Description
The New Zealand Transport Agency ('the Transport Agency') has a key interest in ensuring that transport infrastructure assets and services function continually and safely. This interest has led to a specific focus on the concept of resilience and how this can be defined, measured and improved across the transport system.
Measuring the resilience of transport
infrastructure
February 2014
JF Hughes and K Healy
AECOM New Zealand Ltd
NZ Transport Agency research report 546
Contracted research organisation – AECOM New Zealand Ltd
ISBN 978-0-478-41915-3 (electronic)
ISSN 1173-3764 (electronic)
NZ Transport Agency
Private Bag 6995, Wellington 6141, New Zealand
Telephone 64 4 894 5400; facsimile 64 4 894 6100
[email protected]
www.nzta.govt.nz
Hughes, JF and K Healy (2014) Measuring the resilience of transport infrastructure. NZ Transport Agency
research report 546. 82pp.
AECOM New Zealand Ltd was contracted by the NZ Transport Agency in 2012 to carry out this research.
This publication is copyright © NZ Transport Agency 2014. Material in it may be reproduced for personal
or in-house use without formal permission or charge, provided suitable acknowledgement is made to this
publication and the NZ Transport Agency as the source. Requests and enquiries about the reproduction of
material in this publication for any other purpose should be made to the Manager National Programmes,
Investment Team, NZ Transport Agency, at [email protected]
Keywords: criticality, failure, hazards, infrastructure, resilience, risk, transport, vulnerability
An important note for the reader
The NZ Transport Agency is a Crown entity established under the Land Transport Management Act 2003.
The objective of the Agency is to undertake its functions in a way that contributes to an efficient, effective
and safe land transport system in the public interest. Each year, the NZ Transport Agency funds innovative
and relevant research that contributes to this objective.
The views expressed in research reports are the outcomes of the independent research, and should not be
regarded as being the opinion or responsibility of the NZ Transport Agency. The material contained in the
reports should not be construed in any way as policy adopted by the NZ Transport Agency or indeed any
agency of the NZ Government. The reports may, however, be used by NZ Government agencies as a
reference in the development of policy.
While research reports are believed to be correct at the time of their preparation, the NZ Transport Agency
and agents involved in their preparation and publication do not accept any liability for use of the research.
People using the research, whether directly or indirectly, should apply and rely on their own skill and
judgement. They should not rely on the contents of the research reports in isolation from other sources of
advice and information. If necessary, they should seek appropriate legal or other expert advice.
Acknowledgements
The authors would like to acknowledge the following people for their assistance with this project:
Michael Nolan, Mark Gordon, Roger Fairclough, Dr Erica Seville, Craig Omundsen, Brian Sharman, Dr Cliff
Naude, Dr Ron McDowall, Gavin Armstrong, Brandon Mainwaring, Sandy Fong, Ian Duncan.
Abbreviations and acronyms
CDEM Ministry of Civil Defence & Emergency Management (New Zealand)
IPCC Intergovernmental Panel on Climate Change
NIAC National Infrastructure Advisory Council (US)
NIP National Infrastructure Plan
NIU National Infrastructure Unit
TMP traffic management plan
TOSE technical, organisational, societal, economic
Transport Agency New Zealand Transport Agency
UNDRO United Nations Disaster Risk Organisation
UNISDR United Nations International Strategy for Disaster Reduction
USDHS United States Department of Homeland Security
VTPI Victoria Transport Policy Institute
5
Contents
Executive summary ................................................................................................................................................................. 7
Abstract ....................................................................................................................................................................................... 10
1 Introduction ................................................................................................................................................................ 11
1.1 Background ................................................................................................................... 11
1.2 Purpose ......................................................................................................................... 11
1.3 Methodology ................................................................................................................. 11
1.4 Report structure and target audience ......................................................................... 12
2 Context of this study ............................................................................................................................................ 13
2.1 National Infrastructure Plan 2011 ............................................................................... 13
2.2 Responsibilities and perspectives on resilience ......................................................... 14
2.3 Challenges in planning for resilience .......................................................................... 15
2.4 Summary ....................................................................................................................... 16
2.4.1 Main points ..................................................................................................... 16
2.4.2 Relevance to framework development ........................................................... 17
3 The importance of resilient infrastructure ............................................................................................. 18
3.1 Why is resilience important? ........................................................................................ 18
3.2 Complex interdependencies ........................................................................................ 18
3.3 Summary ....................................................................................................................... 20
3.3.1 Main points ..................................................................................................... 20
3.3.2 Relevance to framework developments ......................................................... 20
4 What is resilience? .................................................................................................................................................. 21
4.1 Defining resilience ....................................................................................................... 21
4.1.1 Resilience, vulnerability and sustainability .................................................... 23
4.2 Hazards, risk and resilience ........................................................................................ 23
4.3 Dimensions and principles of resilience ..................................................................... 25
4.3.1 Dimensions of resilience ................................................................................ 26
4.3.2 Principles of resilience .................................................................................... 27
4.4 Summary ....................................................................................................................... 31
4.4.1 Main points ..................................................................................................... 31
4.4.2 Relevance to framework development ........................................................... 31
5 How can we measure resilience? .................................................................................................................. 32
5.1 Resilience to what? ....................................................................................................... 32
5.1.1 An all-hazards vs specific hazard approach .................................................. 33
5.2 Conceptual/qualitative frameworks ............................................................................ 33
5.3 Quantitative approaches .............................................................................................. 35
5.4 Recommended measurement approach ...................................................................... 35
5.5 Summary ....................................................................................................................... 36
5.5.1 Main points ..................................................................................................... 36
5.5.2 Relevance to framework development ........................................................... 37
6 A proposed measurement framework for transport system resilience ................................ 38
6.1 Resilience assessment context .................................................................................... 40
6.2 Resilience measures ..................................................................................................... 40
6
6.2.1 Application of weightings ............................................................................... 44
6.3 Summary ....................................................................................................................... 44
6.3.1 Main points ...................................................................................................... 44
7 Implementation of the framework ............................................................................................................... 45
7.1 Summary ....................................................................................................................... 47
8 Example assessments .......................................................................................................................................... 48
8.1 Regional all-hazard assessment ................................................................................... 48
8.2 Asset, hazard-specific assessment .............................................................................. 49
9 Conclusions and recommendations ............................................................................................................ 51
9.1 Conclusions................................................................................................................... 51
9.2 Recommendations ........................................................................................................ 51
10 References ................................................................................................................................................................... 53
Appendix A: NZ Transport Agency risk tool ........................................................................................................ 58
Appendix B: Resilience assessment example ...................................................................................................... 60
Appendix C: Resilience, vulnerability and sustainability ............................................................................. 74
Appendix D: Criticality ....................................................................................................................................................... 76
Appendix E: Hazards, rare events and failure modes .................................................................................... 78
Appendix F: User guidance ............................................................................................................................................. 82
Executive summary
The New Zealand Transport Agency (‘the Transport Agency’) has a key interest in ensuring that transport
infrastructure assets and services function continually and safely. This interest has led to a specific focus
on the concept of resilience and how this can be defined, measured and improved across the transport
system.
As a result, from late 2012 to mid-2013, the Transport Agency engaged AECOM to develop a framework to
measure the resilience of the New Zealand transport system.
The project involved initial research and scoping to determine the project boundaries and definitions, and
following this, the development of a practical framework and assessment tool.
The framework is applicable to the broad land transport system (road and rail) and allows consideration of
various scales (asset/network/region).
Critical infrastructure and hazards
Infrastructure is recognised as a critical element to healthy economies and stable communities. It enables
commerce, movement of people, goods and information, and facilitates society’s daily activities.
In a transport context, societies rely on transportation networks for their daily economic and social
wellbeing. The ability of the transport system to function during adverse conditions and quickly recover to
acceptable levels of service after an event is fundamental to the wellbeing of communities.
Furthermore, the risks to critical infrastructure from hazards are, according to research, increasing
globally. These hazards can include natural, technological, social and political hazards, each of which can
occur with a varying degree of predictability.
The hazard scenarios are further amplified due to complex interdependencies between modern
infrastructure networks, and the existence of many different failure modes – all of which can affect the
functioning of infrastructure.
What is resilience?
Resilience is considered the ultimate objective in the context of hazard mitigation. There is a variety of
definitions which have evolved as different disciplines have applied resilience thinking to their work and
adapted the definitions to meet their focus.
A definition which is both applicable to the New Zealand transport context and is consistent with
international literature is that provided within the Treasury’s National infrastructure plan (NIP):
The concept of resilience is wider than natural disasters and covers the capacity of public,
private and civic sectors to withstand disruption, absorb disturbance, act effectively in a
crisis, adapt to changing conditions, including climate change, and grow over time.
This definition acknowledges that the service the infrastructure delivers will be disrupted, due to damage
to the infrastructure; however, the service is able to reduce the possibility of failure, adapt and recover
from a disruptive event and/or gradual external changes over time. It also implies transformation, so not
only is the infrastructure service able to survive or recover but it can adapt to a changing environment in
which it operates. Finally, the definition is broad enough to encompass more recent approaches that allow
for ‘unknown’ as well as ‘known’ hazards.
Measuring the resilience of transport infrastructure
8
To further understand resilience, researchers have identified a number of dimensions, principles and
measures of resilience. By defining and categorising these dimensions and principles, the broad
framework elements can be built, from which meaningful and practical measures can then be developed.
The literature review identified two dimensions of resilience – technical and organisational – as being
representative of the range of broad considerations for assessing resilience.
Similarly, in terms of resilience principles, the following were chosen, grouped under the two dimensions
above. These principles form the basis for the framework development:
• technical principles: robustness, redundancy, safe-to-fail
• organisational principles: change readiness, leadership and culture, networks.
A framework for measuring transport system resilience
A broadly qualitative framework for measuring resilience was created, based on the dimensions and
principles described above. Specific, detailed measurement categories were developed under each of the
principles.
The framework involves an initial determination of the context of the resilience assessment, followed by a
detailed assessment of resilience measures, which combine to generate a resilience score ranging from 4
(very high resilience) to 1 (low resilience). These measures can then be aggregated and weighted as required.
4 Very high resilience – meets all requirements
3 High resilience – acceptable performance in relation to a measure(s), some improvements could be made
2 Moderate resilience – less than desirable performance and specific improvements should be prioritised
1 Low resilience – poor performance and improvements required.
A number of cross-cutting themes were developed to influence the context and approach of the resilience
assessment. These are summarised and discussed in the table below.
Table 1 Cross-cutting themes
Cross-cutting theme Discussion
All hazards/specific
hazard approach
The assessment can be undertaken in one of two ways:
1 An all-hazards assessment – based on an event due to any (unspecified)
hazard/failure, which could be either known or unknown.
2 A hazard-specific assessment could be undertaken. This would involve identifying the
relevant known hazard types and assessing the resilience to each.
Scale of assessment The framework will allow assessment at various scales: regional, network or asset.
Measures have been developed for each and the user can filter the questions accordingly.
Regional assessments could be aggregated to a national indicator if desired.
Shock event or stress
event
The framework will be able to evaluate both short-term shock events (eg earthquakes and
tsunamis) and longer-term stress events (eg climate change related).
In summary, the approach to undertaking the resilience assessment is as follows:
1 Determine the context of the assessment:
a all-hazards or specific hazards (including shock or stress event, rare events etc)
b scale: asset/network/regional
c shock or stress event
Executive summary
9
2 Undertake the assessment, using the relevant questions and assigning scores
3 Apply weightings to categories as required
4 Generate resilience scores for categories, principles and dimensions and a total score.
As a stand-alone assessment, the resilience measurement framework could be applied to generate a
relative score for comparing resilience across assets/networks or regions. However, to provide additional
rigour, other steps could be applied during implementation.
Implementation of the framework
To implement the measurement framework in a systematic manner, additional steps could be
incorporated to determine priorities for intervention. These steps include determining:
1 Which infrastructure should be assessed for resilience?
2 What level of resilience is appropriate for a given asset/network?
In order to answer these questions, an understanding is required of both the criticality of a given asset,
and the risk of a particular hazard occurring. Note, this corresponds directly to whether a general ‘all-
hazards’ or ‘hazard-specific’ assessment has been chosen.
The all-hazards approach would involve an assessment of criticality to determine which assets should be
focused on for the resilience assessment. The criticality assessment would identify which assets merit a
certain ‘desired’ level of resilience, and then following a resilience assessment for these assets, related
improvements or interventions could be targeted.
If further detail was required, a more detailed hazard-specific assessment could be undertaken. This would
provide information on the relevant hazards and the likelihood of their occurring. In this case, the output
of the risk assessment would determine the ‘desired’ level of resilience.
The Transport Agency currently has a risk assessment tool based on AS/NZS 31000, as well as a state
highway classification system that could be utilised to determine criticality of assets. The rail system and
local authorities may have similar methods for determining criticality.
In terms of application across different scales, the following approaches could be implemented. Any
approach could be used at any scale; however, the following are considered the most appropriate.
• Asset scale: Either an ‘all-hazards’ approach using criticality as a first step, or a hazard-specific
approach using risk assessment. Resilience assessment would be compared against ‘desired’ level of
resilience for the asset to determine the need for intervention.
• Network/route scale: Either an ‘all-hazards’ approach for all critical assets within the network using
criticality as a first step, or a hazard-specific approach using risk assessment. Resilience assessment
would be compared against ‘desired’ level of resilience for the network to determine the need for
intervention.
• Regional scale: Stand-alone resilience assessment either via an ‘all-hazards’ approach or a hazard-
specific approach. This would enable regions to be compared, and actions and interventions to be
prioritised across regions.
Conclusions and recommendations
The framework developed through this study is applicable to the broad land transport system (road and
rail) and allows an assessment at various scales (asset/network/region). It also gives effect to the guiding
principle of resilience within the NIP.
Measuring the resilience of transport infrastructure
10
Due to project constraints, detailed real-scenario testing of the framework was not undertaken. Specific
operator knowledge of assets and the relevant organisations would be required to undertake a meaningful
assessment. As such, this and other recommendations for future work are made below.
• Undertake a real-scenario testing of the framework with key operational staff.
• Undertake further work to improve understanding of critical infrastructure and factors which may
determine criticality – from both an economic and societal point of view.
• Undertake further economic and engineering research to better understand and quantify a suitable
level of investment in technical (structural) resilience. This is generally where significant capital
expenditure is required and is difficult to justify when funding is limited
• Improve understanding of linkages between resilience and sustainability. To date, conversations
around infrastructure resilience have occurred largely in isolation of those which occur around
sustainability.
Abstract
Internationally there is a growing call to improve the resilience of our critical infrastructure. This is in
response to a realisation that the services we take for granted may be robust in the face of predictable
hazards/failures, but are in fact extremely fragile in the face of unanticipated shocks.
In the context of transport infrastructure, operators strive to ensure that transport assets and services
function continually and safely in the face of a range of existing and emerging hazards. This has led to a
specific focus on the concept of resilience and how this can be defined, measured and improved across
the transport system.
The theory of resilience was researched and a measurement framework has been proposed that broadly
covers both technical and organisational dimensions of resilience and breaks these down into specific
principles and measures which can be utilised to qualitatively assess resilience.
The measurement of resilience was approached from a view that a risk management approach alone is not
sufficient and needs to be complemented by an awareness that resilience requires both consideration of
events that fall outside of the realms of predictability and, importantly, that failure is inevitable.
1 Introduction
11
1 Introduction
1.1 Background
The New Zealand Transport Agency (the ‘Transport Agency’) is primarily responsible for managing
New Zealand’s state highway network. It is actively involved in strategy and planning at a national and
regional level, with a strong focus on integration with both rail and port services.
Additionally, the Transport Agency has a key interest in ensuring that transport infrastructure assets and
services function continually and safely. This interest has led to a specific focus on the concept of
resilience and how it can be defined, measured and improved across the transport system. This was
highlighted by the National infrastructure plan 2011 (National Infrastructure Unit 2011), which identifies
‘resilience’ as one of six guiding principles to ‘provide a platform for infrastructure development’ and
‘signal how the country should move forward and make better decisions in the future’.
1.2 Purpose
The purpose of this research was to develop a framework and assessment tool to measure the resilience
of transport infrastructure, which is practical and feasible to implement, and which:
• will be applicable to the wider land transport system (road and rail), and will allow consideration of
various scales (asset/network/region)
• can link to broader criticality and risk management approaches allowing prioritisation of
improvements and interventions.
1.3 Methodology
A three-staged approach was followed, as illustrated in figure 1.1:
1 Initial research and scoping – including literature review and definition of the term ‘resilience’
2 Development of a framework and assessment tool, which is practical and feasible to implement
3 Implementation example.
The project team consisted of New Zealand based and international AECOM staff. The review was
undertaken both by key Transport Agency staff and steering group members consisting of staff from the
Treasury and Ministry of Transport. Finally, two peer reviewers were engaged to provide input following
each stage of the project.
Measuring the resilience of transport infrastructure
12
Figure 1.1 Outline of project methodology
1.4 Report structure and target audience
This research report has been developed in-line with the three-stage methodology and designed to guide
agency management and operators in their engagement with transport resilience in New Zealand.
Chapters 1 to 5 relate to work undertaken during stage one, and detail the objectives and background of
the study, define key terms, context and key considerations for measuring resilience. More specifically:
• Chapters 1 and 2 provide introduction and context.
• Chapter 3 discusses the importance of resilience and different stakeholder perspectives.
• Chapter 4 defines resilience, and related dimensions and principles
• Chapter 5 discusses how resilience can be measured and also what hazards are of relevance
• Chapters 6 and 7 bring together the preceding work and cover the development of the proposed
measurement framework and recommend specific measurements for resilience, as well as providing
suggestions around implementation and linking to existing criticality and risk frameworks
• Chapter 8 gives some examples of implementation.
• Chapter 9 contains the conclusion and recommendations for future work.
2 Context of this study
13
2 Context of this study
This section covers the context in which the resilience framework and resilience measures must operate.
The New Zealand government has released a number of publications which establish guidance principles,
context and direction for the provision and management of infrastructure in New Zealand.
The first of these is Working towards higher living standards for New Zealanders (Treasury 2011b). This
publication focuses on how improved economic performance can lead to enhanced living standards and
outlines a series of dimensions which contribute to achieving this. These dimensions include ‘reducing
risk’, and ‘improving New Zealand’s ability to withstand unexpected shocks’. In the context of physical or
social infrastructure, this could be viewed as building resilience.
Additionally, Treasury has published Better business cases (Treasury 2012) and the Better capital planning
and decision making (Treasury 2011a).
The purpose of these two complementary publications is to deliver better value for money through public
investment and ultimately better outcomes and service delivery to the public. The key messages focus on
robust planning, analysis, decision-making and implementation in order to ensure project success.
Treasury (2011a) covers the fundamental principles of good asset management and planning, which, in
turn, incorporate an assessment of critical assets and business risk when developing business cases.
Finally, Treasury has released the National infrastructure plan (NIP) (NIU 2011). This document establishes
resilience as a key area of focus and is discussed further below.
2.1 National Infrastructure Plan 2011
The NIP covers the transport, telecommunications, energy, water and social infrastructure sectors, and
sets out a vision that ‘by 2030, New Zealand’s infrastructure is resilient and coordinated and contributes
to economic growth and increased quality of life’.
The NIP establishes six guiding principles as a platform for infrastructure development: investment
analysis, resilience, funding mechanisms, accountability and performance, regulation and coordination.
For each of these principles a high-level assessment was undertaken for each sector (figure 2.1), with
resilience within the transport sector assessed as ‘occurs effectively’. It is understood that this high-level
assessment was not the result of a robust or evidence-based assessment (R Fairclough, pers comm).
In order to provide clarity and robustness to this high-level assessment, the NIP acknowledges that
significant work is required to develop indicators for the assessment areas shown in figure 2.1, both
within and across sectors. Agencies and industry bodies are therefore being encouraged to develop
indicators which are relevant, transparent, replicable and can be standardised.
In this context, the Transport Agency commissioned this research project to develop a framework to
measure resilience for the land transport system.
Measuring the resilience of transport infrastructure
14
Figure 2.1 NIP high-level assessment of current infrastructure situation
Source: Treasury (2011)
Subsequent to the publication of the NIP, the NIU has further developed its thinking around resilience and
how this applies to infrastructure. A series of eight resilience attributes have been developed which aim to
achieve a common understanding of resilience as it applies to national infrastructure. These are: service
delivery, adaptation, community preparedness, responsibility (voluntary and regulatory),
interdependencies (consideration of linkages), financial strength, continuous (vigilance and assurance) and
organisational performance (leadership and culture).
These attributes provide context to the measurement framework presented in this report and are
discussed further in section 4.3. Effort has been made in developing the framework to be clear on a) how
the framework elements ‘map’ to the NIU attributes, and b) how a specific assessment(s) could provide a
national-level picture of resilience performance.
2.2 Responsibilities and perspectives on resilience
In New Zealand, those utilities responsible for delivering and maintaining critical infrastructure have been
denoted ‘lifeline utilities’. These have been defined as part of the Civil Defence and Emergency Management
Act 2002. This act sets out which sectors are considered critical lifeline infrastructure (utilities) and includes:
transport, water, wastewater, stormwater, energy and telecommunications services. All lifeline organisations
have a direct interest in understanding and developing resilience to hazards across all the utility organisations
both because of their operational interdependence, and in their desire to function to their fullest possible level
of service. The framework set out in this report will allow consideration of these interdependencies and the
framework principles will be broadly applicable across the range of sectors/utilities.
In addition to the lifeline utilities, there are a range of other stakeholders – each of whom may have a
slightly different perspective on ‘resilience’. These perspectives influence priorities and where investment
is targeted to improve resilience. Table 2.1 below summarises these perspectives.
Table 2.1 Stakeholders and perspectives on resilience
Stakeholder Perspective
User:
The direct or indirect customer/user of the
infrastructure, which may be for business or
personal purposes. For example:
• direct – freight companies, or commuters
using the road network
• indirect – those who receive goods and key
supplies, such as supermarkets.
Users expect the level of service they are accustomed to, to be
restored following an event. They may accept a lower level of
service for a period of time that is proportional to the severity of
an event; however, they may be less accepting of a lower level of
service for extended periods.
The owner and operator of the infrastructure need to understand
the length of time the user will tolerate decreased levels of
service.
2 Context of this study
15
Stakeholder Perspective
Operator and maintainer:
Government agency, local government, utility
company or private contracted organisation.
Operators need to deliver resilience which does not adversely
raise the cost of maintenance and operational expenditure.
They have a key interest in interdependencies and potential
cascade failure.
Government/owner:
Both central and local government, related
agencies and utilities.
Government and related agencies deliver resilience for the
community, and therefore need to consider broader social as
well as economic objectives, with a key interest in
interdependencies.
Infrastructure reliability has political significance through the
way infrastructure disruptions are perceived by constituents.
Robust business cases are required for investment in resilience.
Funding organisation:
Private financier of capital and/or operations and
maintenance.
Funding organisations need to deliver resilience to protect the
investment in existing assets, with a focus on value for money
and a robust business case.
Insurer: The insurer has a vested interest in reducing the risk profile as a
result of resilience improvements.
From a national transport perspective, the Transport Agency is considered to be the owner’s
representative, operator and funder, ultimately interested in the best resilience outcome for New Zealand
as a whole. This report and the development of a measurement framework for resilience can be used by
the transport sector and will be applicable across a range of scales from regional and national down to the
asset level. Nonetheless, it is important that the perspectives of all stakeholders (especially users) are
considered when determining criticality of elements of the transport network and the corresponding
required levels of resilience (refer chapter 7).
2.3 Challenges in planning for resilience
Resource constraints and the requirement for robust business cases (refer above) put pressure on
organisations to justify all expenditure, and when this expense involves mitigating the risk of future and
uncertain hazard events, consensus among decision makers and stakeholders can be difficult to achieve.
As such, a method to assess resilience of infrastructure and prioritise improvements is considered
important and timely.
Ladbrook (2012) emphasises that building structural resilience requires deliberate choices early in the
development of a project. Opportunities for resilience can be lost if not planned and designed for prior to
implementation, as illustrated in figure 2.2. Decision making to build resilience requires a broad approach
that considers long-term infrastructure resilience and economic optimisation, rather than the sole, narrow
perspective of short-term ‘return on investment’ views.
Measuring the resilience of transport infrastructure
16
Figure 2.2 Opportunity to build resilience in planning and design
Despite this agreed need to build resilience, there are, however, few (if any) practical methods for the
application of resilience in engineering design. Park et al (2013) highlight a number of challenges that will
need to be overcome in order to design for resilience:
• Engineering challenges need to be seen as conditions to be managed, rather than problems to be
solved.
• Current approaches focus on known, identified hazards and ignore the significance of unidentified
hazards either via assumption or because of cost constraints. This issue is fundamental when
exploring resilience and risk, and one which is discussed further in subsequent sections.
• Current design practices are based on existing codes and are sanctioned by agencies. These codes
ignore the possibility of unidentified or emergent hazards, and lead to incremental evolution of
design, rather than encouraging innovative design.
While it will not establish parameters for engineering design, the framework set out in this report will
address some of these challenges and provide a method for assessing and measuring the resilience of
transport infrastructure, and identifying priority areas for improvement.
