comes to a regional or local problem area.
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Figure C.1. December 2010 Iowa DOT Highway Division organizational chart
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Figure C.2. December 2010 Iowa DOT District 2 Highway Division organizational chart 85
Another point of emphasis that Bob brought up is that there may not be enough Best Practices meetings held within divisions. If a local garage or division finds that a certain process works better than another does, it does not seem to filter out to other garages as quickly as it should. It was suggested that shop managers be encouraged to meet with division managers and other shop managers to discuss best practices that are discovered in the field, especially when it comes to safety. It was also encouraged that division managers call meetings periodically to encourage this type of information sharing. In further discussion about safety training, Bob was not convinced that adequate training was being taught on all levels, especially at the supervisory level. He felt the DOT currently is not doing enough to prepare its garage supervisors to manage safety in their local regions and, in turn, their operators are not receiving a well-rounded safety training background. The amount of formal training does not seem to be translating into peer training or the ability for one operator or laborer to identify a safety problem and show another why they are working unsafely. Interview with Mark Black, Iowa DOT District 2 Engineer After review of the Maintenance Instructional Memorandum (IM) there were a few suggestions that Mark Black discussed maybe should be changed on a broad level that their garage has already implemented. On top of the IM review, Mark also suggested that the Traffic Control Manual be reviewed, as well as the Flagger’s Handbook. (The researcher’s later discovered this Traffic Control Manual is a reference that the district put together and updates each April and October to coincide with revisions to the Standard Road Plans, which are available athttp://www.iowadot.gov/erl/index.html.) The Traffic Control (TC) Manual at one point in time was included in the Maintenance IM as an appendix but grew over time to include a wide variety of differing work-zone set-ups. At some point, recently, the traffic control diagrams (labeled Traffic Control Standard Road Plans – TC Series online) were removed and compiled into a separate standalone binder. Following are the issues that Mark Black would like us to consider in our study. At the point in time when the TC Manual became a separate publication, the references from the Maintenance IM to the diagrams in the TC Manual never changed. When these diagrams were included as references in the in the Maintenance IM they were annotated as RC diagrams (RC-1, RC-3). The RC designations are no longer used, but are still referenced in some places. Now that traffic control diagrams are in a separate TC Manual, the titles of the diagrams have changed (e.g., TC-1). This makes referencing diagrams from the Maintenance IM difficult. Another problem with the references to the traffic control diagrams is that the Maintenance IM still refers to an appendix that once included these diagrams, indicating that a section of the Maintenance IM is missing, rather than recognizing that there is now a separate manual for Traffic Control. This causes problems for crew foremen, because they are confused as to which
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diagram to use. The result is that neither the TC Manual nor the Maintenance IM is used as efficiently and thoroughly as intended. The second problem that should be considered is the location of diagram-specific notes in the TC Manual and how they should be referenced. As it stands now, the diagram-specific notes are still located in the Maintenance IM , indicating they did not travel with the diagrams, as they should have when the TC Manual became a separate publication. The required cross-referencing between the Maintenance IM and the TC Manual was never completed. Mark indicated that the notes included in the diagrams were just as important as the diagrams themselves, because they have control standards that vary from job to job. For example, for a certain working activity, if the work zone is less than a quarter of a mile, certain safety measures are used and, if the work zone is longer than a quarter of a mile, a different set of standards are used. Without reading the notes that are associated with a traffic control diagram, a crew foreman may miss these operational standards completely. Mark indicated that not reading through these notes for specific traffic control setups could be extremely hazardous and hinder the ability to protect the workers of the operation properly. An example of a traffic control diagram is included as Figure C.3. This would be the only reference for a crew foreman. The diagram has no indication of the supplemental notes that should be evaluated in this work zone. Also note the title of TC-202 in the bottom right corner, which was not always the standard title. The traffic control diagrams (Standard Road Plans – TC Series) can be found athttp://www.iowadot.gov/design/stdplne_tc.htm.
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Figure C.3. Sample traffic control diagram for a shoulder closure
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The third topic discussed by Mark is the use of truck-mounted attenuators (Figure C.4).