2.4 Summary
2.4.1 Main points
The NIP along with Treasury (2012) and Treasury (2011a; 2011b) all establish a context for understanding,
assessing and building resilience in infrastructure. In particular, the NIP provides key attributes for
resilient infrastructure.
There is a wide range of perspectives from which resilience can be assessed – ranging from user, through
to owner, operator, funder and insurer. Each has different perspectives and views on priorities.
There are challenges in planning and designing for resilience and justifying expenditure for mitigating
future, uncertain hazards. A long-term view is required and methods are needed that allow measurement
of resilience.
2 Context of this study
17
2.4.2 Relevance to framework development
The framework needs to:
• give effect to the high-level objectives of the above plans and documents
• relate to the NIP attributes developed
• be applicable across a range of scales (regional – asset), while assuming a national perspective (ie the
best outcome for New Zealand)
• address the challenge of unidentified hazards.
Measuring the resilience of transport infrastructure
18
3 The importance of resilient infrastructure
In this section we cover reasons why resilient infrastructure is important to society. We discuss this in the
context of increasing reliance on critical ‘lifelines’ infrastructure, increasing frequency of hazards and
evolving, complex interdependencies within infrastructure systems. We also explore how different
stakeholders can view resilience from different perspectives.
3.1 Why is resilience important?
Worldwide, infrastructure is recognised as a critical element for healthy economies and stable
communities. It enables commerce, movement of people, goods and information, and facilitates society’s
daily activities. Infrastructure can be considered to include everything from the physical infrastructure of
roads, bridges, airports, rail, water supply, telecommunications and energy services, to the social
infrastructure of health care, education, banking and finance services, emergency services and the justice
system.
Croope (2010) states ‘Critical infrastructure not only responds to the needs of society for the smooth daily
continuation of activities, but also provides the basis on which society exists and relies’.
Godshalk (2002) lists two reasons behind the importance of resilience.
1 Because the vulnerability of technological, natural and social systems cannot be predicted, the ability
to accommodate change without catastrophic failure in times of disaster is critical.
2 People and property fare better in resilient cities when struck by disasters. Fewer buildings collapse,
fewer power outages occur, fewer businesses are put at risk, and fewer deaths and injuries occur.
Societies have an increasing reliance on transportation networks for their daily activities. The ability of the
transport system to function during adverse conditions and quickly recover to acceptable levels of service
after an event is fundamental to the wellbeing of people within society.
The current increased focus on resilience is driven by a raised awareness of hazards due to recent natural
disasters, such as the Christchurch earthquakes, and other natural and technological hazard events globally
(eg the Fukushima nuclear disaster, Hurricane Katrina and the Deep Water Horizon oil spill). Climate change
is also affecting the severity and frequency of events, and creating new hazards in its own right.
Additionally, awareness of unpredictable, ‘rare’ events is increasing, and there is a recognition that
societies need to build resilience to these, in ways that may not have been used in the past.
Finally, complex interdependency in modern infrastructure networks means we need to look further afield
than the principal sector (eg roading network) to other interdependent sectors (eg electricity,
telecommunications) to identify potential failure modes and hazards. This is discussed further below.
3.2 Complex interdependencies
Modern infrastructure networks are increasingly complex and interconnected. These interdependencies
and their many dynamic and multi-dimensional parts necessitate a ‘system of systems approach’ (Croope
2010 and USDHS 2009a) in order to fully understand and assess where vulnerabilities lie and where
resilience can be improved. This is illustrated in figure 3.1.
3 The importance of resilient infrastructure
19
Figure 3.1 Connections and interdependencies across the economy
Source: T O’Rourke
These complex, interconnected systems create benefits and efficiencies at times of normal operation, yet
bring with them vulnerabilities and operational challenges, especially during unexpected circumstances or
when faced with hazards. Extensive analysis of complex engineering systems has revealed that in many
cases ‘failure’ is at best a statistical inevitability, or at worst a part of ‘normal’ operation (Perrow 1984).
Interdependencies can lead to a wide range of potential failure modes and the emergence of previously
unidentified hazards which can cause failure. Hollnagel (2011) categorises the range of failure modes as
simple-linear (or cascade) failure, complex-linear failure (caused through hidden interdependencies or
latent conditions), or complex-nonlinear failure resulting from concurrence of unexpected events. These
are discussed further in section 4.2.
Interdependence can be considered in a number of ways, including physical proximity, operational
interaction and interdependency of stakeholders (owner, funder, operator, insurer). Operational
interdependence can be assessed in terms of both upstream and downstream dependencies. As an
example, upstream for the Transport Agency are those systems/utilities whose failure would impact on
the functioning of its transport network (eg failure of electricity for signals), and downstream being the
systems/utilities which would be affected by failure of the Transport Agency transport network (eg a road
providing access to a power station fails, causing shut down). In the context of measuring resilience for
the transport system, the upstream dependencies are those that should be considered in terms of hazard
identification (with the downstream being important in assessing criticality).
It is considered vital that a detailed consideration and understanding of interdependencies and potential
failure modes is included in any assessment of resilience.
Measuring the resilience of transport infrastructure
20
3.3 Summary
3.3.1 Main points
Resilient infrastructure and specifically resilient transport infrastructure is vital to our modern society and
economy. The increased frequency, intensity and awareness of global hazard events mean that building
resilience is a justified and important goal.
Awareness of unpredictable, ‘rare’ events is increasing and there is a recognition that societies need to
build resilience to these.
Complex interdependencies in modern infrastructure systems necessitate a wide-ranging approach to
assessing hazards and potential failure modes.
3.3.2 Relevance to framework developments
The framework needs to consider the complete range of hazards, including rare events, and complex
failure modes as a result of inter-related, upstream dependencies.
4 What is resilience?
21
4 What is resilience?
This section provides a working definition for ‘resilience’ as well as recommending a series of appropriate
dimensions and principles which will feed into the measurement framework.
4.1 Defining resilience
Resilience is considered the ultimate objective of hazard mitigation, that is, ‘action taken to reduce or
eliminate long-term risk to people and property from hazards and their effects’ (Godschalk 2002).
The term resilience has evolved as different disciplines have applied resilient approaches to their work and
adapted the definitions to meet their focus.
Levina and Tirpak (2006) propose two key differentiators in resilience definitions, the first being the ability
of a system to withstand a disturbance without changing (whether by improvement or deterioration),
implying that no damage is done, and the second differentiator is the ability of the system to recover
when damage has occurred.
Maguire and Cartwright (2008) identify three views of resilience: resilience as stability, resilience as
recovery and resilience as transformation.
Manyena et al (2011) highlight that disasters are accompanied by change, and that instead of resilience
involving ‘bouncing back’ after an event, it should involve ‘bouncing forward’ and ‘moving on’. They argue
that ‘bouncing back’ does not signal change, and may involve returning to the conditions that may have
caused the disaster in the first place. They conclude that resilience can be viewed as the ‘intrinsic capacity
of a system, community or society predisposed to a shock or stress to bounce forward and adapt in order
to survive by changing its non-essential attributes and rebuilding itself’.
Bruneau et al (2003) illustrate the notion of resilience as it relates to the measure of seismic resilience.
Figure 4.1 demonstrates conceptually the measure of resilience over time from a single event (at t
0
) and
the restoration of ‘100%’ level of service (at t
1
). The diagram is a simplistic depiction as it does not show
the impacts from gradual changes over time (stress events), nor does it demonstrate adaptation (ie return
to an improved or altered state).
Figure 4.1 Conceptual measure 1 of resilience
Source: Bruneau et al (2003)
Other authors also quantify resilience as a function of the effort and resources required to recover from
the disaster as depicted in figure 4.2. This shows a rapid increase of effort after an event at t
0
followed by
a constant effort until the infrastructure is restored (t
1
) and then a gradual decrease.
Measuring the resilience of transport infrastructure
22
Figure 4.2 Conceptual measure 2 of resilience (recovery effort)
Recent work by Park et al (2013) describes resilience as an emergent property of what an engineering
system does, rather than a static property the system has. This viewpoint leads to different approaches to
dimensioning and building resilience, and focuses on continuous management, adaptation and new
approaches to design. This view is shared by Snowdon (2011) who contends ‘a resilient system accepts
that failure is inevitable and focuses instead on early discovery and fast recovery from failure’. A
fundamental factor in their respective approaches to resilience is the consideration of risk in the context
of ‘unknown’ hazard events, and the differentiation between a ‘resilience’ approach and a ‘risk’ approach.
This is discussed further in section 4.2.
With the above conceptualisations and views in mind, we have summarised a range of definitions:
• ‘Resilience is the capability of a system to maintain its functions and structure in the face of internal
and external change and to degrade gracefully when it must’ (Allenby and Fink 2005).
• ‘Resilience is the ability of systems, infrastructures, government, business and citizenry to resist,
absorb, and recover from or adapt to an adverse occurrence that may cause harm, destruction, or loss
of national significance’ (USDHS 2009a).
• ‘Resilience is the ability to survive a crisis and to thrive in a world of uncertainty’ (Seville 2009).
• ‘[Resilience is the ability of] a locale to withstand an extreme natural event without suffering
devastating losses, damage, diminished productivity, or quality of life and without a large amount of
assistance from the outside community’ (Mileti 1999).
• ‘The ability of a social or ecological system to absorb disturbances while retaining the same basic
structure and ways of functioning, the capacity for self-organisation, and the capacity to adapt to
stress and change’ (Solomon et al 2007).
Finally, it is necessary to highlight the NIP definition, which is as follows:
The concept of resilience is wider than natural disasters and covers the capacity of public,
private and civic sectors to withstand disruption, absorb disturbance, act effectively in a
crisis, adapt to changing conditions, including climate change, and grow over time (NIU
2011).
This definition acknowledges that the service the infrastructure delivers will be disrupted, due to the
infrastructure undergoing damage; however, the service is able to reduce the possibility of failure, adapt
and recover from a disruptive event and/or gradual external changes over time. It is considered the
definition is broad enough to encompass an approach consistent with the more recent views of Park
(2013) and Snowdon (2011) who recommend an approach that allows for ‘unknown’ as well as ‘known’
4 What is resilience?
23
hazards, as discussed above. It also could cover the ‘bounce forward’ idea proposed by Manyena et al
(2011).
As such, and for the purposes of this study, the NIP definition is considered appropriate.
4.1.1 Resilience, vulnerability and sustainability
There is a vast array of literature available on defining resilience and the relationship of resilience to other
commonly used (and often misunderstood) terms such as vulnerability and sustainability.
There are a variety of views on how they interact.
Vulnerability is a key concept for both disaster risk and climate change adaptation. It can be described as
a deficit concept (Malone 2009) and as such, resilience and vulnerability could be considered as two ends
of a spectrum (Levina and Tirpak 2006) with resilience being a positive measure. Folke et al (2002) termed
vulnerability the ‘flip-side’ of resilience.
On the other hand, vulnerability can be viewed as a component of resilience (Maguire and Cartwright
2008), or indeed as suggested by Brabhaharan (2006), resilience is a function of vulnerability (and other
factors). Therefore, the infrastructure can be assessed as vulnerable but still have a level of resilience due
to other influencing organisational, financial and social dimensions.
The following definition of vulnerability, adapted from UNDRO (1980) and UNISDR (2004), was adopted for
this study.
Vulnerability refers to the propensity of exposed elements such as human beings, their
livelihoods, and assets to suffer adverse effects when impacted by hazard events.
As for sustainability and resilience, Grubinger (2012) argues that the concepts overlap over a time scale,
with resilience being achieved in the short term via adaptation, and leading into sustainability over the
medium term through mitigation and ultimately reaching sustainability through transformation. This
could be illustrated through considering the example of sea-level rise due to climate change. Resilience to
sea-level rise-related hazards could be achieved in theory through a variety of structural, planning and
response activities/adaptations (such as relocation of houses and building of defences). Mitigation could
be achieved by lowering carbon dioxide emissions through reducing or substituting fossil fuel use. Finally,
sustainability would be the outcome of a long-term transition to a low (zero) carbon society.
Zolli (2012) proposes a relationship along similar lines and suggests that where sustainability aims to put
the world back into balance, resilience looks for ways to manage an imbalanced world. He goes on to
suggest that resilience is a more pragmatic and politically inclusive response to pressures – ‘rolling with
the waves instead of trying to stop the ocean’.
Sustainability has not been considered in this study, due to the specific focus on transport systems and a
desire to simplify the approach where possible. Recommendations are made, however, for future work in
this area in order to generate more clarity on the subject and identify opportunities to deliver benefits in
both a sustainability and resilience context (refer chapter 9).
For further discussion on the above relationships, refer to appendix C.
4.2 Hazards, risk and resilience
In order to further understand resilience, it is useful to consider its significance to both hazards and risk.
Measuring the resilience of transport infrastructure
24
Recent natural and technological catastrophes have highlighted a) a failure to predict extreme events, and
b) an inability to understand the complex systems involved and the potential range of failure possibilities.
Park et al (2013) emphasise our ignorance: ‘not the assumption that future events are expected, but that
they will always be unexpected’.
In general, hazards can be categorised into three general types: natural, technological and social/political
in nature. These can be further broken down into ‘stress’ events, that are long-term and gradual change
processes, and ‘shock’ events, that are short-term and sudden change processes. Appendix E contains
examples of the various types of hazards in these categories.
Hazards can also be classified as ‘known’ (or predictable) and ‘unknown’. Unknown’ hazards are also
called ‘rare events’, or in some instances, ‘black swans’. Taleb (2008) developed three characteristics to
describe black swan events:
1 They lie outside the realm of regular expectations, because nothing in the past can convincingly point
to their possibility.
2 They carry an extreme impact.
3 In spite of their outlier status, human nature causes people to concoct explanations for the occurrence
after the fact, making it explainable and predictable.
Furthermore, due to the range of complex interdependencies involved, there is a wide variety of possible
failure modes. In general, we have a poor understanding of how failures can propagate and amplify within
and across complex systems. Risks can emerge through non-linear interactions among system
components and generally only become observable after they occur. Hollnagel (2011) classifies failure
modes into three general types as summarised below (and discussed further in appendix E):
• simple, linear failure: failure of one asset triggering the failure of an interconnected and successive
asset (cascade)
• complex, linear failure: failure results from a combination of failures and latent conditions – often
hidden dependencies
• complex, non-linear failure: failure results from expected or unexpected combinations (concurrence)
of events.
Historically, a risk analysis approach has been used to identify risks and then develop
management/mitigation approaches. However, as many hazards and failure modes are unknown, risk
analysis becomes inadequate, and arguably impossible (Park et al 2013). In short, risk analysis requires
the hazards to be identifiable, and therefore, to prepare for the unexpected. An alternative (and
complementary) approach is required to consider these unpredictable events.
Some key differences in a traditional ‘risk-based’ approach versus a ‘resilience’ approach are as follows:
1 A risk-based approach looks to mitigate failure through probability and scenario-based analysis of
known hazards. A resilience approach looks to minimise the consequences of failure through
investigating scenarios with unidentified causes.
2 A risk-based approach would involve incrementally modifying existing designs in response to
emerging hazards, whereas a resilience approach would involve adapting to changing conditions, and
potentially allowing controlled failure (‘safe-to-fail’ design) at a sub-system level to reduce the
possibility of broader loss of function within the larger system (Park et al (2013) and Snowden (2011).
4 What is resilience?
25
These ‘risk’ and ‘resilience’ approaches are considered complementary and applicable in different
circumstances. They are not considered mutually exclusive, and their use will depend on the context of the
analysis being undertaken and the understanding of the relevant hazard. This is discussed in section 5.1.
4.3 Dimensions and principles of resilience
To further understand resilience, researchers have developed a range of dimensions, principles and
measures of resilience. Their relationship to the NIP attributes is indicated below. By defining and
categorising these dimensions and principles, the broad framework elements can be built, from which
meaningful and practical measures can then be developed. This section discusses dimensions and
principles, with chapter 5 addressing measures.
Figure 4.3 Relationship between NIP attributes and dimensions, principles and measures of resilience
The NIP 2011 defines a series of eight ‘attributes’ which help guide the definition and application of
resilience in practice. These are summarised in table 4.1.
Table 4.1 National Infrastructure Plan resilience attributes
NIP 2011 attribute Description
1 Service delivery
There is a focus on national, business and community needs in the immediate and
longer term. Resilient infrastructure delivers a level of service sufficient to meet
public and private needs, ensuring community viability.
2 Adaptation
National infrastructure has the capacity to withstand disruption, absorb
disturbance, act effectively in a crisis, and recognises changing conditions over
time.
3 Community preparedness
Infrastructure providers and users understand the infrastructure outage risks
(hazards) they face and take steps to mitigate these. Aspects of timing, duration,
regularity, intensity and impact tolerance differ over time and between
communities, and must be taken into account.
4 Responsibility Individual and collaborative responsibilities are clear between owners, operators,
users, policy-makers and regulators. Responsibility gaps are addressed.
5 Interdependencies A systems approach applies to identification and management of risk (including
consideration of interdependencies, supply chain and weakest link vulnerabilities).
6 Financial strength There is financial capacity to deal with investment, significant disruption and
changing circumstances. This includes available funds, the awareness of financiers
and insurers, continuing capital investment and maintenance expenditure.
Measuring the resilience of transport infrastructure
26
NIP 2011 attribute Description
7 Continuous On-going resilience activities provide assurance and draw attention to emerging
issues, recognising that infrastructure resilience will always be a work in progress.
Includes effective, on-going monitoring and auditing processes feeding back into
continuous improvement.
8 Organisational performance Leadership and culture are conducive to resilience, including resilience ethos,
situational awareness, management of keystone vulnerabilities and adaptive
capacity. Future skills requirements need to be addressed.
Source: NIU (2012)
These attributes are considered the over-arching considerations that then guide the development of a
resilience framework. The dimensions, principles and measures developed in this study will necessarily be
more specific and quantifiable. These are discussed further in the following sections.
4.3.1 Dimensions of resilience
It is important to understand different dimensions in order to develop an appropriate approach to
measuring and improving resilience.
USDHS (2009a) divides resilience dimensions into ‘hard’ and ‘soft’ systems, hard systems pertaining to the
technical and mechanical capabilities of infrastructure and organisations, and soft relating to the human
needs, behaviours and psychology within organisations and communities.
VTPI (2010) adopts a slightly different approach and breaks down dimensions of transport resilience into
five levels: individual, community, design, economic and strategic planning.
Bruneau et al (2003) developed four dimensions of resilience: technical, organisational, social and
economic (TOSE). They note that these four TOSE dimensions cannot be measured by any single
performance measure, instead they require different measures for each system under analysis.
A final, more simplistic, example is that developed by the US National Infrastructure Advisory Council
(NIAC 2010), which distinguishes between those practices related to people and processes and those
related to the structure of infrastructure and assets.
Both the NIAC dimensions and the TOSE dimensions serve as useful and relevant constructs for
understanding the high-level dimensions of resilience. They effectively encompass and summarise the
dimensions developed by VTPI (2010) and USDHS (2009a).
It is proposed that of the four TOSE dimensions, only the technical and organisational elements be
utilised, as illustrated in table 4.2. Because of the narrow focus on the transport system, the social and
economic dimensions are considered implicit as the network itself provides a vital social and economic
service, and its technical or organisational resilience will inherently provide flow-on social and economic
resilience. Economic considerations relating to the operator, and funding to deliver resilience, will be
covered within the organisational dimension.
Significant work has been undertaken in Australia (Governmental Resilience Expert Advisory Group) and
New Zealand (Resilient Organisations) to understand and develop more resilient organisations, especially
within the critical infrastructure and lifelines sectors.
It is vital that organisational resilience is given equal consideration to the resilience of the physical
infrastructure (technical resilience). Not only does this provide for improved outcomes for the overall
sector, but can also deliver enhanced leadership, enhanced reputation, lower costs, increased innovation
and many other tangible benefits (Commonwealth of Australia 2011).
4 What is resilience?
27
Table 4.2 Dimensions of resilience
Resilience dimension Description
Technical The ability of the physical system(s) to perform to an acceptable/desired level when
subject to a hazard event (Bruneau et al 2003).
Organisational The capacity of an organisation to make decisions and take actions to plan, manage
and respond to a hazard event in order to achieve the desired resilient outcomes
(adapted from Bruneau et al 2003).
Seville et al (2006) write that a resilient organisation is one that is ‘still able to
achieve its core objectives in the face of adversity’. They identify three aspects to
building resilience in organisations: a) reducing the size and frequency of crises
(vulnerability), b) improving the ability and speed of the organisation to manage
crises effectively (adaptive capacity), and c) an acute awareness of risk and an ability
to manage strategic risks as a process and not an event.
Source: Bruneau et al (2003)
The next section discusses specific principles of resilience that may apply to the dimensions above.
4.3.2 Principles of resilience
In previous sections we have outlined the complexity involved in understanding and defining resilience, as
well as the complexity in types of hazards and failure modes that can affect infrastructure. A number of
authors have developed comprehensive lists of principles for achieving resilience to enable common
understanding and direct efforts to improving resilience. This section discusses general principles of
resilience and then provides further detail specifically around organisational resilience principles.
4.3.2.1 General resilience principles
Foster (1997) identifies that in general, resilient systems are independent, diverse, renewable and
functionally redundant, with reserve capacity achieved through duplication, interchangeability and
interconnections.
VTPI (2001), Comfort (1999) and Foster (1997) have developed principles which include: redundant,
diverse, efficient, autonomous, strong, adaptable and collaborative.
Bruneau et al (2003) determine four principles: robustness, redundancy, resourcefulness and rapidity. To
these, NIAC (2010) adds the principle of ‘adaptability’ into incident response planning. Figure 4.4 clarifies
how these can apply prior, during and after an event.
Measuring the resilience of transport infrastructure
28
Figure 4.4 Resilience principles in sequence
Source: NIAC 2010
CDEM (2005) has established 4 R’s which are reduction, readiness, response and recovery. While these
overlap, they are more applicable to the field of emergency management and the cycle before, during and
after an event than to a specific resilience assessment.
Madni et al (2009) emphasise that resilience in engineering systems is more properly thought of as a
characteristic of how the system behaves (process), as opposed to a property that the system has (state).
Park et al (2013) acknowledge this and have established three overarching principles as follows, spanning
both the technical and organisational dimensions:
• Continuous management: Due to the unpredictability of complex systems, a resilience assessment
demands a constant, recursive process, often across multiple organisations. This process involves four
components: sensing, anticipation, adaptation and learning.
• Recognition of incompleteness: Complex systems are characterised by inherent uncertainty and
incompleteness across a variety of areas: internal and external factors affecting design and operation,
uncertainty in variability of shocks, and types and visibility of interdependencies.
• New approaches to design: Resilience requires a new approach to design thinking. Standard design
approaches tend to be based on incremental adaptations of previous approaches in response to a
failure. These approaches are generally inflexible and are difficult to change if unexpected conditions
are found. Resilient design requires new thinking and a departure from existing practices. Where a
traditional ‘risk-based’ design would result in a design that is resistant to hazards, a resilient design
would embrace uncertainty and failure via anticipation and adaptation (Anderies et al 2007).
Additionally, whereas a risk-based approach would typically generate a ‘fail-proof’ design (able to
withstand a range of known hazards), a resilience-based approach would account for unpredictability
through a ‘safe-to-fail’ design (Snowden 2006; Park et al 2013). This would entail planned, predictable
modes of failure that have been anticipated and designed for, as opposed to failure modes in a fail-
proof design which can often be brittle and catastrophic.
As can be seen many common themes run through the types of principles associated with resilience.
However, paradoxically many of these are combinations of apparent opposites: redundancy and efficiency,
diversity and interdependence, robustness and safe-to-fail, autonomy and collaboration, planning and
adaptability – adding weight to the importance of careful definitions and delineation between assessment
areas when building a framework.
4 What is resilience?
29
4.3.2.2 Organisational resilience principles
In regard specifically to organisational resilience, Commonwealth of Australia (2011) and Resilient
Organisations (various papers) have identified three core behavioural principles (with a range of indicator
subsets) which help define resilient organisations, as summarised in table 4.3 below.
Table 4.3 Organisational resilience – behavioural principles
Behavioural principle
(and indicators)
Description
Leadership and culture
(Leadership, staff
engagement, decision
making, situational
awareness, innovation and
creativity)
A resilient organisation:
• develops an organisational mind-set/culture of enthusiasm for challenges, agility,
flexibility, adaptive capacity, innovation and taking opportunity
• fosters the above through developing trust, clear purpose and empowerment of
employees
• promotes a consistent and transparent organisational commitment to a resilience
culture, values and vision, including a belief of ‘one in – all in’
• encourages increased personal resilience by employees
• has board members and senior executives who engage and provide leadership
appropriate to their position on organisational resilience.
Networks
(Breaking silos, leveraging
knowledge, effective
partnerships, internal
resources)
A resilient organisation:
• establishes relationships, mutual aid arrangements and regulatory partnerships
• understands an organisation’s community interconnectedness and its vulnerabilities
across all aspects of supply chains and distribution networks
• promotes open communication and mitigation of internal/external silos.
Change ready
(Planning strategies, unity
of purpose, proactive
posture, stress testing
plans, innovation and
creativity)
A resilient organisation:
• promotes proactive anticipation and preparation for future challenges
• develops a forewarning of disruption threats and their effects through sourcing a
diversity of views, increasing sensitivity and alertness, and understanding social
vulnerability
• promotes empowered and broadly embraced organisational and individual self-
efficacy, as well as enthusiasm for finding effective solutions to complex challenges
• promotes requisite decision making using both rational and intuitive abilities
• promotes critical reflective learning, lesson retention, knowledge sharing and
continuous improvement.
Source: Resilient Organisations (2012)
4.3.2.3 Summary of chosen resilience principles
To conclude this section, the following broad principles have been summarised which encompass the
views of the various authors across both technical and organisational dimensions, and which are proposed
to form the basis of the framework to measure the resilience of the transport system.
From a technical perspective, Bruneau’s principles of robustness and redundancy are considered to
broadly encapsulate the range of ideas proposed by other authors, while the concept of ‘safe-to-fail’
proposed by Park et al and Snowden is included as a third technical principle. The concept of
‘independent’ as proposed by Foster (or ‘autonomous’) has not been included explicitly as a technical
principle. For transport infrastructure, this may, in theory, be applicable to powered systems (eg lights)
which could be powered by independent supplies; however, it is suggested (for practical reasons) that the
provision of independent supplies be considered instead in a back-up context as ‘redundancy.
Measuring the resilience of transport infrastructure
30
From an organisational perspective, the three principles developed by Resilient Organisations have been
adopted. These are considered to broadly encompass the principles developed by others, as discussed
above.
Table 4.4 Proposed principles of resilience for the transport system
Dimension Principle Definition and justification
T
e
c
h
n
i
c
a
l
Robustness Strength, or the ability of elements, systems and other units of analysis, to
withstand a given level of stress or demand without suffering degradation or loss
of function (Bruneau et al 2003).
Redundancy The extent to which elements, systems, or other infrastructure units exist that are
substitutable, ie capable of satisfying functional requirements in the event of
disruption, degradation, or loss of functionality (Bruneau et al 2003). For
simplification, this is assumed to include considerations of ‘diverse’ and ‘reserve
capacity’. The concept of ‘independent/autonomous’ is included here, only in the
context of back-up provision, as discussed above.
Safe-to-fail The extent to which innovative design approaches are developed, allowing (where
relevant) controlled, planned failure during unpredicted conditions, recognising
that the possibility of failure can never be eliminated. This may involve new
approaches to design, to complement traditional, incremental risk-based design
(Park et al 2013).
O
r
g
a
n
i
s
a
t
i
o
n
a
l
Change readiness* The ability to sense and anticipate hazards, identify problems and failures, and to
develop a forewarning of disruption threats and their effects through sourcing a
diversity of views, increasing alertness, and understanding social vulnerability
(Resilient Organisations 2012). Also involves the ability to adapt (either via
redesign or planning) and learn from the success or failure of previous adaptive
strategies (Park et al 2013). This learning is also conceptualised by Manyena et al
(2011) who in their ‘bounce-forward’ idea of resilience, identify moving from
single-loop or error-corrective learning, to double-loop, organisational learning,
where the values, assumptions and policies that led to the actions in the first place
are questioned.
The capacity to mobilise resources when conditions exist that threaten to disrupt
some element, system, or other unit of analysis; resourcefulness can be further
conceptualised as consisting of the ability to apply material (ie monetary, physical,
technological, and informational) and human resources to meet established
priorities and achieve goals (Bruneau et al 2003).
Networks The ability to establish relationships, mutual aid arrangements and regulatory
partnerships, understand interconnectedness and vulnerabilities across all aspects
of supply chains and distribution networks, and; promote open communication
and mitigation of internal/external silos (Resilient Organisations 2012).
Leadership and
culture
The ability to develop an organisational mind-set/culture of enthusiasm for
challenges, agility, flexibility, adaptive capacity, innovation and taking opportunity
(Resilient Organisations 2012).
*Readiness encompasses the change-ready concepts developed by Resilient Organisations (2012), along with the
concept of ‘resourcefulness’ developed by Bruneau et al (2003) and Park et al (2013).
4 What is resilience?
31
4.4 Summary
4.4.1 Main points
The NIP resilience definition is considered appropriate: ‘The concept of resilience is wider than natural
disasters and covers the capacity of public, private and civic sectors to withstand disruption, absorb
disturbance, act effectively in a crisis, adapt to changing conditions, including climate change, and grow
over time’ (NIU 2011).
The NIP attributes are considered relevant; however, we do not suggest they be used to categorise
resilience dimensions and principles. In subsequent sections, the NIP attributes are mapped to the chosen
framework principles for completeness.
It is suggested that the broad dimensions of technical and organisational be used, along with the
principles of robustness, redundancy, safe-to-fail, change readiness, networks, leadership and culture.
4.4.2 Relevance to framework development
The framework has been built around the broad dimensions as follows:
• technical (robustness, redundancy, safe-to-fail)
• organisational (change readiness, networks, leadership and culture).
Measuring the resilience of transport infrastructure
32
5 How can we measure resilience?
As illustrated in figure 4.3, measures for resilience can be distilled from an analysis of dimensions and
principles. In general terms, measures need to be broad enough to allow application across a variety of
scales, including transport modes. They also need to be transparent and quantifiable (although, this may
be in a relative sense as opposed to being an exact determination).
Past studies have fallen generally into two groups – those which develop a conceptual (qualitative)
framework for measuring resilience, and those which have attempted to develop quantitative metrics
(indices) through more detailed analysis and modelling. We also note the difference between frameworks
that assess resilience after a hazard event, and those that assess resilience before an event.
Initially, however, we explore the question ‘resilience to what?’ We discuss what types of hazards are
relevant and how a resilience assessment could consider consequence as opposed to the hazard itself.
5.1 Resilience to what?
As discussed in section 4.2, there is a wide range of hazards, hazard types and failure modes that could
affect a given piece of infrastructure or the transportation network. However, a resilience assessment also
requires an awareness that the hazard itself may be unpredictable (Park et al 2013) and the organisation
needs to think beyond typical disaster scenarios (Brunsdon and Dalziell 2005).
As such, it is useful to move from consideration of hazards (either via probability or scenario analysis) to
consideration of consequences which specifically relate to the loss of service as well as other impacts.
These consequences can relate to a non-specified hazard event, which could apply to any (or all) hazard
types. Brunsdon and Dalziell (2005) provide some consequence scenarios which are considered applicable
and have been adapted for the transport context:
• Regional event: significant physical damage to transport infrastructure, coupled with severe
disruptions to other lifeline services such as electricity, water and telecommunications. An example of
this type of event may be a major earthquake or flood.
• Localised event: a transport-specific incident resulting in loss of life, severe disruption to normal
operations and reputation impacts. The intense focus of media and regulatory agencies requires the
organisation to focus on managing stakeholder perception as well as the physical response and
recovery from the event. Examples may be a collapse of a transport structure, or a hazardous spill
affecting the immediate locality.
• Societal event: a societal event which may cause unexpected impacts or demand on the transport
system. In this case, all physical infrastructure is intact; however, the transport system is unable to cope
with demand. Examples may include: 1) a surge in traffic demand due to a specific event, or a major
gathering of people, 2) growth in demand over time, 3) growth in public transport demand due to, say,
fuel price rises, 4) an illness pandemic (eg influenza or SARS), meaning operational staff are unavailable.
• Distal event: impacts transport operations through key suppliers or interdependencies. This
consequence scenario can identify the ways the transport system and related organisations may be
affected through its networks of inter-organisational relationships. Examples may be the failure of a
key dependent utility (power, telecommunications, water), failure of a key supplier, or an international
shortage of key resources.
5 How can we measure resilience?
33
Note that such an approach to considering the consequences of unpredictable events should not
necessarily replace an assessment of known (or predictable) hazards using a more standard risk-based
approach.
There may be certain situations where a specific hazard assessment would be appropriate, for example,
where critical assets or sections of network are required to be assessed and hazards are well understood.
In these cases both approaches are required within the overall resilience framework. These have been
distinguished into two categories called ‘all-hazards’ and ‘specific-hazard’.
5.1.1 An all-hazards vs specific hazard approach
To summarise the above discussion, we consider there is merit in undertaking both an all-hazards
approach as well as a specific-hazard approach, depending on the context of the evaluation.
An all-hazards approach to resilience would involve a high-level assessment looking at resilience measures
in response to all hazards in general, and would consider a relevant event scenario as detailed above
(regional, local, societal, distal).
A specific-hazard assessment would be more detailed, however, and therefore might be appropriate for
certain critical assets. This would involve identifying the complete range and type of potential scenarios as
described above, and assessing the risk (likelihood and consequence) of them occurring. The resilience
assessment and response could then be tailored accordingly. Appropriate methods could be used to identify
hazards due to known ‘rare events’ and also non-linear modes of failure involving interdependencies.
The following sections outline approaches to measurement of resilience in both a qualitative and
quantitative context, and recommend a preferred approach.
5.2 Conceptual/qualitative frameworks
These frameworks typically remain at a higher level and set out principles (such as those outlined in
section 4.3) from which resilience can be assessed. Some examples are described below.
Bruneau et al (2003) developed a range of performance criteria (measurement categories) relating to
seismic resilience. Measures were developed specifically for each dimension (TOSE) and related to each
principle (robustness, redundancy, resourcefulness and rapidity) as summarised in table 5.1.
Table 5.1 Seismic resilience measures example
Performance criteria
Performance measures Robustness Redundancy Resourcefulness Rapidity
Technical Damage avoidance
and continued
service provision
Backup/duplicate
systems, equipment
and supplies
Diagnostic and damage
detection technologies
and methodologies
Optimising time to
return to pre-event
functional levels
Organisational Continued ability to
carry out designated
functions
Backup resources to
sustain operations
(eg alternative sites)
Plans and resources to
cope with damage and
disruption (eg mutual
aid, emergency plans,
decision support
systems)
Minimise time
needed to restore
services and
perform key
response tasks
Social Avoidance of
casualties and
disruption in the
community
Alternative means of
providing for
community needs
Plans and resources to
meet community needs
Optimising time to
return to pre-event
functional levels
Measuring the resilience of transport infrastructure
34
Performance criteria
Performance measures Robustness Redundancy Resourcefulness Rapidity
Economic Avoidance of direct
and indirect
economic losses
Untapped or excess
economic capacity
(eg inventories,
suppliers)
Stabilising measures (eg
capacity enhancement
and demand
modifications, external
assistance, optimising
recovery strategies)
Optimising time to
return to pre-event
functional levels
Source: Bruneau et al 2003
Brabhaharan (2006) also developed a method to establish ‘performance criteria’ and example metrics by
which elements of the transport system could be measured after an event. These were based on specific
levels of service requirements following hazard events, and performance criteria developed for specific
critical sections of the network by relevant stakeholders. Some example criteria are shown in table 5.2.
These serve as useful example measures; however, it is noted that these apply to a post-event situation.
Similar, qualitative measures could be developed for use before an event.
Table 5.2 Example performance criteria
Service provided Priority/criticality of
relevant road link
Level of service Measure
1a. Temporary access to
emergency services for
emergency service vehicles
Very high Restore temporary road access
to hospitals and emergency
centres.
Within two hours
1b. Temporary access to
emergency services for
emergency service vehicles
High Restore temporary road access
to hospitals and emergency
centres identified by the
district health board
Within two days
2a. Access to lifeline utilities N/A (all are assumed
equal)
Restore 4x4 road access to
power, water and
telecommunication utilities for
inspection and repair.
Within three days.
3a. Network availability High Re-open one lane for heavy
trucks and buses
Within 24 hrs.
3b. Network availability Medium Re-open one lane for heavy
trucks and buses
Within 36 hrs.
3c. Network availability Low Re-open one lane for heavy
trucks and buses
Within one week
Source: Brabhaharan (2006)
Other examples of conceptual transport-related frameworks include those developed by Heaslip et al
(2009), Murray-Tuite (2006), Mostashari et al (2009). All of these are qualitative in nature and propose a
range of subjective criteria to assess.
Dantas and Giovinazzi (2010) developed a benchmarking framework to measure the readiness of road
controlling authorities to meet their obligations under the Civil Defence and Emergency Management Act
2002. The self-assessment tool developed, included a set of key performance indicators, which are
representative of the critical success factors in emergency management, and benchmarked performance in
relation to the 4Rs (reduction, readiness, response and recovery).
5 How can we measure resilience?
35
Lee et al (2013) developed a framework and survey tool for organisations to use to identify their strengths
and weaknesses and to develop and evaluate the effectiveness of their resilience strategies and
investments. The survey consisted of a range of questions across 13 indicators which are shown as
subsets within table 4.3.
5.3 Quantitative approaches
A number of authors have developed detailed quantitative methods for measuring the resilience of specific
networks. In many cases these have produced a ‘resilience index’ resulting from the modelling of
networks and possible failure modes.
In general terms, many of the methods set out to a) evaluate the failures in levels of service due to the
impact of an event, b) evaluate the time to restore an acceptable level of service to a network and c)
compare the recovered system performance as a result of a strategy (intervention) with the system
performance without the strategy.
Approaches used to undertake the analysis vary and include the use of network models, GIS analysis,
fuzzy systems approaches and others. Urena Serulle (2010) summarised a range of previous analyses
undertaken and related field and methodology employed, which is shown in table 5.3.
Table 5.3 Summary of previously proposed quantitative assessments of resilience
Author Field Proposed methodology
Hamad and Kikuchi
(2002)
Transportation
engineering
Developed a measure of traffic congestion based on two
conventional transportation metrics, travel speed and delay.
A fuzzy inference approach was implemented to combine
travel speed and delay into one single index. The result was
a congestion index that ranges from 0 to 1, where 0 is the
best condition and 1 the worst.
Brenkert and Malone
(2004)
Social study Proposed a set of 17 quantitative indicators that allow
comparisons of different levels of localities (regional, states,
cities, etc) in terms of their vulnerability and resilience to
current and changing climate.
Mayunga (2007) Social study Obtained a weighted average of the resilience elements
(social capital, human capital, economic capital, physical
capital and natural capital) to obtain a single community
disaster resilience index.
Heaslip et al (2010) Transportation
engineering
Ten measurable variables were used to define four basic
network performance indexes (network availability, traveller
perception, transportation cost and network accessibility).
These four indexes were then combined using fuzzy
inference logic into a single network service performance
index, which served as a base resilience index.
Source: Serulle 2010
5.4 Recommended measurement approach
Based on the above research of measurement approaches, table 5.4 summarises each type of approach.
Measuring the resilience of transport infrastructure
36
Table 5.4 Summary of qualitative and quantitative measurement approaches
Qualitative approach Quantitative approach
Flexibility Provides a flexible approach that can
be adapted to a range of situations,
scales and conditions.
Is typically applied only at a smaller
geographical scale and at a more
detailed level.
Data requirements Can be applied with complete or
incomplete data sets. Relies on
subjective assessments in many
cases.
Typically requires large, accurate data
sets.
Computational requirements None/minimal. Requires significant computational
effort.
Results A relative, subjective assessment –
often using a ranking scale
Typically delivers a discrete resilience
index or measure by way of network
modelling or fuzzy logic modelling.
Ease of implementation Simple Difficult
Use in targeting resilience
improvements
Useful; however, is very much
related to the design of the
framework, how it is implemented,
and subjectivity of the scores given.
Can be accurate for the network
analysed.
Useful in wider organisational
resilience assessments and
engagement
Yes No
Useful in assessing physical network
asset resilience
Yes Yes
Based on the above, we suggest that a broadly qualitative approach would better suit the Transport
Agency’s requirements for a practical and flexible framework. We note that there may be some
quantitative measures within the overall framework; however, generally speaking, we propose a qualitative
assessment.
The approach will be based around:
• dimensions of resilience – technical and organisational
• principles of resilience – robustness, redundancy, safe-to-fail, readiness, continuous management,
leadership and culture, networks.
5.5 Summary
5.5.1 Main points
Either an ‘all-hazards’ or ‘hazard-specific’ approach could be used for measuring resilience. The latter
would be much more detailed and it may be appropriate in certain situations where specific hazards are
well understood.
Historically, both qualitative and quantitative approaches have been used for measuring resilience.
Quantitative approaches tend to be less flexible, time consuming and appropriate for more narrow
assessments of networks and systems. They are data intensive and can be difficult to implement.
5 How can we measure resilience?
37
Qualitative assessments are, by nature, more subject to interpretation, but are flexible in terms of scale
and context, and can provide wider process and organisational benefits due to the necessary involvement
of operators and managers.
There are also broadly qualitative frameworks which contain measures that are more quantitative in
nature.
5.5.2 Relevance to framework development
A broadly qualitative approach to measuring resilience is proposed, with a range of specific
measures/categories based on the dimensions and principles developed in the previous section.
The framework should be able to be implemented at a general ‘all-hazards’ level or a ‘specific-hazard’
level.
Measuring the resilience of transport infrastructure
38
6 A proposed measurement framework for
transport system resilience
This chapter summarises a proposed practical framework for measuring resilience based on the
dimensions and principles developed in previous sections. For each step, explanation and detail is
provided to justify the chosen approach.
The process described in figure 6.1 includes an initial determination of the context of the resilience
assessment, followed by a detailed assessment using a wide range of resilience measures, which combine
to generate a resilience score from 4 (very high resilience) to 1 (low resilience):
4 Very high resilience – meets all requirements
3 High resilience – acceptable performance in relation to a measure(s), some improvements could be
made
2 Moderate resilience – less than desirable performance and specific improvements should be prioritised
1 Low resilience – poor performance and improvements required.
The following sections describe each of these processes in more detail.
6 A proposed measurement framework for transport network resilience
39
Figure 6.1 Proposed resilience assessment
Measuring the resilience of transport infrastructure
40
6.1 Resilience assessment context
The resilience assessment has been divided into dimensions and principles as determined in chapter 4.
The broad level dimensions used are technical and organisational. Principles of resilience have been taken
as robustness, redundancy, safe-to-fail, change-readiness, networks, and leadership and culture.
Robustness, redundancy and safe-to-fail relate to technical, asset or network considerations while the
remainder relate to the organisational considerations (refer to figure 6.1).
Each of the above four principles has been mapped to the NIP 2011 attributes to ensure that the
framework links to and aligns with the NIU process.
There are a number of cross-cutting themes that influence the context and approach of the resilience
assessment. These are summarised and discussed in the table below.
Table 6.1 Cross-cutting themes
Cross-cutting theme Discussion
All hazards/specific hazard
approach
The assessment can be undertaken in one of two ways:
1 An all-hazards assessment – based on an event due to any (unspecified)
hazard/failure, which could be either known or unknown. The event could
be regional, local, societal or distal (section 5.1).
2 A hazard-specific assessment could be undertaken. This would involve
identifying the relevant known hazard types and assessing the resilience to
each.
Scale of assessment The framework will allow assessment at various scales: regional, network or
asset. Measures have been developed for each and the user can filter the
questions accordingly. Regional assessments could be aggregated to a national
indicator for NIU purposes.
Shock event or stress event The framework will be able to evaluate both short-term shock events (eg
earthquakes and tsunamis) and longer-term stress events (eg climate change
related).
Stress events should be considered as part of a hazard-specific assessment (see
above) and if required, a risk-assessment could be undertaken as well to
understand likelihood and consequence of occurrence.
6.2 Resilience measures
A range of measurement categories are suggested based on the six resilience principles – as discussed in
section 5.2. Within these categories, specific measures have been developed. It is important to note that
each category covers a range of parameters associated with that measure.
The measurement categories are described in table 6.2 and map to the NIP resilience attributes as shown.
Each technical principle has been divided into categories of structural, procedural and interdependencies
as these are thought to encapsulate the main types of relevant measures. Organisational principles have
been divided into categories based on those proposed by Resilient Organisations (2012) and Lee et al
(2013), as well as some additional categories suggested by the authors of this report.
6 A proposed measurement framework for transport network resilience
41
Table 6.2 Summary of measurement categories
Principle Measurement category Description
Technical
Robustness
(NIP attributes: service
delivery, adaptation,
Interdependencies)
Structural Physical measures relating to asset/network design,
maintenance and renewal
Procedural Non-physical measures relating to existence, suitability and
application of design codes, guidelines
Interdependencies This relates to upstream dependencies (refer section 3.2) and
their relative robustness in both a structural and procedural
sense
Redundancy
(NIP attribute: adaptation,
Interdependencies)
Structural Physical measures relating to network redundancy, alternate
routes and modes and backup supplies/resources
Procedural Non-physical measures relating to existence of diversion and
communication plans
Interdependencies
This relates to upstream dependencies and their relative
redundancy in both a structural and procedural sense.
Safe-to-fail
(NIP attribute: adaptation)
Structural The extent to which innovative design approaches are
implemented, allowing (where relevant) controlled failure
during unpredicted conditions. This may complement
traditional, incremental risk-based design (Park et al 2013).
Procedural The extent to which safe-to-fail designs are specified in
design guidelines.
Organisational
Change readiness
(NIP attributes:
community preparedness,
responsibility,
interdependencies,
financial strength,
organisational
performance)
Communication and
warning
This relates to the existence and effectiveness of
communication and warning systems
Information and
technology
This relates to the use of technology to monitor events,
communicate, share data, assess resilience etc.
Insurance This relates to the adequacy of insurances for hazard events.
Internal resources The management and mobilisation of the organisation’s
resources to ensure its ability to operate during business-as-
usual, as well as being able to provide the extra capacity
required during a crisis.
Also relates to ensuring roles and responsibilities of all
internal stakeholders are clear and that coordination is
effective.
Planning strategies The development and evaluation of plans and strategies to
manage vulnerabilities in relation to the business
environment and its stakeholders.
Clear recovery priorities An organisation-wide awareness of what the organisation’s
priorities would be following a crisis, clearly defined at the
organisation level, as well as an understanding of the
organisation’s minimum operating requirements.
Proactive posture A strategic and behavioural readiness to respond to early
warning signals of change in the organisation’s internal and
external environment before they escalate into crisis.
Drills and response
exercises
The participation of staff in simulations or scenarios designed
to practice response arrangements and validate plans.
Measuring the resilience of transport infrastructure
42
Principle Measurement category Description
Funding Extent to which funding is available for all elements of
resilience planning including technical and organisational.
Adaptation Constant vigilance and situation awareness (see below) allows
adaptation strategies to be developed. These may be
procedural/planning focused/organisational or technical
(increased robustness, redundancy, or designing for ‘safe-to-
fail’ modes).
Learning Past actions and adaptation strategies are observed and
evaluated in terms of their success in mitigating hazards.
Appropriateness of actions can be assessed and iterations
and changes made.
Networks
(NIP attributes:
interdependencies)
Breaking silos Minimisation of divisive social, cultural and behavioral
barriers, which are most often manifested as communication
barriers creating disjointed, disconnected and detrimental
ways of working.
Leveraging knowledge
(internal and external)
Critical information is stored in a number of formats and
locations and staff have access to expert opinions when
needed. Roles are shared and staff are trained so that
someone will always be able to fill key roles.
Effective partnerships
(external)
An understanding of the relationships and resources the
organisation might need to access from other organisations
during a crisis, and planning and management to ensure this
access. Also relates to clear coordination and understanding
between organisations, and clarity of roles and
responsibilities.
Leadership and culture
(NIP attributes:
organisational
performance)
Situation awareness
(sensing and anticipation)
Staff are encouraged to be vigilant about the organisation, its
performance and potential problems. Staff are rewarded for
sharing good and bad news about the organisation. Early
warning signals are quickly reported to organisational
leaders. Newly incorporated knowledge gained from vigilance
is used to foresee/anticipate crises. This can be used to
develop adaptation strategies.
Leadership Strong crisis leadership to provide good management and
decision making during times of crisis, as well as continuous
evaluation of strategies and work programs against
organisational goals.
Staff engagement and
involvement
The engagement and involvement of staff who understand
the link between their work, the organisation’s resilience, and
its long-term success. Staff are empowered and use their
skills to solve problems.
Decision-making authority Staff have the appropriate authority to make decisions related
to their work and authority is clearly delegated to enable a
crisis response. Highly skilled staff are involved in, or are
able to make, decisions where their specific knowledge adds
significant value, or where their involvement will aid
implementation.
Innovation and creativity Staff are encouraged and rewarded for using their knowledge
in novel ways to solve new and existing problems and for
utilising innovative and creative approaches to developing
solutions.
6 A proposed measurement framework for transport network resilience
43
A detailed database (spreadsheet) has been developed which describes measurements and captures scores
on a scale of 4 (very high level of resilience) to 1 (low resilience). Some example measures for ‘robustness’
are shown in figure 6.2 below, with the complete lists contained in appendix B. The measures can then be
weighted at the discretion of the user to give an aggregate score for a principle (eg robustness) or
dimension (eg technical), or overall.
A summary ‘dashboard’ allows the user to view the various scores and weightings used.