Figure C.4. Truck-mounted traffic attenuator Mark indicated that these types of vehicles in a mobile operation are the first piece of equipment that actually is in the lane of traffic. He indicated there are inherent problems when using this equipment. The problem with this type of equipment is that it is designed to push traffic over to another lane, but it is not designed to handle the impact of being struck by a moving vehicle. The single biggest threat, Mark said, was that vehicles such as semi-trucks and trailers did not have the ability to stop and have caused catastrophic damages including loss of life and extreme property damage. The incidents Mark discussed also showed that references to the diagramspecific notes could have been reviewed more thoroughly as conditions such as traffic volume had changed over the course of several years of work. Interview with Jeff Koudelka, Vice President of Iowa Plains Signing, Inc. Iowa Plains Signing does many different types of work involving mobile operations including line striping and installing temporary barrier rails and is often accountable in other mobile operations for many other safety measures. About 95 to 97 percent of their work is subcontract work. The primary concern that Jeff expressed with relation to mobile operations is the ability to attract driver attention and drivers’ abilities to identify and respect the mobile work zone. He feels driver distraction causes many more incidents than any failure of their own to adhere to safety standards. To help curb this problem of drivers’ not paying attention to changing roadway conditions, strobe-type warning lights have been installed on every vehicle used in their mobile fleets. This is not a DOT safety standard; rather, it is a practice implemented by Iowa Plains Signing that goes above and beyond the typical standard. Another point of concern was the inability to keep vehicles from changing lanes between vehicles in the operation rather than passing all of the vehicles in the line at once (Figure C.5).
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Figure C.5. Desired versus dangerous passing path The dangerous passing path around and between the O/M vehicles poses two major issues in that the contractor is no longer able to control the entire work zone that the passenger vehicles are traveling through and presents two points where drivers potentially cut off maintenance vehicles too closely when passing rather than one. Passenger vehicles often do not allow enough space when returning to the traveling lane between themselves and the maintenance vehicle. This poses a major threat to persons who are on equipment that does not enclose the operator. A source of this danger often comes from too many maintenance vehicles in a fleet that is operating on a two lane-two way highway. In addition, the Iowa DOT Traffic Control standards do not seem to take into account that fewer vehicles are better for two-lane work, whereas more vehicles are better for multilane and interstate highway work. The third point of emphasis discussed in this conversation was the clarity of diagrams in the traffic control diagram and the inability to go above and beyond the standards shown. In several of the diagrams (such as TC-431) graphics of vehicles to be used in the fleet but near them is an indicator that the piece of equipment is optional. Jeff felt that if it is included in the road standard, the piece of equipment should not be optional and should always be included. Jeff stated that Iowa Plains Signing never allows a piece of equipment to be optional in an operation if it is shown as so on the DOT Traffic Control Standard. Also, oftentimes the vehicles that are depicted in the diagrams do not accurately show the realistic footprint of a piece of equipment. For example a rumble-strip grinder may be shown to be working outside of the traveling lane on the diagram but, in reality, the grinder may be sitting a few feet into the lane or even entirely in the lane of travel.
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The second part of this concern is that because Iowa DOT standards are very specific in how they should be implemented (number of signs, number of trucks), contractors feel they cannot go above and beyond the standards without being liable for damages outside of their work zone. Therefore, standards often constrict the contractor to perform to a standard that does not allow for additional safety measures. Because of all the past litigation Iowa Plains Signing has faced for not adhering strictly to the Traffic Control Standards over seemingly meaningless regulations, they are not willing to provide additional signage and other safety equipment. The last main topic of discussion was the lack of willingness to accept new safety products and implement them in Iowa DOT standards. One item that was specifically talked about is temporary rumble strips (Figure C.6).
Figure C.6. Temporary rumble strips Temporary rumble strips have the ability to grab the attention of drivers and alert them to the potential hazardous situations ahead and can be included in operations that require temporary set up in a specific area. Finally, some innovative items have been adopted in the Iowa DOT standards as recently as 2011. The latest equipment being used in traffic control are automated signal lights, which replace standard flagging controls. These signal lights allow for two fewer laborers to be outside of a vehicle and exposed to moving traffic.
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