Figure 6.2 Example of resilience measures (for the ‘robustness’ principle)
ROBUSTNESS
Weighted robustness score 2.3
Category Measure Measurement Measurement scale Individual
score
Category
average
Weighting
(%)
Weighted
score
Structural
Maintenance Processes exist to maintain critical
infrastructure and ensure integrity
and operability – as per documented
standards, policies & asset
management plans (eg roads
maintained, flood banks maintained,
stormwater systems are not blocked.
Should prioritise critical assets as
identified.
4 – Audited annual inspection process for critical
assets and corrective maintenance completed when
required.
3 – Non-audited annual inspection process for critical
assets and corrective maintenance completed when
required.
2 – Ad hoc inspections or corrective maintenance
completed, but with delays/backlog.
1 – No inspections or corrective maintenance not
completed.
3.0
2.8 33.33% 94.4
Renewal Evidence that planning for asset
renewal and upgrades to improve
resilience into system networks exist
and are implemented.
4 – Renewal and upgrade plans exist for critical assets,
are linked to resilience, and are reviewed, updated and
implemented.
3 – Renewal and upgrade plans exist for critical assets
and are linked to resilience, however no evidence that
they are followed.
2 – Plan is not linked to resilience and an ad hoc
approach is undertaken.
1 – No plan exists and no proactive renewal or
upgrades of assets.
4.0
Design
Percentage of assets that are at or
below current codes
4 – 80% are at or above current codes
3 – 50-80% are at or above current codes
2 – 20-50% are at or above current codes
1 – Nearly all are below current codes
3.0
Assessment of general condition of
critical assets across region
4 – 80% are considered good condition
3 – 50-80% are considered good condition
2 – 20-50% are considered good condition
1 – Nearly all poor condition
3.0
Percentage of assets that are in
zones/areas known to have exposure
to hazards
4 – 50% are moderately
exposed
2 – 50-80% are highly exposed
1 – 80% are highly exposed to a hazard
2.0
Percentage of critical assets with
additional capacity over and above
normal demand capacity
4 – 80%+ of critical assets have >50% spare capacity
available
3 – 50-80% of critical assets have >50% available
2 – 20-50% of critical assets have >50% spare capacity
1 – 0-20% have spare capacity.
2.0
In summary, the approach to undertaking the resilience assessment is as follows:
1 Determine the context of the assessment:
a all-hazards or specific hazards (including shock or stress event, rare events etc)
b scale: asset/network/regional context
c shock or stress event.
2 Undertake the assessment using the questions relative to the context above and select scores for
each.
3 Apply weightings to the scores, as required.
4 This will generate resilience scores for categories, principles and dimensions and a total score.
Measuring the resilience of transport infrastructure
44
As a stand-alone assessment, the resilience measurement framework can be applied to generate a relative
score that could be used to compare resilience across assets/networks or regions. However, to provide
additional rigour, other steps could be applied. This is discussed in chapter 7.
6.2.1 Application of weightings
The resilience measurement framework consists of a range of questions across the categories shown in
figure 6.1. Once the relevant questions have been answered, weightings can be applied at the category,
principle or dimension level. These weightings are a percentage and must add to 100% across each group.
The weightings allow the user to place importance to (say) one principle over another. For example, one
may determine that ‘robustness’ is more important than ‘redundancy’ or ‘safe-to-fail’ and as such, allocate
a weighting of 40%:30%:30%.
It is important to note that the weightings are subjective and will be based on user preference. In all
instances, the individual scores for each question can be viewed and interrogated to determine reasons
behind a specific principle or dimension score.
Further guidance on the use of the framework is provided in appendix F.
6.3 Summary
6.3.1 Main points
The resilience measurement framework relates to the dimensions, principles and categories outlined in
previous sections. Specific measures for each category have been developed and are included in appendix B.
Each measure is scored from 4 (very high resilience) to 1 (low resilience), and weightings can be applied at
the category, principle and dimension level to generate aggregate scores if required.
The approach can be applied at various scales and to an ‘all-hazards’ or ‘hazard-specific’ context.
7 Implementation of the framework
45
7 Implementation of the framework
As mentioned in chapter 6, the resilience assessment could be applied as a stand-alone assessment for a
particular asset or region.
However, in order to implement the measurement framework in a systematic manner, additional steps
could be incorporated to determine priorities for intervention. This would include determining:
1 Which infrastructure should be assessed for resilience?
2 What level of resilience is appropriate for a given asset/network?
In order to answer these questions, we need to have an understanding of the criticality of a given asset,
and, if required, an understanding of the risk of a particular hazard occurring. Note, this links directly with
the choice of whether a general ‘all-hazards’ or a ‘hazard-specific’ assessment is chosen.
Figures 7.1 and 7.2 summarise the two alternative approaches.
Figure 7.1 All-hazards: criticality and resilience assessment
Figure 7.2 Hazard specific: detailed risk assessment and resilience assessment
The all-hazards approach would involve an assessment of criticality to determine which assets should be
focused on for the resilience assessment. The related questions within the measurement framework
(appendix B) would be those applicable across all hazard types (or, in other words, as the consequence of
a regional, local, societal or distal event – refer section 5.1). The criticality assessment would identify
which assets merited a certain ‘desired’ level of resilience, and then following a resilience assessment for
these assets, related improvements or interventions could be targeted. The translation from criticality to
‘desired’ level of resilience is summarised in table 7.1.
Table 7.1 Example translation of criticality score to ‘desired’ level of resilience
Criticality score Desired level of resilience
Highly critical Very high (4)
Medium High (3)
Low Moderate (2)
Not critical Low (1)
If further detail was required, a hazard-specific assessment could be undertaken. This would require
understanding which types of hazards would be relevant and their associated likelihoods. In this case, the
output of the risk-assessment would determine the ‘desired’ level of resilience.
Criticality
assessment
Resilience
assessment
Improvements
/ intervention
‘Desired’
resilience
Criticality
assessment
Risk
assessment
Resilience
assessment
Improvements
/ intervention
‘Desired’
resilience
Measuring the resilience of transport infrastructure
46
The Transport Agency currently has a state highway classification system that could be utilised to
determine criticality of assets. Rail system operators and local authorities may also have similar methods
for determining criticality. There are, however, a range of additional considerations that can be
incorporated into a criticality assessment, relating to operational considerations, interdependencies and
specific user/community requirements. More information on this is provided in appendix D.
The Transport Agency also has an established risk assessment approach based on the joint
Australian/New Zealand standard AS/NZS 31000:2009, which could be utilised to determine an overall risk
score relating to the likelihood and consequence of a particular hazard occurring (refer to appendix A for
further detail). Other transport system operators may also have similar approaches.
In order to link to the resilience assessment, the risk assessment would need to specifically address:
1 The likelihood of a particular hazard occurring in a given location/region and the likelihood that it
would impact on a given asset.
2 The consequence of failure of the asset, which would be related to the criticality assessment (ie a
critical asset would have a high consequence if it fails).
The resultant risk score derived from a risk assessment could then translate to a ‘desired’ level of
resilience, as illustrated in table 7.2 (example).
Table 7.2 Example translation of risk score to ‘desired’ level of resilience
Risk score (Transport Agency tool) Desired level of resilience
4 (Extreme) Very high (4)
3 (High) High (3)
2 (Moderate) Moderate (2)
1 (Low) Low (1)
As outlined above, a risk assessment would be undertaken as part of a hazard-specific assessment. In this
case, specific attention would need to be given to the types of hazards and failure causes/modes that may
eventuate (refer sections 4.2 and 5.1).
Types of hazards would include, by definition, known hazards and also, where relevant, an assessment of
‘rare event’ possibilities. This assessment could include a range of activities with experienced operational
staff to:
• identify linkages and interdependencies
• think the unthinkable in terms of rare events and failure modes
• consider the combinations of events that might occur
• consider what is happening elsewhere (horizon scanning)
• be more creative in risk identification and identify events that might be known by others but a ‘black
swan’ to the Transport Agency.
Table 7.3 summarises the ranges of scales of application and the suggested relevant approaches which
could be implemented.
7 Implementation of the framework
47
Table 7.3 Approaches to implementation
Scale Suggested approach Application
Asset 1 Hazard-specific: would involve assessing
the resilience of an asset, and comparing
with a desired level based on risk.
2 All-hazards: would involve assessing the
resilience of an asset, and comparing
with a desired level based on criticality
of the asset.
1 This would enable actions and
interventions to be prioritised across
assets in relation to specific identified
hazards.
2 This would enable actions and
interventions to be prioritised across
assets more generally and in relation
to ‘all hazards’.
Network/route 1 Hazard-specific: would involve assessing
resilience of various elements within the
network/route, and comparing with a
desired level based on risk.
2 All-hazards: would involve assessing
resilience of various elements within the
network/route to ‘all-hazards’, and
comparing with a desired level based on
criticality of the network/route.
1 This would enable actions and
interventions to be prioritised across
the broader transport system in
relation to specific identified hazards.
2 This would enable actions and
interventions to be prioritised across
the broader transport system in
relation to ‘all-hazards’.
Regional* 1 Hazard-specific: would involve assessing
resilience of various critical elements
within the region, and developing a
stand-alone score.
2 All-hazards: would involve assessing
resilience of various critical elements
within the region to ‘all-hazards’, and
developing a stand-alone score.
1 This would enable regions to be
compared, and actions and
interventions to be prioritised across
regions in relation to specific identified
hazards.
2 This would enable regions to be
compared, and actions and
interventions to be prioritised across
regions in relation to ‘all hazards’.
(A national assessment could be generated
by aggregating regional scores that could
then be utilised by the NIU.)
*An alternative approach to assessment at a regional level would be to undertake individual asset or network
assessments, and aggregate individual resilience scores into a regional score. This would require more detail, and it is
suggested that the approach above is implemented in the first instance.
7.1 Summary
The resilience measurement framework could be applied as a standalone assessment; however, in practice
the framework should be implemented either via an ‘all-hazards’ approach or a ‘hazard-specific’ approach
– either at an asset, network or regional scale.
The ‘all-hazards’ approach would involve an initial criticality assessment.
The ‘hazard-specific’ approach would involve a risk assessment and a more detailed understanding of
potential hazards and failure possibilities.
It is important to emphasise here that this is a resilience assessment tool and not a risk assessment tool,
although risk does form an important part of implementation.
Measuring the resilience of transport infrastructure
48
8 Example assessments
This section covers two high level examples through which the measurement framework is illustrated. The
examples are fictitious, but serve to illustrate the application of the framework.
8.1 Regional all-hazard assessment
Table 8.1 summarises the assessment approach. The detailed questions for the assessment are included
within appendix B.
Table 8.1 Example all-hazard assessment
Assessment context
and approach:
Regional, all hazard, pre-event.
Assessment to be undertaken initially as a stand-alone assessment.
Assessment
example:
Regional event (significant physical damage to transport infrastructure, coupled with severe
disruptions to other lifeline services such as electricity, water and telecommunications).
[An organisation that has experienced a few major disasters some time ago and has some
resilience responses in place but is just starting to re-invigorate its resilience preparation
and integration].
Technical resilience
assessment:
Robustness: Robustness is assessed via a series of measures across the categories of
structural, procedural and interdependencies. An example assessment is given below. Note:
all categories are weighted equally.
Structural: Across the five measures, the average score is 2.8, which is ‘moderate’.
[Rationale: maintenance and renewal of assets is acceptable, however most critical assets
(such as bridges) are not up to current design code levels, as they were built in the 1960’s].
Procedural: Across the one measure, the average score is 2.0, which is ‘moderate’.
[Rationale: design codes and guidelines do not adequately address resilience issues].
Interdependencies: Across the two measures, the average score is 2.0, which is ‘moderate’.
[Rationale: planning for resilience by interdependent utilities is less than adequate].
Overall robustness score of 2.3 (moderate).
Redundancy: Redundancy is assessed via a series of measures across the categories of
structural, procedural and interdependencies. An example is given below. Note: all
categories are weighted equally.
Structural: Across the four measures, the average score is 2.0, which is ‘moderate’.
[Rationale: indicates that availability and capacity of alternative routes and modes is less
than adequate].
Procedural: Across the one measure, the average score is 2.0, which is ‘moderate’.
[Rationale: indicates planning for diversions to alternate routes is less than adequate].
Interdependencies: Across the two measures, the average score is 2.0, which is ‘moderate’.
[Rationale: supplier awareness of redundancy issues, and implementation of improvements
is less than adequate].
Overall redundancy score of 2.0 (moderate).
Safe-to-fail: Safe-to-fail is assessed via two single measures. An example is given below.
Note: all categories are weighted equally.
Structural: Across this measure, the score is 2.0, which is ‘moderate’. [Rationale: indicates
safe-to-fail design and planning is less than adequate].
Procedural: Across this measure, the score is 2.0, which is ‘moderate’. [Rationale: indicates
safe-to-fail design and planning is less than adequate].
Overall safe-to-fail score of 2.0 (moderate).
Score 4 3 2 1
Score 4 3 2 1
Score 4 3 2 1
8 Example assessments
49
Organisational
resilience
assessment:
Change readiness: Change readiness is assessed across 11 categories as summarised in
table 6.2. A range of measures are assessed for each category – as summarised below:
Note: all categories are weighted equally.
Communication and warning 1.5 (note poor communication and warning)
Information and technology 2.0
Insurance 3.0 (good insurance cover)
Internal resources 2.3
Planning strategies 2.1
Clear recovery priorities 2.5
Proactive posture 2.0
Drills and response exercises 3.2 (note well prepared)
Funding 1.7 (note poor funding)
Situation awareness (sensing) 1.5 (note poor ability to sense new hazards)
Learning 2.5
Overall change readiness score of 2.7 (high).
Networks: Networks are assessed across three categories as summarised in table 6.2. A
range of measures are assessed for each category – as summarised below: Note: all
categories are weighted equally.
Breaking silos 3.0 (good score)
Leveraging knowledge (internal and external) 1.5 (poor score)
Effective partnerships (external) 2. 1
Overall networks score of 2.2 (moderate).
Leadership and culture: Leadership and culture is assessed across four categories as
summarised in table 6.2. A range of measures are assessed for each category – as
summarised below: Note: all categories are weighted equally.
Leadership 3.0 (good score)
Staff engagement and involvement 3.0 (good score)
Decision making authority 3.0 (good score)
Innovation and creativity 2.0
Overall leadership score of 2.8 (high).
Summary As a result of the assessment the following aggregate scores are produced:
Technical: 2.1, Organisational: 2.6
Overall resilience score: 2.3
While both scores are near the middle of the range, this indicates the priority may be to
invest in the technical response. However, there are significant areas for improvement
across both technical and organisational.
While this is a fictitious example, it clearly illustrates the usefulness in being able to:
1 Interrogate individual scores to explain/understand the outcomes
2 Clearly communicate areas for improvement
3 Generate an overall resilience score to give a broad understanding.
8.2 Asset, hazard-specific assessment
In order to illustrate an example relevant to a particular asset, and for a given hazard type, it is useful to
expand on the above example. We have not presented an entirely new assessment, as this would give little
value. We have, however discussed what the additional steps and considerations would be in this situation.
Score 4 3 2 1
Score 4 3 2 1
Score 4 3 2 1
Score 4 3 2 1
Measuring the resilience of transport infrastructure
50
Table 8.2 Example hazard-specific assessment
Assessment context
and approach
Asset, hazard-specific, pre event.
Assessment to be undertaken as per figure 7.2, and consisting of an initial criticality and
risk assessment to determine ‘desired’ level of resilience, followed by resilience
assessment.
Assessment example Major connecting road to port, determined as a highly critical asset. Hazard to assess is
flooding.
Risk assessment Risk implication of flooding includes:
• damage to pavement or other assets (eg embankments, structures, drainage assets
etc)
• transport delays of goods from facilities to the export port, as well as delays to
general traffic
• short-term loss of port access leading to increased service disruptions due to
increased maintenance regimes
• back-up of goods that cannot leave or access the port generating a financial burden
on importers and exporters
• increased coastal flooding from extreme rainfall events and sea level rise as water
cannot drain into the sea due to outfall pipes being below sea level.
Risk assessment as per the Transport Agency risk tool generates an ‘extreme risk’ score
(requires urgent attention). Therefore a ‘very high’ level of resilience is required.
Technical resilience
assessment
A similar assessment would be undertaken as per the previous example; however,
questions would relate to the specific asset in question, and the specific hazard (flooding)
being assessed. No further detail is provided.
Organisational
resilience assessment
A similar assessment would be undertaken as per the previous example; however,
questions would relate to the organisation’s ability to respond to the specific hazard
(flooding) being assessed, and the specific type and location of the asset. No further
detail is provided.
Summary As a result of the assessment it is assumed an identical score is produced as follows:
Overall resilience score: 2.3
The desired ‘very high’ level of resilience is 4.0, and therefore interventions are required
to improve the score, both in a technical and organisational sense.
As discussed above, interrogation of the individual scores will identify where
improvements can be made.
Score 4 3 2 1
9 Conclusions and future work
51
9 Conclusions and recommendations
9.1 Conclusions
The Transport Agency has a key interest in ensuring that transport infrastructure assets and services
function continually and safely. This interest has led to a specific focus on the concept of resilience and
how this can be defined, measured and improved across the transport system.
In a transport context, societies rely on transportation networks for their activities. The ability of the
transport system to function during adverse conditions and quickly recover to acceptable levels of service
after an event is fundamental to the wellbeing of communities.
The framework developed through this study gives effect to the guiding principle of resilience within the
NIP and links to the NIP resilience attributes developed by the Treasury. It is applicable to the broad land
transport system (road and rail), and allows assessments at various scales (asset/network/region). The
assessment can be applied as both a non-specific ‘all-hazards’ approach or a ‘hazard-specific’ approach.
A key difference between these approaches is the incorporation of a risk assessment component. An all-
hazards approach accounts for the unpredictability of future extreme events and emergent hazards. As
these events are inherently unknowable, a likelihood of occurrence cannot be estimated, and as such, a
risk assessment is not applicable. However, if specific hazards are well known and are required to be
assessed, then a risk-based assessment can be undertaken.
A broadly qualitative framework was developed, which provides the user with a flexible, simple and
practical tool to understand resilience of the transport system and as a result, prioritise investment
decisions. The framework utilises the following dimensions and principles, developed from a variety of
sources, and which encapsulate the key considerations both from a technical and, importantly, an
organisational point of view.
Dimension Principle
Technical Robustness, redundancy, safe-to-fail
Organisational Change readiness, networks, leadership and culture
The assessment process consists of a range of questions within each principle, and to which the user can
assign scores. Each individual score can be weighted at the discretion of the user, and scores aggregated
to the principle or dimension level if required. In addition, if applied at a regional level, the overall
regional scores could be further summarised to give a picture of national resilience for use within NIU
reporting.
Due to project constraints, detailed real-scenario testing of the framework was not undertaken (instead, a
hypothetical example assessment was provided to illustrate the application of the framework). Specific
operator knowledge of assets and the relevant organisations would be required to meaningfully undertake
an assessment and it is recommended that this be considered as a subsequent stage.
9.2 Recommendations
A number of other improvements are suggested that may enhance resilience understanding and aid in the
implementation of the framework. These are:
Measuring the resilience of transport infrastructure
52
• Identify ways to improve understanding of critical infrastructure and factors which may determine
criticality - from both an economic and societal point of view. These may include factors such as:
providing access to critical infrastructure nodes (eg control centres or substations), access to critical
community facilities (eg hospitals), or sections of road that have no alternative routes.
• Undertake further economic and engineering research to better understand and quantify a suitable
level of investment in technical (structural) resilience. This is generally where significant capital
expenditure is required, and is difficult to justify when funding is limited. A recent Australian study
Building our nation’s resilience to natural disasters (Deloitte 2013) compared investment in pre-
disaster resilience with post-disaster expenditure on relief and recovery – through a number of case
studies. General findings showed that for a vast majority of pre-disaster resilience initiatives, the
benefit–cost ratio was favourable, highlighting that the policy response to building resilience to
natural disasters must focus on prevention. Similar work is required in a New Zealand context.
• Improve understanding of linkages between resilience and sustainability. To date, conversations
around infrastructure resilience have occurred largely in isolation of those which occur around
sustainability. However, it is clear that many resilience measures are also measures that may be
implemented to improve sustainability (such as green infrastructure, decentralised systems). Bringing
the two fields of study together may lead to improved outcomes for both and should be explored
further in both an academic and practical sense.
10 References
53
10 References
AECOM, Arcadis, US Department of Transportation, Metropolitan Transportation Commission, Caltrans,
Bay Conservation and Development Commission (2011) Adapting to rising tides: transportation
vulnerability and risk assessment pilot project. Briefing book, November 2011. Accessed 23 November
2013. www.mtc.ca.gov/planning/climate/Rising_Tides_Briefing_Book.pdf
Allenby, B and J Fink (2005) Toward inherently secure and resilient societies. Science 309, no.5737: 1034–
1036.
Anderies JM, AA Rodriguez, MA Janssen and O Cifdaloz (2007) Panaceas, uncertainty, and the robust
control framework in sustainability science. In Proceedings of the National Academy of Sciences of the
United States of America 104, no.39: 15194–15199.
Auckland Engineering Lifelines Project (2012) Assessing Auckland’s infrastructure vulnerability to natural
and man-made hazards and developing measures to reduce our region’s vulnerability. Auckland
Engineering Lifelines Group report, version 1.0.
Australian Greenhouse Office (AGO) (2006) Climate change impacts and risk management. A guide for
business and government. Canberra: Department of the Environment and Heritage, Australian
Greenhouse Office.
Beatley, T (1998) The vision of sustainable communities. Chapter 8 in Cooperating with nature. R Burby
(Ed). Washington, DC: National Academy Press, Joseph Henry Press.
Berger, A, C Kousky and R Zeckhauser (2008) Obstacles to clear thinking about natural disasters: five
lessons for policy. Pp73–94 in Risking house and home: disasters, cities, public policy. JM Quigley and
LA Rosenthal (Eds). Berkeley, CA: Berkeley Public Policy Press.
Brabhaharan, P (2006) Recent advances in improving the resilience of road networks. New Zealand Society
of Earthquake Engineering Conference 2006.
Brabhaharan, P, MJ Fleming and R Lynch (2001) Natural hazard risk management for road networks. Part I:
Risk management strategies. Transfund New Zealand research report 217. 75pp.
Brabhaharan, P, LM Wiles and S Frietag (2006) Natural hazard road risk management. Part III: Performance
criteria. Land Transport New Zealand research report 296. 126pp.
Brenkert, A and E Malone (2004) Modeling vulnerability and resilience to climate change: a case study of
India and Indian States. Climatic Change 72: 57–102.
Brundson, D and E Dalziell (2005) Making Organisations Resilient: Understanding the Reality of the
Challenge. Pp27–34 in Resilient Infrastructure Conference Handbook. Rotorua 8–9 August 2005.
Bruneau, M, S Chang, R Eguchi, G Lee, T O’Rourke, A Reinhorn, M Shinozuka, K Tierney, W Wallace and D
von Winterfelt (2003) A framework to quantitatively assess and enhance the seismic resilience of
communities. EERI Spectra Journal 19, no.4: 733–752.
Christchurch Engineering Lifelines Group (1997) Risks and realities. A multidisciplinary approach to the
vulnerability of lifelines to natural hazards. Christchurch: University of Canterbury.
Comfort, L (1999) Shared risk: complex systems in seismic response. New York: Pergamon.
Measuring the resilience of transport infrastructure
54
Commonwealth of Australia (2011) Organisational resilience. Position paper for critical infrastructure.
Accessed 24 November 2013.
www.emergency.qld.gov.au/publications/pdf/Organisational_Resilience.pdf
Croope, S (2010) Managing critical civil infrastructure systems: improving resilience to disasters. PhD
dissertation, University of Delaware.
Dantas, A and S Giovinazzi (2010) Benchmarking the readiness of road controlling authorities to meet
their obligations under the Civil Defence and Emergency Management (CDEM) Act 2002. NZ Transport
Agency research report 409. 90pp.
Deloitte (2013) Building our nation’s resilience to natural disasters. Report prepared by Deloitte Access
Economics for the Australian Business Roundtable for Disaster Resilience and Safer Communities.
Engle, NL (2011) Adaptive capacity and its assessment. Global Environmental Change 21: 647–656.
Folke C, S Carpenter, T Elmqvist, L Gunderson, CS Holling, B Walker, J Bengtsson, F Berkes, J Colding, K
Danell, M Falkenmark, L Gordon, R Kasperson, N Kautsky, A Kinzig, S Levin, K-G Mäler, F Moberg, L
Ohlsson, P Olsson, E Ostrom, W Reid, J Rockström, H Savenije and U Svedin (2002) Resilience and
sustainable fevelopment: building adaptive capacity in a world of transformations. ICSU Series on
Science for Sustainable Development, no.3.
Foster, HD (1997) The Ozymandias principles: thirty-one strategies for surviving change. Victoria, BC: UBC
Press.
Gallopin, G (2007) Linkages between vulnerability, resilience and adaptive capacity. Formal Approach to
Vulnerability Workshop, Potsdam Institute for Climate Impact Research. Potsdam, 13–14 September
2007.
Gardiner, L, D Firestone, G Waibl, N Mistal, K Van Reenan, D Hynes, J Smart, J Byfield, S Oldfield, S Allan, B
Kouvelis, A Tait and A Clark (2008). Climate change effects on the land transport network. Volume one:
literature review and gap analysis. NZ Transport Agency research report 378. 226 pp.
Godschalk, DR (2002) Urban hazard mitigation: creating resilient cities. Urban Hazards Forum, John Jay
College, City University of New York, January 2002.
Godschalk, DR, T Beatley, P Berke, DJ Brower and EJ Kaiser (1999) Natural hazard mitigation: recasting
disaster policy and planning. Washington, DC: Island Press.
Gordon, M and S Matheson (2008) Engineering lifelines and transport – should New Zealand be doing it
better? Part one. Phase 1: Situation scan. Phase 2: New Zealand risk exposure. NZ Transport Agency
research report 355A. 94pp.
Grubinger, V (2012) Resilience and sustainability in the food system. Accessed February 2013.http://learn.uvm.edu/foodsystemsblog/2012/10/22/resilience-and-sustainability-in-the-food-system/
Hamad, K and S Kikuchi (2002) Developing a measure of traffic congestion: fuzzy inference approach.
Transportation research record no.1802: 77–85.
Heaslip, K, W Louisell and J Collura (2009) A methodology to evaluate transportation resiliency for regional
network. 88th Transportation Research Board Annual Meeting. Washington DC.
Heaslip, K, W Louisell, J Collura and N Urena Serulle (2010) An evaluation of network transportation
siliency for disasters and other events. 89th Annual Meeting of the Transportation Research Board.
Washington DC.
10 References
55
Hillson, D (2013) Accessed May 2013.http://programme-recruitment.com/dr-david-hillson-s-article-
archive.../opportunities-are-the-same-as-threats..
Hollnagel, E (2011) Understanding accidents, or how (not) to learn from the past. Accessed May 2013.
www.functionalresonance.com/FRAM-1_understanding_accidents.pdf
Ladbrook, W (2012) Infrastructure resilience. What does it mean for my agency/organisation? Version 1.0.
Lee, A, J Vargo and E Seville (2013) Developing a tool to measure and compare organisations’ resilience.
Natural Hazards Review 14, no.1: 29–41.
Levina, E and D Tirpak (2006) Adaptation to climate change: key terms. Report for the Organisation for
Economic Co-operation and Development and International Energy Agency.
McRoberts, N (2010) Sustainability and resilience demystified. Accessed February 2013,
www.knowledgescotland.org/briefings.php?id=116
Madni, AM and S Jackson (2009) Towards a conceptual framework for resilience engineering. Systems
Journal, IEEE 3, no.2: 181–191.
Maguire, B and S Cartwright (2008) Assessing a community’s capacity to manage change: a resilience
approach to social assessment. Report for the Australian Government Bureau of Rural Sciences.
Malone, EL (2009) Vulnerability and resilience in the face of climate change: current research and needs
for population information. Report prepared by Batelle Memorial Institute. Washington: DC: Population
Action International.
Manyena, S, G O’Brien, P O’Keefe and J Rose (2011) Disaster resilience: a bounce back or bounce forward
ability? Local Environment 16, no.5: 417–424.
Mayunga, J (2007) Understanding and applying the concept of community disaster resilience: a capital-
based approach. Accessed 25 November 2013. www.ehs.unu.edu/file/get/3761
Mello, L (2005) Fat-tailed distributions in catastrophe prediction. CoRR abs/cs/0512022. Accessed 25
November 2013.http://arxiv.org/ftp/cs/papers/0512/0512022.pdf
Mileti, DS (1999) Disaster by design: a reassessment of natural hazards in the United States. Washington
DC: Joseph Henry Press.
Mostashari, A, M Omer and R Nilchiani (2009) Assessing resilience in a regional road based transportation
network. Hoboken, NJ: Stevens Institute of Technology.
Murray-Tuite, P (2006) A comparison of transportation network resilience under simulated system
optimum and user equilibrium conditions. In Proceedings of the 2006 Winter Simulation Conference,
Monterey, CA.
Ministry for the Environment (2008) Climate change effects and impacts assessment. A guidance manual
for local government in New Zealand. 2nd ed. Wellington: Ministry for the Environment.
Ministry of Civil Defence & Emergency Management (CDEM) (2005) Recovery management. Director’s
guidelines for CDEM Groups [DGL 4/05].
National Infrastructure Advisory Council (NIAC) (2010) A framework for establishing critical infrastructure
resilience goals. Final report and recommendations by the council. Washington DC.
National Infrastructure Unit (NIU) (2011) National infrastructure plan 2011. Wellington: National
Infrastructure Unit, The Treasury.
Measuring the resilience of transport infrastructure
56
National Infrastructure Unit (NIU) (2012) National infrastructure plan – resilience. Stakeholder memo from
Roger Fairclough (NIU). Accessed 25 November 2013.
www.infrastructure.govt.nz/plan/2011implementation/nip-resil-28jun12.pdf
New Zealand Asset Management Support (NAMS) (2011) International infrastructure management manual.
Wellington: NAMS Group.
New Zealand Government (2012) Infrastructure 2012. National state of infrastructure report. Wellington:
National Infrastructure Advisory Board and National Infrastructure Unit, The Treasury.
O’Rourke, TD (2007) Critical infrastructure, interdependencies and resilience. The Bridge 37, no.1.
Park, J, TP Seager, PSC Rao, M Convertino and I Linkov (2013) Integrating risk and resilience approaches to
catastrophe management in engineering system. Risk Analysis 33, no.3: 356–367.
PwC Ltd and GHD Ltd (2012) Implementing the national infrastructure plan in the water industry – a pilot
study. Accessed June 2013. www.waternz.org.nz/Category?Action=View&Category_id=98
Resilient Organisations (2012) What is organisational resilience? Accessed 15 February 2013.
www.resorgs.org.nz/Content/what-is-organisational-resilience.html
Saunders, C, W Kaye-Blake, R Campbell, P Dalziel and K Kolandi (2010) Capital based sustainability
indicators as a possible way for measuring agricultural sustainability, ARGOS research report 10/02.
Seville, E (2009) Resilience: great concept but what does it mean for organisations? Tephra 22: 9–15.
Community resilience special issue.
Seville, E and J Metcalfe (2005) Developing a hazard risk assessment framework for the New Zealand state
highway network. Land Transport NZ research report 276. 80pp.
Seville, E, D Brunsdon, A Dantas, J Le Masurier, S Wilkinson and J Vargo (2006) Building organisational
resilience: a summary of key research findings. Resilient Organisations research report 2006/04.
Snowdon, D (2006) Safe-fail or fail-safe. Accessed June 2013.http://cognitive-
edge.com/blog/entry/4501/safe-fail-or-fail-safe/
Snowdon, D (2011) Risk and resilience. Accessed June 2013. www.youtube.com/watch?v=2Hhu0ihG3kY
Solomon, S, D Qin, M Manning, Z Chen, M Marquis, KB Averyt, M Tignor and HL Miller (Eds) (2007) Climate
change 2007: the physical science basis. Contribution of Working Group I to the Fourth Assessment
Report of the Intergovernmental Panel on Climate Change. Cambridge, UK and New York, USA:
Cambridge University Press: 996pp.
Stockholm Resilience Centre (2007) What is resilience? Accessed February 2013.
www.stockholmresilience.org/21/research/what-is-resilience.html
Taleb, N (2010) The black swan: the impact of the highly improbable. 2nd ed. New York: Random House.
Treasury (2011a) Better capital planning and decision making. Wellington: The Treasury.
Treasury (2011b) Working towards higher living standards for New Zealanders. Wellington: The Treasury.
Treasury (2012) Better business cases. Wellington: The Treasury.
United Nations Disaster Relief Co-ordinator (UNDRO) (1980) Natural disasters and vulnerability analysis.
Report of Experts Group, meeting of 9–12 July 1979. Geneva: UNDRO.
United Nations International Strategy for Disaster Reduction (UNISDR) (2004) Living With risk. A global
review of disaster reduction initiatives. Geneva: UNISDR.
10 References
57
United States Department of Homeland Security (USDHS) (2009a) Concept development: an operational
framework for resilience. Prepared for Department of Homeland Security Science and Technology
Directorate.
United States Department of Homeland Security (USDHS) (2009b) National infrastructure protection plan.
Partnering to enhance protection and resiliency.
Urena Serulle (2010) Transportation network resiliency: a fuzzy systems approach. Accessed 29 November
2013.http://digitalcommons.usu.edu/etd/769/
URS (2005) Critical land transport infrastructure risk management review. Report prepared for Ministry of
Transport, Wellington.
Victoria Transport Policy Institute (VTPI) (2010) Evaluating transport resilience. Evaluating the
transportation system’s ability to accommodate diverse, variable and unexpected demands with
minimal risk. Accessed February 2013. www.vtpi.org/tdm/tdm88.htm
Zolli, A (2012) Goodbye sustainability, hello resilience. Accessed September 2013.http://andrewzolli.com/from-sustainability-to-resilience/
Measuring the resilience of transport infrastructure
58
Appendix A: NZ Transport Agency risk tool
Table A.1 Consequence rating
The outcome to the organisation from the risk event if it is not mitigated/treated more than it is currently
Minimal Minor Moderate Major Substantial
Category Sub-category 1 10 40 70 100
Financial
(operational/
capital funding)
–
Minor variance able to be
absorbed within budget
$100,000 to 25% capacity of failed mode(s)
N/A - Provide no score
N/A
Back up
inventories
and
equipment
Region Availability of back up
equipment and replacement
inventories available to
respond to an event
Existence of plan/requirements for back
up equipment relevant to different
hazards and critical assets.
Availability/readiness of back up
equipment for deployment
4 – Requirements are well specified for different assets.
Equipment is available and ready
3 – Requirements are well specified, however, not enacted
2 – Ad hoc approach
1 – No plan/requirements
2.0
Procedural Diversion and
communicatio
n plans
Region Diversion plans to alternate
routes
Existence of robust, tested plans to
establish diversions to alternate routes
when failure of critical link occurs
4 – Plans are well specified for different assets. Systems are
available, tested and ready
3 – Plans are well specified, however, not enacted
2 – Ad hoc approach
1 – No plan/requirements
2.0 2.0 33.33% 66.66
Measuring the resilience of transport infrastructure
64
REDUNDANCY continued Weighted redundancy score 2.0
Category 1 Category 2 Filter: asset or
regional
(network)
assessment
Item# Item measured Measurement Measurement scale Individual
score
Category
average
Weighting
(%)
Weighted
score
Note/justification
Inter-
dependencies
Supplier
utility
redundancy
Region Awareness of redundancy
issues (vulnerabilities) in
supplier utilities. Do
suppliers have sufficient
system redundancy,
resources, backup,
materials, fuel etc to provide
sufficient redundancy
Supplier staff and Transport Agency staff
aware of redundancy issues within
suppliers utilities (power, telecom, other)
4 – Good awareness and have been followed up
3 – Some awareness
2 – Minor awareness
1 – No awareness 2.0
2.0 33.33% 66.66
Supplier
utility
procedures
Region Suppliers have implemented
procedures to
measure/improve
redundancy
Evidence that suppliers have
implemented procedures and
improvements and that these are
effective
4 – Suppliers have developed and implemented procedures
and there is strong dialogue
3 – Initial dialogue and plans are being prepared
2 – Initial dialogue
1 – No action or evidence
2.0
SAFE-TO-FAIL Weighted safe-to-fail score 2.0
Category 1 Category 2 Item# Item measured Measurement Measurement scale Individual
score
Category
average
Weighting
(%)
Weighted
score
Note/justification
Structural
Design Region Have safe-to-fail design
approaches been considered
in conjunction with
robustness and redundancy
design approaches (where
considered relevant) for
existing assets?
Evidence that safe-to-fail is considered
across critical asset/route designs in the
region and when planning for asset
renewal and upgrades to improve
resilience
4 – Design documentation shows consideration or
incorporation of safe-to-fail approaches for >80% of critical
assets where relevant.
3 – Design documentation shows consideration or
incorporation of safe-to-fail approaches for >50%, 50%, 75% reached
2 – > 40-75% reached
1 –
The New Zealand Transport Agency ('the Transport Agency') has a key interest in ensuring that transport infrastructure assets and services function continually and safely. This interest has led to a specific focus on the concept of resilience and how this can be defined, measured and improved across the transport system.
Measuring the resilience of transport
infrastructure
February 2014
JF Hughes and K Healy
AECOM New Zealand Ltd
NZ Transport Agency research report 546
Contracted research organisation – AECOM New Zealand Ltd
ISBN 978-0-478-41915-3 (electronic)
ISSN 1173-3764 (electronic)
NZ Transport Agency
Private Bag 6995, Wellington 6141, New Zealand
Telephone 64 4 894 5400; facsimile 64 4 894 6100
[email protected]
www.nzta.govt.nz
Hughes, JF and K Healy (2014) Measuring the resilience of transport infrastructure. NZ Transport Agency
research report 546. 82pp.
AECOM New Zealand Ltd was contracted by the NZ Transport Agency in 2012 to carry out this research.
This publication is copyright © NZ Transport Agency 2014. Material in it may be reproduced for personal
or in-house use without formal permission or charge, provided suitable acknowledgement is made to this
publication and the NZ Transport Agency as the source. Requests and enquiries about the reproduction of
material in this publication for any other purpose should be made to the Manager National Programmes,
Investment Team, NZ Transport Agency, at [email protected]
Keywords: criticality, failure, hazards, infrastructure, resilience, risk, transport, vulnerability
An important note for the reader
The NZ Transport Agency is a Crown entity established under the Land Transport Management Act 2003.
The objective of the Agency is to undertake its functions in a way that contributes to an efficient, effective
and safe land transport system in the public interest. Each year, the NZ Transport Agency funds innovative
and relevant research that contributes to this objective.
The views expressed in research reports are the outcomes of the independent research, and should not be
regarded as being the opinion or responsibility of the NZ Transport Agency. The material contained in the
reports should not be construed in any way as policy adopted by the NZ Transport Agency or indeed any
agency of the NZ Government. The reports may, however, be used by NZ Government agencies as a
reference in the development of policy.
While research reports are believed to be correct at the time of their preparation, the NZ Transport Agency
and agents involved in their preparation and publication do not accept any liability for use of the research.
People using the research, whether directly or indirectly, should apply and rely on their own skill and
judgement. They should not rely on the contents of the research reports in isolation from other sources of
advice and information. If necessary, they should seek appropriate legal or other expert advice.
Acknowledgements
The authors would like to acknowledge the following people for their assistance with this project:
Michael Nolan, Mark Gordon, Roger Fairclough, Dr Erica Seville, Craig Omundsen, Brian Sharman, Dr Cliff
Naude, Dr Ron McDowall, Gavin Armstrong, Brandon Mainwaring, Sandy Fong, Ian Duncan.
Abbreviations and acronyms
CDEM Ministry of Civil Defence & Emergency Management (New Zealand)
IPCC Intergovernmental Panel on Climate Change
NIAC National Infrastructure Advisory Council (US)
NIP National Infrastructure Plan
NIU National Infrastructure Unit
TMP traffic management plan
TOSE technical, organisational, societal, economic
Transport Agency New Zealand Transport Agency
UNDRO United Nations Disaster Risk Organisation
UNISDR United Nations International Strategy for Disaster Reduction
USDHS United States Department of Homeland Security
VTPI Victoria Transport Policy Institute
5
Contents
Executive summary ................................................................................................................................................................. 7
Abstract ....................................................................................................................................................................................... 10
1 Introduction ................................................................................................................................................................ 11
1.1 Background ................................................................................................................... 11
1.2 Purpose ......................................................................................................................... 11
1.3 Methodology ................................................................................................................. 11
1.4 Report structure and target audience ......................................................................... 12
2 Context of this study ............................................................................................................................................ 13
2.1 National Infrastructure Plan 2011 ............................................................................... 13
2.2 Responsibilities and perspectives on resilience ......................................................... 14
2.3 Challenges in planning for resilience .......................................................................... 15
2.4 Summary ....................................................................................................................... 16
2.4.1 Main points ..................................................................................................... 16
2.4.2 Relevance to framework development ........................................................... 17
3 The importance of resilient infrastructure ............................................................................................. 18
3.1 Why is resilience important? ........................................................................................ 18
3.2 Complex interdependencies ........................................................................................ 18
3.3 Summary ....................................................................................................................... 20
3.3.1 Main points ..................................................................................................... 20
3.3.2 Relevance to framework developments ......................................................... 20
4 What is resilience? .................................................................................................................................................. 21
4.1 Defining resilience ....................................................................................................... 21
4.1.1 Resilience, vulnerability and sustainability .................................................... 23
4.2 Hazards, risk and resilience ........................................................................................ 23
4.3 Dimensions and principles of resilience ..................................................................... 25
4.3.1 Dimensions of resilience ................................................................................ 26
4.3.2 Principles of resilience .................................................................................... 27
4.4 Summary ....................................................................................................................... 31
4.4.1 Main points ..................................................................................................... 31
4.4.2 Relevance to framework development ........................................................... 31
5 How can we measure resilience? .................................................................................................................. 32
5.1 Resilience to what? ....................................................................................................... 32
5.1.1 An all-hazards vs specific hazard approach .................................................. 33
5.2 Conceptual/qualitative frameworks ............................................................................ 33
5.3 Quantitative approaches .............................................................................................. 35
5.4 Recommended measurement approach ...................................................................... 35
5.5 Summary ....................................................................................................................... 36
5.5.1 Main points ..................................................................................................... 36
5.5.2 Relevance to framework development ........................................................... 37
6 A proposed measurement framework for transport system resilience ................................ 38
6.1 Resilience assessment context .................................................................................... 40
6.2 Resilience measures ..................................................................................................... 40
6
6.2.1 Application of weightings ............................................................................... 44
6.3 Summary ....................................................................................................................... 44
6.3.1 Main points ...................................................................................................... 44
7 Implementation of the framework ............................................................................................................... 45
7.1 Summary ....................................................................................................................... 47
8 Example assessments .......................................................................................................................................... 48
8.1 Regional all-hazard assessment ................................................................................... 48
8.2 Asset, hazard-specific assessment .............................................................................. 49
9 Conclusions and recommendations ............................................................................................................ 51
9.1 Conclusions................................................................................................................... 51
9.2 Recommendations ........................................................................................................ 51
10 References ................................................................................................................................................................... 53
Appendix A: NZ Transport Agency risk tool ........................................................................................................ 58
Appendix B: Resilience assessment example ...................................................................................................... 60
Appendix C: Resilience, vulnerability and sustainability ............................................................................. 74
Appendix D: Criticality ....................................................................................................................................................... 76
Appendix E: Hazards, rare events and failure modes .................................................................................... 78
Appendix F: User guidance ............................................................................................................................................. 82
Executive summary
The New Zealand Transport Agency (‘the Transport Agency’) has a key interest in ensuring that transport
infrastructure assets and services function continually and safely. This interest has led to a specific focus
on the concept of resilience and how this can be defined, measured and improved across the transport
system.
As a result, from late 2012 to mid-2013, the Transport Agency engaged AECOM to develop a framework to
measure the resilience of the New Zealand transport system.
The project involved initial research and scoping to determine the project boundaries and definitions, and
following this, the development of a practical framework and assessment tool.
The framework is applicable to the broad land transport system (road and rail) and allows consideration of
various scales (asset/network/region).
Critical infrastructure and hazards
Infrastructure is recognised as a critical element to healthy economies and stable communities. It enables
commerce, movement of people, goods and information, and facilitates society’s daily activities.
In a transport context, societies rely on transportation networks for their daily economic and social
wellbeing. The ability of the transport system to function during adverse conditions and quickly recover to
acceptable levels of service after an event is fundamental to the wellbeing of communities.
Furthermore, the risks to critical infrastructure from hazards are, according to research, increasing
globally. These hazards can include natural, technological, social and political hazards, each of which can
occur with a varying degree of predictability.
The hazard scenarios are further amplified due to complex interdependencies between modern
infrastructure networks, and the existence of many different failure modes – all of which can affect the
functioning of infrastructure.
What is resilience?
Resilience is considered the ultimate objective in the context of hazard mitigation. There is a variety of
definitions which have evolved as different disciplines have applied resilience thinking to their work and
adapted the definitions to meet their focus.
A definition which is both applicable to the New Zealand transport context and is consistent with
international literature is that provided within the Treasury’s National infrastructure plan (NIP):
The concept of resilience is wider than natural disasters and covers the capacity of public,
private and civic sectors to withstand disruption, absorb disturbance, act effectively in a
crisis, adapt to changing conditions, including climate change, and grow over time.
This definition acknowledges that the service the infrastructure delivers will be disrupted, due to damage
to the infrastructure; however, the service is able to reduce the possibility of failure, adapt and recover
from a disruptive event and/or gradual external changes over time. It also implies transformation, so not
only is the infrastructure service able to survive or recover but it can adapt to a changing environment in
which it operates. Finally, the definition is broad enough to encompass more recent approaches that allow
for ‘unknown’ as well as ‘known’ hazards.
Measuring the resilience of transport infrastructure
8
To further understand resilience, researchers have identified a number of dimensions, principles and
measures of resilience. By defining and categorising these dimensions and principles, the broad
framework elements can be built, from which meaningful and practical measures can then be developed.
The literature review identified two dimensions of resilience – technical and organisational – as being
representative of the range of broad considerations for assessing resilience.
Similarly, in terms of resilience principles, the following were chosen, grouped under the two dimensions
above. These principles form the basis for the framework development:
• technical principles: robustness, redundancy, safe-to-fail
• organisational principles: change readiness, leadership and culture, networks.
A framework for measuring transport system resilience
A broadly qualitative framework for measuring resilience was created, based on the dimensions and
principles described above. Specific, detailed measurement categories were developed under each of the
principles.
The framework involves an initial determination of the context of the resilience assessment, followed by a
detailed assessment of resilience measures, which combine to generate a resilience score ranging from 4
(very high resilience) to 1 (low resilience). These measures can then be aggregated and weighted as required.
4 Very high resilience – meets all requirements
3 High resilience – acceptable performance in relation to a measure(s), some improvements could be made
2 Moderate resilience – less than desirable performance and specific improvements should be prioritised
1 Low resilience – poor performance and improvements required.
A number of cross-cutting themes were developed to influence the context and approach of the resilience
assessment. These are summarised and discussed in the table below.
Table 1 Cross-cutting themes
Cross-cutting theme Discussion
All hazards/specific
hazard approach
The assessment can be undertaken in one of two ways:
1 An all-hazards assessment – based on an event due to any (unspecified)
hazard/failure, which could be either known or unknown.
2 A hazard-specific assessment could be undertaken. This would involve identifying the
relevant known hazard types and assessing the resilience to each.
Scale of assessment The framework will allow assessment at various scales: regional, network or asset.
Measures have been developed for each and the user can filter the questions accordingly.
Regional assessments could be aggregated to a national indicator if desired.
Shock event or stress
event
The framework will be able to evaluate both short-term shock events (eg earthquakes and
tsunamis) and longer-term stress events (eg climate change related).
In summary, the approach to undertaking the resilience assessment is as follows:
1 Determine the context of the assessment:
a all-hazards or specific hazards (including shock or stress event, rare events etc)
b scale: asset/network/regional
c shock or stress event
Executive summary
9
2 Undertake the assessment, using the relevant questions and assigning scores
3 Apply weightings to categories as required
4 Generate resilience scores for categories, principles and dimensions and a total score.
As a stand-alone assessment, the resilience measurement framework could be applied to generate a
relative score for comparing resilience across assets/networks or regions. However, to provide additional
rigour, other steps could be applied during implementation.
Implementation of the framework
To implement the measurement framework in a systematic manner, additional steps could be
incorporated to determine priorities for intervention. These steps include determining:
1 Which infrastructure should be assessed for resilience?
2 What level of resilience is appropriate for a given asset/network?
In order to answer these questions, an understanding is required of both the criticality of a given asset,
and the risk of a particular hazard occurring. Note, this corresponds directly to whether a general ‘all-
hazards’ or ‘hazard-specific’ assessment has been chosen.
The all-hazards approach would involve an assessment of criticality to determine which assets should be
focused on for the resilience assessment. The criticality assessment would identify which assets merit a
certain ‘desired’ level of resilience, and then following a resilience assessment for these assets, related
improvements or interventions could be targeted.
If further detail was required, a more detailed hazard-specific assessment could be undertaken. This would
provide information on the relevant hazards and the likelihood of their occurring. In this case, the output
of the risk assessment would determine the ‘desired’ level of resilience.
The Transport Agency currently has a risk assessment tool based on AS/NZS 31000, as well as a state
highway classification system that could be utilised to determine criticality of assets. The rail system and
local authorities may have similar methods for determining criticality.
In terms of application across different scales, the following approaches could be implemented. Any
approach could be used at any scale; however, the following are considered the most appropriate.
• Asset scale: Either an ‘all-hazards’ approach using criticality as a first step, or a hazard-specific
approach using risk assessment. Resilience assessment would be compared against ‘desired’ level of
resilience for the asset to determine the need for intervention.
• Network/route scale: Either an ‘all-hazards’ approach for all critical assets within the network using
criticality as a first step, or a hazard-specific approach using risk assessment. Resilience assessment
would be compared against ‘desired’ level of resilience for the network to determine the need for
intervention.
• Regional scale: Stand-alone resilience assessment either via an ‘all-hazards’ approach or a hazard-
specific approach. This would enable regions to be compared, and actions and interventions to be
prioritised across regions.
Conclusions and recommendations
The framework developed through this study is applicable to the broad land transport system (road and
rail) and allows an assessment at various scales (asset/network/region). It also gives effect to the guiding
principle of resilience within the NIP.
Measuring the resilience of transport infrastructure
10
Due to project constraints, detailed real-scenario testing of the framework was not undertaken. Specific
operator knowledge of assets and the relevant organisations would be required to undertake a meaningful
assessment. As such, this and other recommendations for future work are made below.
• Undertake a real-scenario testing of the framework with key operational staff.
• Undertake further work to improve understanding of critical infrastructure and factors which may
determine criticality – from both an economic and societal point of view.
• Undertake further economic and engineering research to better understand and quantify a suitable
level of investment in technical (structural) resilience. This is generally where significant capital
expenditure is required and is difficult to justify when funding is limited
• Improve understanding of linkages between resilience and sustainability. To date, conversations
around infrastructure resilience have occurred largely in isolation of those which occur around
sustainability.
Abstract
Internationally there is a growing call to improve the resilience of our critical infrastructure. This is in
response to a realisation that the services we take for granted may be robust in the face of predictable
hazards/failures, but are in fact extremely fragile in the face of unanticipated shocks.
In the context of transport infrastructure, operators strive to ensure that transport assets and services
function continually and safely in the face of a range of existing and emerging hazards. This has led to a
specific focus on the concept of resilience and how this can be defined, measured and improved across
the transport system.
The theory of resilience was researched and a measurement framework has been proposed that broadly
covers both technical and organisational dimensions of resilience and breaks these down into specific
principles and measures which can be utilised to qualitatively assess resilience.
The measurement of resilience was approached from a view that a risk management approach alone is not
sufficient and needs to be complemented by an awareness that resilience requires both consideration of
events that fall outside of the realms of predictability and, importantly, that failure is inevitable.
1 Introduction
11
1 Introduction
1.1 Background
The New Zealand Transport Agency (the ‘Transport Agency’) is primarily responsible for managing
New Zealand’s state highway network. It is actively involved in strategy and planning at a national and
regional level, with a strong focus on integration with both rail and port services.
Additionally, the Transport Agency has a key interest in ensuring that transport infrastructure assets and
services function continually and safely. This interest has led to a specific focus on the concept of
resilience and how it can be defined, measured and improved across the transport system. This was
highlighted by the National infrastructure plan 2011 (National Infrastructure Unit 2011), which identifies
‘resilience’ as one of six guiding principles to ‘provide a platform for infrastructure development’ and
‘signal how the country should move forward and make better decisions in the future’.
1.2 Purpose
The purpose of this research was to develop a framework and assessment tool to measure the resilience
of transport infrastructure, which is practical and feasible to implement, and which:
• will be applicable to the wider land transport system (road and rail), and will allow consideration of
various scales (asset/network/region)
• can link to broader criticality and risk management approaches allowing prioritisation of
improvements and interventions.
1.3 Methodology
A three-staged approach was followed, as illustrated in figure 1.1:
1 Initial research and scoping – including literature review and definition of the term ‘resilience’
2 Development of a framework and assessment tool, which is practical and feasible to implement
3 Implementation example.
The project team consisted of New Zealand based and international AECOM staff. The review was
undertaken both by key Transport Agency staff and steering group members consisting of staff from the
Treasury and Ministry of Transport. Finally, two peer reviewers were engaged to provide input following
each stage of the project.
Measuring the resilience of transport infrastructure
12
Figure 1.1 Outline of project methodology
1.4 Report structure and target audience
This research report has been developed in-line with the three-stage methodology and designed to guide
agency management and operators in their engagement with transport resilience in New Zealand.
Chapters 1 to 5 relate to work undertaken during stage one, and detail the objectives and background of
the study, define key terms, context and key considerations for measuring resilience. More specifically:
• Chapters 1 and 2 provide introduction and context.
• Chapter 3 discusses the importance of resilience and different stakeholder perspectives.
• Chapter 4 defines resilience, and related dimensions and principles
• Chapter 5 discusses how resilience can be measured and also what hazards are of relevance
• Chapters 6 and 7 bring together the preceding work and cover the development of the proposed
measurement framework and recommend specific measurements for resilience, as well as providing
suggestions around implementation and linking to existing criticality and risk frameworks
• Chapter 8 gives some examples of implementation.
• Chapter 9 contains the conclusion and recommendations for future work.
2 Context of this study
13
2 Context of this study
This section covers the context in which the resilience framework and resilience measures must operate.
The New Zealand government has released a number of publications which establish guidance principles,
context and direction for the provision and management of infrastructure in New Zealand.
The first of these is Working towards higher living standards for New Zealanders (Treasury 2011b). This
publication focuses on how improved economic performance can lead to enhanced living standards and
outlines a series of dimensions which contribute to achieving this. These dimensions include ‘reducing
risk’, and ‘improving New Zealand’s ability to withstand unexpected shocks’. In the context of physical or
social infrastructure, this could be viewed as building resilience.
Additionally, Treasury has published Better business cases (Treasury 2012) and the Better capital planning
and decision making (Treasury 2011a).
The purpose of these two complementary publications is to deliver better value for money through public
investment and ultimately better outcomes and service delivery to the public. The key messages focus on
robust planning, analysis, decision-making and implementation in order to ensure project success.
Treasury (2011a) covers the fundamental principles of good asset management and planning, which, in
turn, incorporate an assessment of critical assets and business risk when developing business cases.
Finally, Treasury has released the National infrastructure plan (NIP) (NIU 2011). This document establishes
resilience as a key area of focus and is discussed further below.
2.1 National Infrastructure Plan 2011
The NIP covers the transport, telecommunications, energy, water and social infrastructure sectors, and
sets out a vision that ‘by 2030, New Zealand’s infrastructure is resilient and coordinated and contributes
to economic growth and increased quality of life’.
The NIP establishes six guiding principles as a platform for infrastructure development: investment
analysis, resilience, funding mechanisms, accountability and performance, regulation and coordination.
For each of these principles a high-level assessment was undertaken for each sector (figure 2.1), with
resilience within the transport sector assessed as ‘occurs effectively’. It is understood that this high-level
assessment was not the result of a robust or evidence-based assessment (R Fairclough, pers comm).
In order to provide clarity and robustness to this high-level assessment, the NIP acknowledges that
significant work is required to develop indicators for the assessment areas shown in figure 2.1, both
within and across sectors. Agencies and industry bodies are therefore being encouraged to develop
indicators which are relevant, transparent, replicable and can be standardised.
In this context, the Transport Agency commissioned this research project to develop a framework to
measure resilience for the land transport system.
Measuring the resilience of transport infrastructure
14
Figure 2.1 NIP high-level assessment of current infrastructure situation
Source: Treasury (2011)
Subsequent to the publication of the NIP, the NIU has further developed its thinking around resilience and
how this applies to infrastructure. A series of eight resilience attributes have been developed which aim to
achieve a common understanding of resilience as it applies to national infrastructure. These are: service
delivery, adaptation, community preparedness, responsibility (voluntary and regulatory),
interdependencies (consideration of linkages), financial strength, continuous (vigilance and assurance) and
organisational performance (leadership and culture).
These attributes provide context to the measurement framework presented in this report and are
discussed further in section 4.3. Effort has been made in developing the framework to be clear on a) how
the framework elements ‘map’ to the NIU attributes, and b) how a specific assessment(s) could provide a
national-level picture of resilience performance.
2.2 Responsibilities and perspectives on resilience
In New Zealand, those utilities responsible for delivering and maintaining critical infrastructure have been
denoted ‘lifeline utilities’. These have been defined as part of the Civil Defence and Emergency Management
Act 2002. This act sets out which sectors are considered critical lifeline infrastructure (utilities) and includes:
transport, water, wastewater, stormwater, energy and telecommunications services. All lifeline organisations
have a direct interest in understanding and developing resilience to hazards across all the utility organisations
both because of their operational interdependence, and in their desire to function to their fullest possible level
of service. The framework set out in this report will allow consideration of these interdependencies and the
framework principles will be broadly applicable across the range of sectors/utilities.
In addition to the lifeline utilities, there are a range of other stakeholders – each of whom may have a
slightly different perspective on ‘resilience’. These perspectives influence priorities and where investment
is targeted to improve resilience. Table 2.1 below summarises these perspectives.
Table 2.1 Stakeholders and perspectives on resilience
Stakeholder Perspective
User:
The direct or indirect customer/user of the
infrastructure, which may be for business or
personal purposes. For example:
• direct – freight companies, or commuters
using the road network
• indirect – those who receive goods and key
supplies, such as supermarkets.
Users expect the level of service they are accustomed to, to be
restored following an event. They may accept a lower level of
service for a period of time that is proportional to the severity of
an event; however, they may be less accepting of a lower level of
service for extended periods.
The owner and operator of the infrastructure need to understand
the length of time the user will tolerate decreased levels of
service.
2 Context of this study
15
Stakeholder Perspective
Operator and maintainer:
Government agency, local government, utility
company or private contracted organisation.
Operators need to deliver resilience which does not adversely
raise the cost of maintenance and operational expenditure.
They have a key interest in interdependencies and potential
cascade failure.
Government/owner:
Both central and local government, related
agencies and utilities.
Government and related agencies deliver resilience for the
community, and therefore need to consider broader social as
well as economic objectives, with a key interest in
interdependencies.
Infrastructure reliability has political significance through the
way infrastructure disruptions are perceived by constituents.
Robust business cases are required for investment in resilience.
Funding organisation:
Private financier of capital and/or operations and
maintenance.
Funding organisations need to deliver resilience to protect the
investment in existing assets, with a focus on value for money
and a robust business case.
Insurer: The insurer has a vested interest in reducing the risk profile as a
result of resilience improvements.
From a national transport perspective, the Transport Agency is considered to be the owner’s
representative, operator and funder, ultimately interested in the best resilience outcome for New Zealand
as a whole. This report and the development of a measurement framework for resilience can be used by
the transport sector and will be applicable across a range of scales from regional and national down to the
asset level. Nonetheless, it is important that the perspectives of all stakeholders (especially users) are
considered when determining criticality of elements of the transport network and the corresponding
required levels of resilience (refer chapter 7).
2.3 Challenges in planning for resilience
Resource constraints and the requirement for robust business cases (refer above) put pressure on
organisations to justify all expenditure, and when this expense involves mitigating the risk of future and
uncertain hazard events, consensus among decision makers and stakeholders can be difficult to achieve.
As such, a method to assess resilience of infrastructure and prioritise improvements is considered
important and timely.
Ladbrook (2012) emphasises that building structural resilience requires deliberate choices early in the
development of a project. Opportunities for resilience can be lost if not planned and designed for prior to
implementation, as illustrated in figure 2.2. Decision making to build resilience requires a broad approach
that considers long-term infrastructure resilience and economic optimisation, rather than the sole, narrow
perspective of short-term ‘return on investment’ views.
Measuring the resilience of transport infrastructure
16
Figure 2.2 Opportunity to build resilience in planning and design
Despite this agreed need to build resilience, there are, however, few (if any) practical methods for the
application of resilience in engineering design. Park et al (2013) highlight a number of challenges that will
need to be overcome in order to design for resilience:
• Engineering challenges need to be seen as conditions to be managed, rather than problems to be
solved.
• Current approaches focus on known, identified hazards and ignore the significance of unidentified
hazards either via assumption or because of cost constraints. This issue is fundamental when
exploring resilience and risk, and one which is discussed further in subsequent sections.
• Current design practices are based on existing codes and are sanctioned by agencies. These codes
ignore the possibility of unidentified or emergent hazards, and lead to incremental evolution of
design, rather than encouraging innovative design.
While it will not establish parameters for engineering design, the framework set out in this report will
address some of these challenges and provide a method for assessing and measuring the resilience of
transport infrastructure, and identifying priority areas for improvement.
2.4 Summary
2.4.1 Main points
The NIP along with Treasury (2012) and Treasury (2011a; 2011b) all establish a context for understanding,
assessing and building resilience in infrastructure. In particular, the NIP provides key attributes for
resilient infrastructure.
There is a wide range of perspectives from which resilience can be assessed – ranging from user, through
to owner, operator, funder and insurer. Each has different perspectives and views on priorities.
There are challenges in planning and designing for resilience and justifying expenditure for mitigating
future, uncertain hazards. A long-term view is required and methods are needed that allow measurement
of resilience.
2 Context of this study
17
2.4.2 Relevance to framework development
The framework needs to:
• give effect to the high-level objectives of the above plans and documents
• relate to the NIP attributes developed
• be applicable across a range of scales (regional – asset), while assuming a national perspective (ie the
best outcome for New Zealand)
• address the challenge of unidentified hazards.
Measuring the resilience of transport infrastructure
18
3 The importance of resilient infrastructure
In this section we cover reasons why resilient infrastructure is important to society. We discuss this in the
context of increasing reliance on critical ‘lifelines’ infrastructure, increasing frequency of hazards and
evolving, complex interdependencies within infrastructure systems. We also explore how different
stakeholders can view resilience from different perspectives.
3.1 Why is resilience important?
Worldwide, infrastructure is recognised as a critical element for healthy economies and stable
communities. It enables commerce, movement of people, goods and information, and facilitates society’s
daily activities. Infrastructure can be considered to include everything from the physical infrastructure of
roads, bridges, airports, rail, water supply, telecommunications and energy services, to the social
infrastructure of health care, education, banking and finance services, emergency services and the justice
system.
Croope (2010) states ‘Critical infrastructure not only responds to the needs of society for the smooth daily
continuation of activities, but also provides the basis on which society exists and relies’.
Godshalk (2002) lists two reasons behind the importance of resilience.
1 Because the vulnerability of technological, natural and social systems cannot be predicted, the ability
to accommodate change without catastrophic failure in times of disaster is critical.
2 People and property fare better in resilient cities when struck by disasters. Fewer buildings collapse,
fewer power outages occur, fewer businesses are put at risk, and fewer deaths and injuries occur.
Societies have an increasing reliance on transportation networks for their daily activities. The ability of the
transport system to function during adverse conditions and quickly recover to acceptable levels of service
after an event is fundamental to the wellbeing of people within society.
The current increased focus on resilience is driven by a raised awareness of hazards due to recent natural
disasters, such as the Christchurch earthquakes, and other natural and technological hazard events globally
(eg the Fukushima nuclear disaster, Hurricane Katrina and the Deep Water Horizon oil spill). Climate change
is also affecting the severity and frequency of events, and creating new hazards in its own right.
Additionally, awareness of unpredictable, ‘rare’ events is increasing, and there is a recognition that
societies need to build resilience to these, in ways that may not have been used in the past.
Finally, complex interdependency in modern infrastructure networks means we need to look further afield
than the principal sector (eg roading network) to other interdependent sectors (eg electricity,
telecommunications) to identify potential failure modes and hazards. This is discussed further below.
3.2 Complex interdependencies
Modern infrastructure networks are increasingly complex and interconnected. These interdependencies
and their many dynamic and multi-dimensional parts necessitate a ‘system of systems approach’ (Croope
2010 and USDHS 2009a) in order to fully understand and assess where vulnerabilities lie and where
resilience can be improved. This is illustrated in figure 3.1.
3 The importance of resilient infrastructure
19
Figure 3.1 Connections and interdependencies across the economy
Source: T O’Rourke
These complex, interconnected systems create benefits and efficiencies at times of normal operation, yet
bring with them vulnerabilities and operational challenges, especially during unexpected circumstances or
when faced with hazards. Extensive analysis of complex engineering systems has revealed that in many
cases ‘failure’ is at best a statistical inevitability, or at worst a part of ‘normal’ operation (Perrow 1984).
Interdependencies can lead to a wide range of potential failure modes and the emergence of previously
unidentified hazards which can cause failure. Hollnagel (2011) categorises the range of failure modes as
simple-linear (or cascade) failure, complex-linear failure (caused through hidden interdependencies or
latent conditions), or complex-nonlinear failure resulting from concurrence of unexpected events. These
are discussed further in section 4.2.
Interdependence can be considered in a number of ways, including physical proximity, operational
interaction and interdependency of stakeholders (owner, funder, operator, insurer). Operational
interdependence can be assessed in terms of both upstream and downstream dependencies. As an
example, upstream for the Transport Agency are those systems/utilities whose failure would impact on
the functioning of its transport network (eg failure of electricity for signals), and downstream being the
systems/utilities which would be affected by failure of the Transport Agency transport network (eg a road
providing access to a power station fails, causing shut down). In the context of measuring resilience for
the transport system, the upstream dependencies are those that should be considered in terms of hazard
identification (with the downstream being important in assessing criticality).
It is considered vital that a detailed consideration and understanding of interdependencies and potential
failure modes is included in any assessment of resilience.
Measuring the resilience of transport infrastructure
20
3.3 Summary
3.3.1 Main points
Resilient infrastructure and specifically resilient transport infrastructure is vital to our modern society and
economy. The increased frequency, intensity and awareness of global hazard events mean that building
resilience is a justified and important goal.
Awareness of unpredictable, ‘rare’ events is increasing and there is a recognition that societies need to
build resilience to these.
Complex interdependencies in modern infrastructure systems necessitate a wide-ranging approach to
assessing hazards and potential failure modes.
3.3.2 Relevance to framework developments
The framework needs to consider the complete range of hazards, including rare events, and complex
failure modes as a result of inter-related, upstream dependencies.
4 What is resilience?
21
4 What is resilience?
This section provides a working definition for ‘resilience’ as well as recommending a series of appropriate
dimensions and principles which will feed into the measurement framework.
4.1 Defining resilience
Resilience is considered the ultimate objective of hazard mitigation, that is, ‘action taken to reduce or
eliminate long-term risk to people and property from hazards and their effects’ (Godschalk 2002).
The term resilience has evolved as different disciplines have applied resilient approaches to their work and
adapted the definitions to meet their focus.
Levina and Tirpak (2006) propose two key differentiators in resilience definitions, the first being the ability
of a system to withstand a disturbance without changing (whether by improvement or deterioration),
implying that no damage is done, and the second differentiator is the ability of the system to recover
when damage has occurred.
Maguire and Cartwright (2008) identify three views of resilience: resilience as stability, resilience as
recovery and resilience as transformation.
Manyena et al (2011) highlight that disasters are accompanied by change, and that instead of resilience
involving ‘bouncing back’ after an event, it should involve ‘bouncing forward’ and ‘moving on’. They argue
that ‘bouncing back’ does not signal change, and may involve returning to the conditions that may have
caused the disaster in the first place. They conclude that resilience can be viewed as the ‘intrinsic capacity
of a system, community or society predisposed to a shock or stress to bounce forward and adapt in order
to survive by changing its non-essential attributes and rebuilding itself’.
Bruneau et al (2003) illustrate the notion of resilience as it relates to the measure of seismic resilience.
Figure 4.1 demonstrates conceptually the measure of resilience over time from a single event (at t
0
) and
the restoration of ‘100%’ level of service (at t
1
). The diagram is a simplistic depiction as it does not show
the impacts from gradual changes over time (stress events), nor does it demonstrate adaptation (ie return
to an improved or altered state).
Figure 4.1 Conceptual measure 1 of resilience
Source: Bruneau et al (2003)
Other authors also quantify resilience as a function of the effort and resources required to recover from
the disaster as depicted in figure 4.2. This shows a rapid increase of effort after an event at t
0
followed by
a constant effort until the infrastructure is restored (t
1
) and then a gradual decrease.
Measuring the resilience of transport infrastructure
22
Figure 4.2 Conceptual measure 2 of resilience (recovery effort)
Recent work by Park et al (2013) describes resilience as an emergent property of what an engineering
system does, rather than a static property the system has. This viewpoint leads to different approaches to
dimensioning and building resilience, and focuses on continuous management, adaptation and new
approaches to design. This view is shared by Snowdon (2011) who contends ‘a resilient system accepts
that failure is inevitable and focuses instead on early discovery and fast recovery from failure’. A
fundamental factor in their respective approaches to resilience is the consideration of risk in the context
of ‘unknown’ hazard events, and the differentiation between a ‘resilience’ approach and a ‘risk’ approach.
This is discussed further in section 4.2.
With the above conceptualisations and views in mind, we have summarised a range of definitions:
• ‘Resilience is the capability of a system to maintain its functions and structure in the face of internal
and external change and to degrade gracefully when it must’ (Allenby and Fink 2005).
• ‘Resilience is the ability of systems, infrastructures, government, business and citizenry to resist,
absorb, and recover from or adapt to an adverse occurrence that may cause harm, destruction, or loss
of national significance’ (USDHS 2009a).
• ‘Resilience is the ability to survive a crisis and to thrive in a world of uncertainty’ (Seville 2009).
• ‘[Resilience is the ability of] a locale to withstand an extreme natural event without suffering
devastating losses, damage, diminished productivity, or quality of life and without a large amount of
assistance from the outside community’ (Mileti 1999).
• ‘The ability of a social or ecological system to absorb disturbances while retaining the same basic
structure and ways of functioning, the capacity for self-organisation, and the capacity to adapt to
stress and change’ (Solomon et al 2007).
Finally, it is necessary to highlight the NIP definition, which is as follows:
The concept of resilience is wider than natural disasters and covers the capacity of public,
private and civic sectors to withstand disruption, absorb disturbance, act effectively in a
crisis, adapt to changing conditions, including climate change, and grow over time (NIU
2011).
This definition acknowledges that the service the infrastructure delivers will be disrupted, due to the
infrastructure undergoing damage; however, the service is able to reduce the possibility of failure, adapt
and recover from a disruptive event and/or gradual external changes over time. It is considered the
definition is broad enough to encompass an approach consistent with the more recent views of Park
(2013) and Snowdon (2011) who recommend an approach that allows for ‘unknown’ as well as ‘known’
4 What is resilience?
23
hazards, as discussed above. It also could cover the ‘bounce forward’ idea proposed by Manyena et al
(2011).
As such, and for the purposes of this study, the NIP definition is considered appropriate.
4.1.1 Resilience, vulnerability and sustainability
There is a vast array of literature available on defining resilience and the relationship of resilience to other
commonly used (and often misunderstood) terms such as vulnerability and sustainability.
There are a variety of views on how they interact.
Vulnerability is a key concept for both disaster risk and climate change adaptation. It can be described as
a deficit concept (Malone 2009) and as such, resilience and vulnerability could be considered as two ends
of a spectrum (Levina and Tirpak 2006) with resilience being a positive measure. Folke et al (2002) termed
vulnerability the ‘flip-side’ of resilience.
On the other hand, vulnerability can be viewed as a component of resilience (Maguire and Cartwright
2008), or indeed as suggested by Brabhaharan (2006), resilience is a function of vulnerability (and other
factors). Therefore, the infrastructure can be assessed as vulnerable but still have a level of resilience due
to other influencing organisational, financial and social dimensions.
The following definition of vulnerability, adapted from UNDRO (1980) and UNISDR (2004), was adopted for
this study.
Vulnerability refers to the propensity of exposed elements such as human beings, their
livelihoods, and assets to suffer adverse effects when impacted by hazard events.
As for sustainability and resilience, Grubinger (2012) argues that the concepts overlap over a time scale,
with resilience being achieved in the short term via adaptation, and leading into sustainability over the
medium term through mitigation and ultimately reaching sustainability through transformation. This
could be illustrated through considering the example of sea-level rise due to climate change. Resilience to
sea-level rise-related hazards could be achieved in theory through a variety of structural, planning and
response activities/adaptations (such as relocation of houses and building of defences). Mitigation could
be achieved by lowering carbon dioxide emissions through reducing or substituting fossil fuel use. Finally,
sustainability would be the outcome of a long-term transition to a low (zero) carbon society.
Zolli (2012) proposes a relationship along similar lines and suggests that where sustainability aims to put
the world back into balance, resilience looks for ways to manage an imbalanced world. He goes on to
suggest that resilience is a more pragmatic and politically inclusive response to pressures – ‘rolling with
the waves instead of trying to stop the ocean’.
Sustainability has not been considered in this study, due to the specific focus on transport systems and a
desire to simplify the approach where possible. Recommendations are made, however, for future work in
this area in order to generate more clarity on the subject and identify opportunities to deliver benefits in
both a sustainability and resilience context (refer chapter 9).
For further discussion on the above relationships, refer to appendix C.
4.2 Hazards, risk and resilience
In order to further understand resilience, it is useful to consider its significance to both hazards and risk.
Measuring the resilience of transport infrastructure
24
Recent natural and technological catastrophes have highlighted a) a failure to predict extreme events, and
b) an inability to understand the complex systems involved and the potential range of failure possibilities.
Park et al (2013) emphasise our ignorance: ‘not the assumption that future events are expected, but that
they will always be unexpected’.
In general, hazards can be categorised into three general types: natural, technological and social/political
in nature. These can be further broken down into ‘stress’ events, that are long-term and gradual change
processes, and ‘shock’ events, that are short-term and sudden change processes. Appendix E contains
examples of the various types of hazards in these categories.
Hazards can also be classified as ‘known’ (or predictable) and ‘unknown’. Unknown’ hazards are also
called ‘rare events’, or in some instances, ‘black swans’. Taleb (2008) developed three characteristics to
describe black swan events:
1 They lie outside the realm of regular expectations, because nothing in the past can convincingly point
to their possibility.
2 They carry an extreme impact.
3 In spite of their outlier status, human nature causes people to concoct explanations for the occurrence
after the fact, making it explainable and predictable.
Furthermore, due to the range of complex interdependencies involved, there is a wide variety of possible
failure modes. In general, we have a poor understanding of how failures can propagate and amplify within
and across complex systems. Risks can emerge through non-linear interactions among system
components and generally only become observable after they occur. Hollnagel (2011) classifies failure
modes into three general types as summarised below (and discussed further in appendix E):
• simple, linear failure: failure of one asset triggering the failure of an interconnected and successive
asset (cascade)
• complex, linear failure: failure results from a combination of failures and latent conditions – often
hidden dependencies
• complex, non-linear failure: failure results from expected or unexpected combinations (concurrence)
of events.
Historically, a risk analysis approach has been used to identify risks and then develop
management/mitigation approaches. However, as many hazards and failure modes are unknown, risk
analysis becomes inadequate, and arguably impossible (Park et al 2013). In short, risk analysis requires
the hazards to be identifiable, and therefore, to prepare for the unexpected. An alternative (and
complementary) approach is required to consider these unpredictable events.
Some key differences in a traditional ‘risk-based’ approach versus a ‘resilience’ approach are as follows:
1 A risk-based approach looks to mitigate failure through probability and scenario-based analysis of
known hazards. A resilience approach looks to minimise the consequences of failure through
investigating scenarios with unidentified causes.
2 A risk-based approach would involve incrementally modifying existing designs in response to
emerging hazards, whereas a resilience approach would involve adapting to changing conditions, and
potentially allowing controlled failure (‘safe-to-fail’ design) at a sub-system level to reduce the
possibility of broader loss of function within the larger system (Park et al (2013) and Snowden (2011).
4 What is resilience?
25
These ‘risk’ and ‘resilience’ approaches are considered complementary and applicable in different
circumstances. They are not considered mutually exclusive, and their use will depend on the context of the
analysis being undertaken and the understanding of the relevant hazard. This is discussed in section 5.1.
4.3 Dimensions and principles of resilience
To further understand resilience, researchers have developed a range of dimensions, principles and
measures of resilience. Their relationship to the NIP attributes is indicated below. By defining and
categorising these dimensions and principles, the broad framework elements can be built, from which
meaningful and practical measures can then be developed. This section discusses dimensions and
principles, with chapter 5 addressing measures.
Figure 4.3 Relationship between NIP attributes and dimensions, principles and measures of resilience
The NIP 2011 defines a series of eight ‘attributes’ which help guide the definition and application of
resilience in practice. These are summarised in table 4.1.
Table 4.1 National Infrastructure Plan resilience attributes
NIP 2011 attribute Description
1 Service delivery
There is a focus on national, business and community needs in the immediate and
longer term. Resilient infrastructure delivers a level of service sufficient to meet
public and private needs, ensuring community viability.
2 Adaptation
National infrastructure has the capacity to withstand disruption, absorb
disturbance, act effectively in a crisis, and recognises changing conditions over
time.
3 Community preparedness
Infrastructure providers and users understand the infrastructure outage risks
(hazards) they face and take steps to mitigate these. Aspects of timing, duration,
regularity, intensity and impact tolerance differ over time and between
communities, and must be taken into account.
4 Responsibility Individual and collaborative responsibilities are clear between owners, operators,
users, policy-makers and regulators. Responsibility gaps are addressed.
5 Interdependencies A systems approach applies to identification and management of risk (including
consideration of interdependencies, supply chain and weakest link vulnerabilities).
6 Financial strength There is financial capacity to deal with investment, significant disruption and
changing circumstances. This includes available funds, the awareness of financiers
and insurers, continuing capital investment and maintenance expenditure.
Measuring the resilience of transport infrastructure
26
NIP 2011 attribute Description
7 Continuous On-going resilience activities provide assurance and draw attention to emerging
issues, recognising that infrastructure resilience will always be a work in progress.
Includes effective, on-going monitoring and auditing processes feeding back into
continuous improvement.
8 Organisational performance Leadership and culture are conducive to resilience, including resilience ethos,
situational awareness, management of keystone vulnerabilities and adaptive
capacity. Future skills requirements need to be addressed.
Source: NIU (2012)
These attributes are considered the over-arching considerations that then guide the development of a
resilience framework. The dimensions, principles and measures developed in this study will necessarily be
more specific and quantifiable. These are discussed further in the following sections.
4.3.1 Dimensions of resilience
It is important to understand different dimensions in order to develop an appropriate approach to
measuring and improving resilience.
USDHS (2009a) divides resilience dimensions into ‘hard’ and ‘soft’ systems, hard systems pertaining to the
technical and mechanical capabilities of infrastructure and organisations, and soft relating to the human
needs, behaviours and psychology within organisations and communities.
VTPI (2010) adopts a slightly different approach and breaks down dimensions of transport resilience into
five levels: individual, community, design, economic and strategic planning.
Bruneau et al (2003) developed four dimensions of resilience: technical, organisational, social and
economic (TOSE). They note that these four TOSE dimensions cannot be measured by any single
performance measure, instead they require different measures for each system under analysis.
A final, more simplistic, example is that developed by the US National Infrastructure Advisory Council
(NIAC 2010), which distinguishes between those practices related to people and processes and those
related to the structure of infrastructure and assets.
Both the NIAC dimensions and the TOSE dimensions serve as useful and relevant constructs for
understanding the high-level dimensions of resilience. They effectively encompass and summarise the
dimensions developed by VTPI (2010) and USDHS (2009a).
It is proposed that of the four TOSE dimensions, only the technical and organisational elements be
utilised, as illustrated in table 4.2. Because of the narrow focus on the transport system, the social and
economic dimensions are considered implicit as the network itself provides a vital social and economic
service, and its technical or organisational resilience will inherently provide flow-on social and economic
resilience. Economic considerations relating to the operator, and funding to deliver resilience, will be
covered within the organisational dimension.
Significant work has been undertaken in Australia (Governmental Resilience Expert Advisory Group) and
New Zealand (Resilient Organisations) to understand and develop more resilient organisations, especially
within the critical infrastructure and lifelines sectors.
It is vital that organisational resilience is given equal consideration to the resilience of the physical
infrastructure (technical resilience). Not only does this provide for improved outcomes for the overall
sector, but can also deliver enhanced leadership, enhanced reputation, lower costs, increased innovation
and many other tangible benefits (Commonwealth of Australia 2011).
4 What is resilience?
27
Table 4.2 Dimensions of resilience
Resilience dimension Description
Technical The ability of the physical system(s) to perform to an acceptable/desired level when
subject to a hazard event (Bruneau et al 2003).
Organisational The capacity of an organisation to make decisions and take actions to plan, manage
and respond to a hazard event in order to achieve the desired resilient outcomes
(adapted from Bruneau et al 2003).
Seville et al (2006) write that a resilient organisation is one that is ‘still able to
achieve its core objectives in the face of adversity’. They identify three aspects to
building resilience in organisations: a) reducing the size and frequency of crises
(vulnerability), b) improving the ability and speed of the organisation to manage
crises effectively (adaptive capacity), and c) an acute awareness of risk and an ability
to manage strategic risks as a process and not an event.
Source: Bruneau et al (2003)
The next section discusses specific principles of resilience that may apply to the dimensions above.
4.3.2 Principles of resilience
In previous sections we have outlined the complexity involved in understanding and defining resilience, as
well as the complexity in types of hazards and failure modes that can affect infrastructure. A number of
authors have developed comprehensive lists of principles for achieving resilience to enable common
understanding and direct efforts to improving resilience. This section discusses general principles of
resilience and then provides further detail specifically around organisational resilience principles.
4.3.2.1 General resilience principles
Foster (1997) identifies that in general, resilient systems are independent, diverse, renewable and
functionally redundant, with reserve capacity achieved through duplication, interchangeability and
interconnections.
VTPI (2001), Comfort (1999) and Foster (1997) have developed principles which include: redundant,
diverse, efficient, autonomous, strong, adaptable and collaborative.
Bruneau et al (2003) determine four principles: robustness, redundancy, resourcefulness and rapidity. To
these, NIAC (2010) adds the principle of ‘adaptability’ into incident response planning. Figure 4.4 clarifies
how these can apply prior, during and after an event.
Measuring the resilience of transport infrastructure
28
Figure 4.4 Resilience principles in sequence
Source: NIAC 2010
CDEM (2005) has established 4 R’s which are reduction, readiness, response and recovery. While these
overlap, they are more applicable to the field of emergency management and the cycle before, during and
after an event than to a specific resilience assessment.
Madni et al (2009) emphasise that resilience in engineering systems is more properly thought of as a
characteristic of how the system behaves (process), as opposed to a property that the system has (state).
Park et al (2013) acknowledge this and have established three overarching principles as follows, spanning
both the technical and organisational dimensions:
• Continuous management: Due to the unpredictability of complex systems, a resilience assessment
demands a constant, recursive process, often across multiple organisations. This process involves four
components: sensing, anticipation, adaptation and learning.
• Recognition of incompleteness: Complex systems are characterised by inherent uncertainty and
incompleteness across a variety of areas: internal and external factors affecting design and operation,
uncertainty in variability of shocks, and types and visibility of interdependencies.
• New approaches to design: Resilience requires a new approach to design thinking. Standard design
approaches tend to be based on incremental adaptations of previous approaches in response to a
failure. These approaches are generally inflexible and are difficult to change if unexpected conditions
are found. Resilient design requires new thinking and a departure from existing practices. Where a
traditional ‘risk-based’ design would result in a design that is resistant to hazards, a resilient design
would embrace uncertainty and failure via anticipation and adaptation (Anderies et al 2007).
Additionally, whereas a risk-based approach would typically generate a ‘fail-proof’ design (able to
withstand a range of known hazards), a resilience-based approach would account for unpredictability
through a ‘safe-to-fail’ design (Snowden 2006; Park et al 2013). This would entail planned, predictable
modes of failure that have been anticipated and designed for, as opposed to failure modes in a fail-
proof design which can often be brittle and catastrophic.
As can be seen many common themes run through the types of principles associated with resilience.
However, paradoxically many of these are combinations of apparent opposites: redundancy and efficiency,
diversity and interdependence, robustness and safe-to-fail, autonomy and collaboration, planning and
adaptability – adding weight to the importance of careful definitions and delineation between assessment
areas when building a framework.
4 What is resilience?
29
4.3.2.2 Organisational resilience principles
In regard specifically to organisational resilience, Commonwealth of Australia (2011) and Resilient
Organisations (various papers) have identified three core behavioural principles (with a range of indicator
subsets) which help define resilient organisations, as summarised in table 4.3 below.
Table 4.3 Organisational resilience – behavioural principles
Behavioural principle
(and indicators)
Description
Leadership and culture
(Leadership, staff
engagement, decision
making, situational
awareness, innovation and
creativity)
A resilient organisation:
• develops an organisational mind-set/culture of enthusiasm for challenges, agility,
flexibility, adaptive capacity, innovation and taking opportunity
• fosters the above through developing trust, clear purpose and empowerment of
employees
• promotes a consistent and transparent organisational commitment to a resilience
culture, values and vision, including a belief of ‘one in – all in’
• encourages increased personal resilience by employees
• has board members and senior executives who engage and provide leadership
appropriate to their position on organisational resilience.
Networks
(Breaking silos, leveraging
knowledge, effective
partnerships, internal
resources)
A resilient organisation:
• establishes relationships, mutual aid arrangements and regulatory partnerships
• understands an organisation’s community interconnectedness and its vulnerabilities
across all aspects of supply chains and distribution networks
• promotes open communication and mitigation of internal/external silos.
Change ready
(Planning strategies, unity
of purpose, proactive
posture, stress testing
plans, innovation and
creativity)
A resilient organisation:
• promotes proactive anticipation and preparation for future challenges
• develops a forewarning of disruption threats and their effects through sourcing a
diversity of views, increasing sensitivity and alertness, and understanding social
vulnerability
• promotes empowered and broadly embraced organisational and individual self-
efficacy, as well as enthusiasm for finding effective solutions to complex challenges
• promotes requisite decision making using both rational and intuitive abilities
• promotes critical reflective learning, lesson retention, knowledge sharing and
continuous improvement.
Source: Resilient Organisations (2012)
4.3.2.3 Summary of chosen resilience principles
To conclude this section, the following broad principles have been summarised which encompass the
views of the various authors across both technical and organisational dimensions, and which are proposed
to form the basis of the framework to measure the resilience of the transport system.
From a technical perspective, Bruneau’s principles of robustness and redundancy are considered to
broadly encapsulate the range of ideas proposed by other authors, while the concept of ‘safe-to-fail’
proposed by Park et al and Snowden is included as a third technical principle. The concept of
‘independent’ as proposed by Foster (or ‘autonomous’) has not been included explicitly as a technical
principle. For transport infrastructure, this may, in theory, be applicable to powered systems (eg lights)
which could be powered by independent supplies; however, it is suggested (for practical reasons) that the
provision of independent supplies be considered instead in a back-up context as ‘redundancy.
Measuring the resilience of transport infrastructure
30
From an organisational perspective, the three principles developed by Resilient Organisations have been
adopted. These are considered to broadly encompass the principles developed by others, as discussed
above.
Table 4.4 Proposed principles of resilience for the transport system
Dimension Principle Definition and justification
T
e
c
h
n
i
c
a
l
Robustness Strength, or the ability of elements, systems and other units of analysis, to
withstand a given level of stress or demand without suffering degradation or loss
of function (Bruneau et al 2003).
Redundancy The extent to which elements, systems, or other infrastructure units exist that are
substitutable, ie capable of satisfying functional requirements in the event of
disruption, degradation, or loss of functionality (Bruneau et al 2003). For
simplification, this is assumed to include considerations of ‘diverse’ and ‘reserve
capacity’. The concept of ‘independent/autonomous’ is included here, only in the
context of back-up provision, as discussed above.
Safe-to-fail The extent to which innovative design approaches are developed, allowing (where
relevant) controlled, planned failure during unpredicted conditions, recognising
that the possibility of failure can never be eliminated. This may involve new
approaches to design, to complement traditional, incremental risk-based design
(Park et al 2013).
O
r
g
a
n
i
s
a
t
i
o
n
a
l
Change readiness* The ability to sense and anticipate hazards, identify problems and failures, and to
develop a forewarning of disruption threats and their effects through sourcing a
diversity of views, increasing alertness, and understanding social vulnerability
(Resilient Organisations 2012). Also involves the ability to adapt (either via
redesign or planning) and learn from the success or failure of previous adaptive
strategies (Park et al 2013). This learning is also conceptualised by Manyena et al
(2011) who in their ‘bounce-forward’ idea of resilience, identify moving from
single-loop or error-corrective learning, to double-loop, organisational learning,
where the values, assumptions and policies that led to the actions in the first place
are questioned.
The capacity to mobilise resources when conditions exist that threaten to disrupt
some element, system, or other unit of analysis; resourcefulness can be further
conceptualised as consisting of the ability to apply material (ie monetary, physical,
technological, and informational) and human resources to meet established
priorities and achieve goals (Bruneau et al 2003).
Networks The ability to establish relationships, mutual aid arrangements and regulatory
partnerships, understand interconnectedness and vulnerabilities across all aspects
of supply chains and distribution networks, and; promote open communication
and mitigation of internal/external silos (Resilient Organisations 2012).
Leadership and
culture
The ability to develop an organisational mind-set/culture of enthusiasm for
challenges, agility, flexibility, adaptive capacity, innovation and taking opportunity
(Resilient Organisations 2012).
*Readiness encompasses the change-ready concepts developed by Resilient Organisations (2012), along with the
concept of ‘resourcefulness’ developed by Bruneau et al (2003) and Park et al (2013).
4 What is resilience?
31
4.4 Summary
4.4.1 Main points
The NIP resilience definition is considered appropriate: ‘The concept of resilience is wider than natural
disasters and covers the capacity of public, private and civic sectors to withstand disruption, absorb
disturbance, act effectively in a crisis, adapt to changing conditions, including climate change, and grow
over time’ (NIU 2011).
The NIP attributes are considered relevant; however, we do not suggest they be used to categorise
resilience dimensions and principles. In subsequent sections, the NIP attributes are mapped to the chosen
framework principles for completeness.
It is suggested that the broad dimensions of technical and organisational be used, along with the
principles of robustness, redundancy, safe-to-fail, change readiness, networks, leadership and culture.
4.4.2 Relevance to framework development
The framework has been built around the broad dimensions as follows:
• technical (robustness, redundancy, safe-to-fail)
• organisational (change readiness, networks, leadership and culture).
Measuring the resilience of transport infrastructure
32
5 How can we measure resilience?
As illustrated in figure 4.3, measures for resilience can be distilled from an analysis of dimensions and
principles. In general terms, measures need to be broad enough to allow application across a variety of
scales, including transport modes. They also need to be transparent and quantifiable (although, this may
be in a relative sense as opposed to being an exact determination).
Past studies have fallen generally into two groups – those which develop a conceptual (qualitative)
framework for measuring resilience, and those which have attempted to develop quantitative metrics
(indices) through more detailed analysis and modelling. We also note the difference between frameworks
that assess resilience after a hazard event, and those that assess resilience before an event.
Initially, however, we explore the question ‘resilience to what?’ We discuss what types of hazards are
relevant and how a resilience assessment could consider consequence as opposed to the hazard itself.
5.1 Resilience to what?
As discussed in section 4.2, there is a wide range of hazards, hazard types and failure modes that could
affect a given piece of infrastructure or the transportation network. However, a resilience assessment also
requires an awareness that the hazard itself may be unpredictable (Park et al 2013) and the organisation
needs to think beyond typical disaster scenarios (Brunsdon and Dalziell 2005).
As such, it is useful to move from consideration of hazards (either via probability or scenario analysis) to
consideration of consequences which specifically relate to the loss of service as well as other impacts.
These consequences can relate to a non-specified hazard event, which could apply to any (or all) hazard
types. Brunsdon and Dalziell (2005) provide some consequence scenarios which are considered applicable
and have been adapted for the transport context:
• Regional event: significant physical damage to transport infrastructure, coupled with severe
disruptions to other lifeline services such as electricity, water and telecommunications. An example of
this type of event may be a major earthquake or flood.
• Localised event: a transport-specific incident resulting in loss of life, severe disruption to normal
operations and reputation impacts. The intense focus of media and regulatory agencies requires the
organisation to focus on managing stakeholder perception as well as the physical response and
recovery from the event. Examples may be a collapse of a transport structure, or a hazardous spill
affecting the immediate locality.
• Societal event: a societal event which may cause unexpected impacts or demand on the transport
system. In this case, all physical infrastructure is intact; however, the transport system is unable to cope
with demand. Examples may include: 1) a surge in traffic demand due to a specific event, or a major
gathering of people, 2) growth in demand over time, 3) growth in public transport demand due to, say,
fuel price rises, 4) an illness pandemic (eg influenza or SARS), meaning operational staff are unavailable.
• Distal event: impacts transport operations through key suppliers or interdependencies. This
consequence scenario can identify the ways the transport system and related organisations may be
affected through its networks of inter-organisational relationships. Examples may be the failure of a
key dependent utility (power, telecommunications, water), failure of a key supplier, or an international
shortage of key resources.
5 How can we measure resilience?
33
Note that such an approach to considering the consequences of unpredictable events should not
necessarily replace an assessment of known (or predictable) hazards using a more standard risk-based
approach.
There may be certain situations where a specific hazard assessment would be appropriate, for example,
where critical assets or sections of network are required to be assessed and hazards are well understood.
In these cases both approaches are required within the overall resilience framework. These have been
distinguished into two categories called ‘all-hazards’ and ‘specific-hazard’.
5.1.1 An all-hazards vs specific hazard approach
To summarise the above discussion, we consider there is merit in undertaking both an all-hazards
approach as well as a specific-hazard approach, depending on the context of the evaluation.
An all-hazards approach to resilience would involve a high-level assessment looking at resilience measures
in response to all hazards in general, and would consider a relevant event scenario as detailed above
(regional, local, societal, distal).
A specific-hazard assessment would be more detailed, however, and therefore might be appropriate for
certain critical assets. This would involve identifying the complete range and type of potential scenarios as
described above, and assessing the risk (likelihood and consequence) of them occurring. The resilience
assessment and response could then be tailored accordingly. Appropriate methods could be used to identify
hazards due to known ‘rare events’ and also non-linear modes of failure involving interdependencies.
The following sections outline approaches to measurement of resilience in both a qualitative and
quantitative context, and recommend a preferred approach.
5.2 Conceptual/qualitative frameworks
These frameworks typically remain at a higher level and set out principles (such as those outlined in
section 4.3) from which resilience can be assessed. Some examples are described below.
Bruneau et al (2003) developed a range of performance criteria (measurement categories) relating to
seismic resilience. Measures were developed specifically for each dimension (TOSE) and related to each
principle (robustness, redundancy, resourcefulness and rapidity) as summarised in table 5.1.
Table 5.1 Seismic resilience measures example
Performance criteria
Performance measures Robustness Redundancy Resourcefulness Rapidity
Technical Damage avoidance
and continued
service provision
Backup/duplicate
systems, equipment
and supplies
Diagnostic and damage
detection technologies
and methodologies
Optimising time to
return to pre-event
functional levels
Organisational Continued ability to
carry out designated
functions
Backup resources to
sustain operations
(eg alternative sites)
Plans and resources to
cope with damage and
disruption (eg mutual
aid, emergency plans,
decision support
systems)
Minimise time
needed to restore
services and
perform key
response tasks
Social Avoidance of
casualties and
disruption in the
community
Alternative means of
providing for
community needs
Plans and resources to
meet community needs
Optimising time to
return to pre-event
functional levels
Measuring the resilience of transport infrastructure
34
Performance criteria
Performance measures Robustness Redundancy Resourcefulness Rapidity
Economic Avoidance of direct
and indirect
economic losses
Untapped or excess
economic capacity
(eg inventories,
suppliers)
Stabilising measures (eg
capacity enhancement
and demand
modifications, external
assistance, optimising
recovery strategies)
Optimising time to
return to pre-event
functional levels
Source: Bruneau et al 2003
Brabhaharan (2006) also developed a method to establish ‘performance criteria’ and example metrics by
which elements of the transport system could be measured after an event. These were based on specific
levels of service requirements following hazard events, and performance criteria developed for specific
critical sections of the network by relevant stakeholders. Some example criteria are shown in table 5.2.
These serve as useful example measures; however, it is noted that these apply to a post-event situation.
Similar, qualitative measures could be developed for use before an event.
Table 5.2 Example performance criteria
Service provided Priority/criticality of
relevant road link
Level of service Measure
1a. Temporary access to
emergency services for
emergency service vehicles
Very high Restore temporary road access
to hospitals and emergency
centres.
Within two hours
1b. Temporary access to
emergency services for
emergency service vehicles
High Restore temporary road access
to hospitals and emergency
centres identified by the
district health board
Within two days
2a. Access to lifeline utilities N/A (all are assumed
equal)
Restore 4x4 road access to
power, water and
telecommunication utilities for
inspection and repair.
Within three days.
3a. Network availability High Re-open one lane for heavy
trucks and buses
Within 24 hrs.
3b. Network availability Medium Re-open one lane for heavy
trucks and buses
Within 36 hrs.
3c. Network availability Low Re-open one lane for heavy
trucks and buses
Within one week
Source: Brabhaharan (2006)
Other examples of conceptual transport-related frameworks include those developed by Heaslip et al
(2009), Murray-Tuite (2006), Mostashari et al (2009). All of these are qualitative in nature and propose a
range of subjective criteria to assess.
Dantas and Giovinazzi (2010) developed a benchmarking framework to measure the readiness of road
controlling authorities to meet their obligations under the Civil Defence and Emergency Management Act
2002. The self-assessment tool developed, included a set of key performance indicators, which are
representative of the critical success factors in emergency management, and benchmarked performance in
relation to the 4Rs (reduction, readiness, response and recovery).
5 How can we measure resilience?
35
Lee et al (2013) developed a framework and survey tool for organisations to use to identify their strengths
and weaknesses and to develop and evaluate the effectiveness of their resilience strategies and
investments. The survey consisted of a range of questions across 13 indicators which are shown as
subsets within table 4.3.
5.3 Quantitative approaches
A number of authors have developed detailed quantitative methods for measuring the resilience of specific
networks. In many cases these have produced a ‘resilience index’ resulting from the modelling of
networks and possible failure modes.
In general terms, many of the methods set out to a) evaluate the failures in levels of service due to the
impact of an event, b) evaluate the time to restore an acceptable level of service to a network and c)
compare the recovered system performance as a result of a strategy (intervention) with the system
performance without the strategy.
Approaches used to undertake the analysis vary and include the use of network models, GIS analysis,
fuzzy systems approaches and others. Urena Serulle (2010) summarised a range of previous analyses
undertaken and related field and methodology employed, which is shown in table 5.3.
Table 5.3 Summary of previously proposed quantitative assessments of resilience
Author Field Proposed methodology
Hamad and Kikuchi
(2002)
Transportation
engineering
Developed a measure of traffic congestion based on two
conventional transportation metrics, travel speed and delay.
A fuzzy inference approach was implemented to combine
travel speed and delay into one single index. The result was
a congestion index that ranges from 0 to 1, where 0 is the
best condition and 1 the worst.
Brenkert and Malone
(2004)
Social study Proposed a set of 17 quantitative indicators that allow
comparisons of different levels of localities (regional, states,
cities, etc) in terms of their vulnerability and resilience to
current and changing climate.
Mayunga (2007) Social study Obtained a weighted average of the resilience elements
(social capital, human capital, economic capital, physical
capital and natural capital) to obtain a single community
disaster resilience index.
Heaslip et al (2010) Transportation
engineering
Ten measurable variables were used to define four basic
network performance indexes (network availability, traveller
perception, transportation cost and network accessibility).
These four indexes were then combined using fuzzy
inference logic into a single network service performance
index, which served as a base resilience index.
Source: Serulle 2010
5.4 Recommended measurement approach
Based on the above research of measurement approaches, table 5.4 summarises each type of approach.
Measuring the resilience of transport infrastructure
36
Table 5.4 Summary of qualitative and quantitative measurement approaches
Qualitative approach Quantitative approach
Flexibility Provides a flexible approach that can
be adapted to a range of situations,
scales and conditions.
Is typically applied only at a smaller
geographical scale and at a more
detailed level.
Data requirements Can be applied with complete or
incomplete data sets. Relies on
subjective assessments in many
cases.
Typically requires large, accurate data
sets.
Computational requirements None/minimal. Requires significant computational
effort.
Results A relative, subjective assessment –
often using a ranking scale
Typically delivers a discrete resilience
index or measure by way of network
modelling or fuzzy logic modelling.
Ease of implementation Simple Difficult
Use in targeting resilience
improvements
Useful; however, is very much
related to the design of the
framework, how it is implemented,
and subjectivity of the scores given.
Can be accurate for the network
analysed.
Useful in wider organisational
resilience assessments and
engagement
Yes No
Useful in assessing physical network
asset resilience
Yes Yes
Based on the above, we suggest that a broadly qualitative approach would better suit the Transport
Agency’s requirements for a practical and flexible framework. We note that there may be some
quantitative measures within the overall framework; however, generally speaking, we propose a qualitative
assessment.
The approach will be based around:
• dimensions of resilience – technical and organisational
• principles of resilience – robustness, redundancy, safe-to-fail, readiness, continuous management,
leadership and culture, networks.
5.5 Summary
5.5.1 Main points
Either an ‘all-hazards’ or ‘hazard-specific’ approach could be used for measuring resilience. The latter
would be much more detailed and it may be appropriate in certain situations where specific hazards are
well understood.
Historically, both qualitative and quantitative approaches have been used for measuring resilience.
Quantitative approaches tend to be less flexible, time consuming and appropriate for more narrow
assessments of networks and systems. They are data intensive and can be difficult to implement.
5 How can we measure resilience?
37
Qualitative assessments are, by nature, more subject to interpretation, but are flexible in terms of scale
and context, and can provide wider process and organisational benefits due to the necessary involvement
of operators and managers.
There are also broadly qualitative frameworks which contain measures that are more quantitative in
nature.
5.5.2 Relevance to framework development
A broadly qualitative approach to measuring resilience is proposed, with a range of specific
measures/categories based on the dimensions and principles developed in the previous section.
The framework should be able to be implemented at a general ‘all-hazards’ level or a ‘specific-hazard’
level.
Measuring the resilience of transport infrastructure
38
6 A proposed measurement framework for
transport system resilience
This chapter summarises a proposed practical framework for measuring resilience based on the
dimensions and principles developed in previous sections. For each step, explanation and detail is
provided to justify the chosen approach.
The process described in figure 6.1 includes an initial determination of the context of the resilience
assessment, followed by a detailed assessment using a wide range of resilience measures, which combine
to generate a resilience score from 4 (very high resilience) to 1 (low resilience):
4 Very high resilience – meets all requirements
3 High resilience – acceptable performance in relation to a measure(s), some improvements could be
made
2 Moderate resilience – less than desirable performance and specific improvements should be prioritised
1 Low resilience – poor performance and improvements required.
The following sections describe each of these processes in more detail.
6 A proposed measurement framework for transport network resilience
39
Figure 6.1 Proposed resilience assessment
Measuring the resilience of transport infrastructure
40
6.1 Resilience assessment context
The resilience assessment has been divided into dimensions and principles as determined in chapter 4.
The broad level dimensions used are technical and organisational. Principles of resilience have been taken
as robustness, redundancy, safe-to-fail, change-readiness, networks, and leadership and culture.
Robustness, redundancy and safe-to-fail relate to technical, asset or network considerations while the
remainder relate to the organisational considerations (refer to figure 6.1).
Each of the above four principles has been mapped to the NIP 2011 attributes to ensure that the
framework links to and aligns with the NIU process.
There are a number of cross-cutting themes that influence the context and approach of the resilience
assessment. These are summarised and discussed in the table below.
Table 6.1 Cross-cutting themes
Cross-cutting theme Discussion
All hazards/specific hazard
approach
The assessment can be undertaken in one of two ways:
1 An all-hazards assessment – based on an event due to any (unspecified)
hazard/failure, which could be either known or unknown. The event could
be regional, local, societal or distal (section 5.1).
2 A hazard-specific assessment could be undertaken. This would involve
identifying the relevant known hazard types and assessing the resilience to
each.
Scale of assessment The framework will allow assessment at various scales: regional, network or
asset. Measures have been developed for each and the user can filter the
questions accordingly. Regional assessments could be aggregated to a national
indicator for NIU purposes.
Shock event or stress event The framework will be able to evaluate both short-term shock events (eg
earthquakes and tsunamis) and longer-term stress events (eg climate change
related).
Stress events should be considered as part of a hazard-specific assessment (see
above) and if required, a risk-assessment could be undertaken as well to
understand likelihood and consequence of occurrence.
6.2 Resilience measures
A range of measurement categories are suggested based on the six resilience principles – as discussed in
section 5.2. Within these categories, specific measures have been developed. It is important to note that
each category covers a range of parameters associated with that measure.
The measurement categories are described in table 6.2 and map to the NIP resilience attributes as shown.
Each technical principle has been divided into categories of structural, procedural and interdependencies
as these are thought to encapsulate the main types of relevant measures. Organisational principles have
been divided into categories based on those proposed by Resilient Organisations (2012) and Lee et al
(2013), as well as some additional categories suggested by the authors of this report.
6 A proposed measurement framework for transport network resilience
41
Table 6.2 Summary of measurement categories
Principle Measurement category Description
Technical
Robustness
(NIP attributes: service
delivery, adaptation,
Interdependencies)
Structural Physical measures relating to asset/network design,
maintenance and renewal
Procedural Non-physical measures relating to existence, suitability and
application of design codes, guidelines
Interdependencies This relates to upstream dependencies (refer section 3.2) and
their relative robustness in both a structural and procedural
sense
Redundancy
(NIP attribute: adaptation,
Interdependencies)
Structural Physical measures relating to network redundancy, alternate
routes and modes and backup supplies/resources
Procedural Non-physical measures relating to existence of diversion and
communication plans
Interdependencies
This relates to upstream dependencies and their relative
redundancy in both a structural and procedural sense.
Safe-to-fail
(NIP attribute: adaptation)
Structural The extent to which innovative design approaches are
implemented, allowing (where relevant) controlled failure
during unpredicted conditions. This may complement
traditional, incremental risk-based design (Park et al 2013).
Procedural The extent to which safe-to-fail designs are specified in
design guidelines.
Organisational
Change readiness
(NIP attributes:
community preparedness,
responsibility,
interdependencies,
financial strength,
organisational
performance)
Communication and
warning
This relates to the existence and effectiveness of
communication and warning systems
Information and
technology
This relates to the use of technology to monitor events,
communicate, share data, assess resilience etc.
Insurance This relates to the adequacy of insurances for hazard events.
Internal resources The management and mobilisation of the organisation’s
resources to ensure its ability to operate during business-as-
usual, as well as being able to provide the extra capacity
required during a crisis.
Also relates to ensuring roles and responsibilities of all
internal stakeholders are clear and that coordination is
effective.
Planning strategies The development and evaluation of plans and strategies to
manage vulnerabilities in relation to the business
environment and its stakeholders.
Clear recovery priorities An organisation-wide awareness of what the organisation’s
priorities would be following a crisis, clearly defined at the
organisation level, as well as an understanding of the
organisation’s minimum operating requirements.
Proactive posture A strategic and behavioural readiness to respond to early
warning signals of change in the organisation’s internal and
external environment before they escalate into crisis.
Drills and response
exercises
The participation of staff in simulations or scenarios designed
to practice response arrangements and validate plans.
Measuring the resilience of transport infrastructure
42
Principle Measurement category Description
Funding Extent to which funding is available for all elements of
resilience planning including technical and organisational.
Adaptation Constant vigilance and situation awareness (see below) allows
adaptation strategies to be developed. These may be
procedural/planning focused/organisational or technical
(increased robustness, redundancy, or designing for ‘safe-to-
fail’ modes).
Learning Past actions and adaptation strategies are observed and
evaluated in terms of their success in mitigating hazards.
Appropriateness of actions can be assessed and iterations
and changes made.
Networks
(NIP attributes:
interdependencies)
Breaking silos Minimisation of divisive social, cultural and behavioral
barriers, which are most often manifested as communication
barriers creating disjointed, disconnected and detrimental
ways of working.
Leveraging knowledge
(internal and external)
Critical information is stored in a number of formats and
locations and staff have access to expert opinions when
needed. Roles are shared and staff are trained so that
someone will always be able to fill key roles.
Effective partnerships
(external)
An understanding of the relationships and resources the
organisation might need to access from other organisations
during a crisis, and planning and management to ensure this
access. Also relates to clear coordination and understanding
between organisations, and clarity of roles and
responsibilities.
Leadership and culture
(NIP attributes:
organisational
performance)
Situation awareness
(sensing and anticipation)
Staff are encouraged to be vigilant about the organisation, its
performance and potential problems. Staff are rewarded for
sharing good and bad news about the organisation. Early
warning signals are quickly reported to organisational
leaders. Newly incorporated knowledge gained from vigilance
is used to foresee/anticipate crises. This can be used to
develop adaptation strategies.
Leadership Strong crisis leadership to provide good management and
decision making during times of crisis, as well as continuous
evaluation of strategies and work programs against
organisational goals.
Staff engagement and
involvement
The engagement and involvement of staff who understand
the link between their work, the organisation’s resilience, and
its long-term success. Staff are empowered and use their
skills to solve problems.
Decision-making authority Staff have the appropriate authority to make decisions related
to their work and authority is clearly delegated to enable a
crisis response. Highly skilled staff are involved in, or are
able to make, decisions where their specific knowledge adds
significant value, or where their involvement will aid
implementation.
Innovation and creativity Staff are encouraged and rewarded for using their knowledge
in novel ways to solve new and existing problems and for
utilising innovative and creative approaches to developing
solutions.
6 A proposed measurement framework for transport network resilience
43
A detailed database (spreadsheet) has been developed which describes measurements and captures scores
on a scale of 4 (very high level of resilience) to 1 (low resilience). Some example measures for ‘robustness’
are shown in figure 6.2 below, with the complete lists contained in appendix B. The measures can then be
weighted at the discretion of the user to give an aggregate score for a principle (eg robustness) or
dimension (eg technical), or overall.
A summary ‘dashboard’ allows the user to view the various scores and weightings used.
Figure 6.2 Example of resilience measures (for the ‘robustness’ principle)
ROBUSTNESS
Weighted robustness score 2.3
Category Measure Measurement Measurement scale Individual
score
Category
average
Weighting
(%)
Weighted
score
Structural
Maintenance Processes exist to maintain critical
infrastructure and ensure integrity
and operability – as per documented
standards, policies & asset
management plans (eg roads
maintained, flood banks maintained,
stormwater systems are not blocked.
Should prioritise critical assets as
identified.
4 – Audited annual inspection process for critical
assets and corrective maintenance completed when
required.
3 – Non-audited annual inspection process for critical
assets and corrective maintenance completed when
required.
2 – Ad hoc inspections or corrective maintenance
completed, but with delays/backlog.
1 – No inspections or corrective maintenance not
completed.
3.0
2.8 33.33% 94.4
Renewal Evidence that planning for asset
renewal and upgrades to improve
resilience into system networks exist
and are implemented.
4 – Renewal and upgrade plans exist for critical assets,
are linked to resilience, and are reviewed, updated and
implemented.
3 – Renewal and upgrade plans exist for critical assets
and are linked to resilience, however no evidence that
they are followed.
2 – Plan is not linked to resilience and an ad hoc
approach is undertaken.
1 – No plan exists and no proactive renewal or
upgrades of assets.
4.0
Design
Percentage of assets that are at or
below current codes
4 – 80% are at or above current codes
3 – 50-80% are at or above current codes
2 – 20-50% are at or above current codes
1 – Nearly all are below current codes
3.0
Assessment of general condition of
critical assets across region
4 – 80% are considered good condition
3 – 50-80% are considered good condition
2 – 20-50% are considered good condition
1 – Nearly all poor condition
3.0
Percentage of assets that are in
zones/areas known to have exposure
to hazards
4 – 50% are moderately
exposed
2 – 50-80% are highly exposed
1 – 80% are highly exposed to a hazard
2.0
Percentage of critical assets with
additional capacity over and above
normal demand capacity
4 – 80%+ of critical assets have >50% spare capacity
available
3 – 50-80% of critical assets have >50% available
2 – 20-50% of critical assets have >50% spare capacity
1 – 0-20% have spare capacity.
2.0
In summary, the approach to undertaking the resilience assessment is as follows:
1 Determine the context of the assessment:
a all-hazards or specific hazards (including shock or stress event, rare events etc)
b scale: asset/network/regional context
c shock or stress event.
2 Undertake the assessment using the questions relative to the context above and select scores for
each.
3 Apply weightings to the scores, as required.
4 This will generate resilience scores for categories, principles and dimensions and a total score.
Measuring the resilience of transport infrastructure
44
As a stand-alone assessment, the resilience measurement framework can be applied to generate a relative
score that could be used to compare resilience across assets/networks or regions. However, to provide
additional rigour, other steps could be applied. This is discussed in chapter 7.
6.2.1 Application of weightings
The resilience measurement framework consists of a range of questions across the categories shown in
figure 6.1. Once the relevant questions have been answered, weightings can be applied at the category,
principle or dimension level. These weightings are a percentage and must add to 100% across each group.
The weightings allow the user to place importance to (say) one principle over another. For example, one
may determine that ‘robustness’ is more important than ‘redundancy’ or ‘safe-to-fail’ and as such, allocate
a weighting of 40%:30%:30%.
It is important to note that the weightings are subjective and will be based on user preference. In all
instances, the individual scores for each question can be viewed and interrogated to determine reasons
behind a specific principle or dimension score.
Further guidance on the use of the framework is provided in appendix F.
6.3 Summary
6.3.1 Main points
The resilience measurement framework relates to the dimensions, principles and categories outlined in
previous sections. Specific measures for each category have been developed and are included in appendix B.
Each measure is scored from 4 (very high resilience) to 1 (low resilience), and weightings can be applied at
the category, principle and dimension level to generate aggregate scores if required.
The approach can be applied at various scales and to an ‘all-hazards’ or ‘hazard-specific’ context.
7 Implementation of the framework
45
7 Implementation of the framework
As mentioned in chapter 6, the resilience assessment could be applied as a stand-alone assessment for a
particular asset or region.
However, in order to implement the measurement framework in a systematic manner, additional steps
could be incorporated to determine priorities for intervention. This would include determining:
1 Which infrastructure should be assessed for resilience?
2 What level of resilience is appropriate for a given asset/network?
In order to answer these questions, we need to have an understanding of the criticality of a given asset,
and, if required, an understanding of the risk of a particular hazard occurring. Note, this links directly with
the choice of whether a general ‘all-hazards’ or a ‘hazard-specific’ assessment is chosen.
Figures 7.1 and 7.2 summarise the two alternative approaches.
Figure 7.1 All-hazards: criticality and resilience assessment
Figure 7.2 Hazard specific: detailed risk assessment and resilience assessment
The all-hazards approach would involve an assessment of criticality to determine which assets should be
focused on for the resilience assessment. The related questions within the measurement framework
(appendix B) would be those applicable across all hazard types (or, in other words, as the consequence of
a regional, local, societal or distal event – refer section 5.1). The criticality assessment would identify
which assets merited a certain ‘desired’ level of resilience, and then following a resilience assessment for
these assets, related improvements or interventions could be targeted. The translation from criticality to
‘desired’ level of resilience is summarised in table 7.1.
Table 7.1 Example translation of criticality score to ‘desired’ level of resilience
Criticality score Desired level of resilience
Highly critical Very high (4)
Medium High (3)
Low Moderate (2)
Not critical Low (1)
If further detail was required, a hazard-specific assessment could be undertaken. This would require
understanding which types of hazards would be relevant and their associated likelihoods. In this case, the
output of the risk-assessment would determine the ‘desired’ level of resilience.
Criticality
assessment
Resilience
assessment
Improvements
/ intervention
‘Desired’
resilience
Criticality
assessment
Risk
assessment
Resilience
assessment
Improvements
/ intervention
‘Desired’
resilience
Measuring the resilience of transport infrastructure
46
The Transport Agency currently has a state highway classification system that could be utilised to
determine criticality of assets. Rail system operators and local authorities may also have similar methods
for determining criticality. There are, however, a range of additional considerations that can be
incorporated into a criticality assessment, relating to operational considerations, interdependencies and
specific user/community requirements. More information on this is provided in appendix D.
The Transport Agency also has an established risk assessment approach based on the joint
Australian/New Zealand standard AS/NZS 31000:2009, which could be utilised to determine an overall risk
score relating to the likelihood and consequence of a particular hazard occurring (refer to appendix A for
further detail). Other transport system operators may also have similar approaches.
In order to link to the resilience assessment, the risk assessment would need to specifically address:
1 The likelihood of a particular hazard occurring in a given location/region and the likelihood that it
would impact on a given asset.
2 The consequence of failure of the asset, which would be related to the criticality assessment (ie a
critical asset would have a high consequence if it fails).
The resultant risk score derived from a risk assessment could then translate to a ‘desired’ level of
resilience, as illustrated in table 7.2 (example).
Table 7.2 Example translation of risk score to ‘desired’ level of resilience
Risk score (Transport Agency tool) Desired level of resilience
4 (Extreme) Very high (4)
3 (High) High (3)
2 (Moderate) Moderate (2)
1 (Low) Low (1)
As outlined above, a risk assessment would be undertaken as part of a hazard-specific assessment. In this
case, specific attention would need to be given to the types of hazards and failure causes/modes that may
eventuate (refer sections 4.2 and 5.1).
Types of hazards would include, by definition, known hazards and also, where relevant, an assessment of
‘rare event’ possibilities. This assessment could include a range of activities with experienced operational
staff to:
• identify linkages and interdependencies
• think the unthinkable in terms of rare events and failure modes
• consider the combinations of events that might occur
• consider what is happening elsewhere (horizon scanning)
• be more creative in risk identification and identify events that might be known by others but a ‘black
swan’ to the Transport Agency.
Table 7.3 summarises the ranges of scales of application and the suggested relevant approaches which
could be implemented.
7 Implementation of the framework
47
Table 7.3 Approaches to implementation
Scale Suggested approach Application
Asset 1 Hazard-specific: would involve assessing
the resilience of an asset, and comparing
with a desired level based on risk.
2 All-hazards: would involve assessing the
resilience of an asset, and comparing
with a desired level based on criticality
of the asset.
1 This would enable actions and
interventions to be prioritised across
assets in relation to specific identified
hazards.
2 This would enable actions and
interventions to be prioritised across
assets more generally and in relation
to ‘all hazards’.
Network/route 1 Hazard-specific: would involve assessing
resilience of various elements within the
network/route, and comparing with a
desired level based on risk.
2 All-hazards: would involve assessing
resilience of various elements within the
network/route to ‘all-hazards’, and
comparing with a desired level based on
criticality of the network/route.
1 This would enable actions and
interventions to be prioritised across
the broader transport system in
relation to specific identified hazards.
2 This would enable actions and
interventions to be prioritised across
the broader transport system in
relation to ‘all-hazards’.
Regional* 1 Hazard-specific: would involve assessing
resilience of various critical elements
within the region, and developing a
stand-alone score.
2 All-hazards: would involve assessing
resilience of various critical elements
within the region to ‘all-hazards’, and
developing a stand-alone score.
1 This would enable regions to be
compared, and actions and
interventions to be prioritised across
regions in relation to specific identified
hazards.
2 This would enable regions to be
compared, and actions and
interventions to be prioritised across
regions in relation to ‘all hazards’.
(A national assessment could be generated
by aggregating regional scores that could
then be utilised by the NIU.)
*An alternative approach to assessment at a regional level would be to undertake individual asset or network
assessments, and aggregate individual resilience scores into a regional score. This would require more detail, and it is
suggested that the approach above is implemented in the first instance.
7.1 Summary
The resilience measurement framework could be applied as a standalone assessment; however, in practice
the framework should be implemented either via an ‘all-hazards’ approach or a ‘hazard-specific’ approach
– either at an asset, network or regional scale.
The ‘all-hazards’ approach would involve an initial criticality assessment.
The ‘hazard-specific’ approach would involve a risk assessment and a more detailed understanding of
potential hazards and failure possibilities.
It is important to emphasise here that this is a resilience assessment tool and not a risk assessment tool,
although risk does form an important part of implementation.
Measuring the resilience of transport infrastructure
48
8 Example assessments
This section covers two high level examples through which the measurement framework is illustrated. The
examples are fictitious, but serve to illustrate the application of the framework.
8.1 Regional all-hazard assessment
Table 8.1 summarises the assessment approach. The detailed questions for the assessment are included
within appendix B.
Table 8.1 Example all-hazard assessment
Assessment context
and approach:
Regional, all hazard, pre-event.
Assessment to be undertaken initially as a stand-alone assessment.
Assessment
example:
Regional event (significant physical damage to transport infrastructure, coupled with severe
disruptions to other lifeline services such as electricity, water and telecommunications).
[An organisation that has experienced a few major disasters some time ago and has some
resilience responses in place but is just starting to re-invigorate its resilience preparation
and integration].
Technical resilience
assessment:
Robustness: Robustness is assessed via a series of measures across the categories of
structural, procedural and interdependencies. An example assessment is given below. Note:
all categories are weighted equally.
Structural: Across the five measures, the average score is 2.8, which is ‘moderate’.
[Rationale: maintenance and renewal of assets is acceptable, however most critical assets
(such as bridges) are not up to current design code levels, as they were built in the 1960’s].
Procedural: Across the one measure, the average score is 2.0, which is ‘moderate’.
[Rationale: design codes and guidelines do not adequately address resilience issues].
Interdependencies: Across the two measures, the average score is 2.0, which is ‘moderate’.
[Rationale: planning for resilience by interdependent utilities is less than adequate].
Overall robustness score of 2.3 (moderate).
Redundancy: Redundancy is assessed via a series of measures across the categories of
structural, procedural and interdependencies. An example is given below. Note: all
categories are weighted equally.
Structural: Across the four measures, the average score is 2.0, which is ‘moderate’.
[Rationale: indicates that availability and capacity of alternative routes and modes is less
than adequate].
Procedural: Across the one measure, the average score is 2.0, which is ‘moderate’.
[Rationale: indicates planning for diversions to alternate routes is less than adequate].
Interdependencies: Across the two measures, the average score is 2.0, which is ‘moderate’.
[Rationale: supplier awareness of redundancy issues, and implementation of improvements
is less than adequate].
Overall redundancy score of 2.0 (moderate).
Safe-to-fail: Safe-to-fail is assessed via two single measures. An example is given below.
Note: all categories are weighted equally.
Structural: Across this measure, the score is 2.0, which is ‘moderate’. [Rationale: indicates
safe-to-fail design and planning is less than adequate].
Procedural: Across this measure, the score is 2.0, which is ‘moderate’. [Rationale: indicates
safe-to-fail design and planning is less than adequate].
Overall safe-to-fail score of 2.0 (moderate).
Score 4 3 2 1
Score 4 3 2 1
Score 4 3 2 1
8 Example assessments
49
Organisational
resilience
assessment:
Change readiness: Change readiness is assessed across 11 categories as summarised in
table 6.2. A range of measures are assessed for each category – as summarised below:
Note: all categories are weighted equally.
Communication and warning 1.5 (note poor communication and warning)
Information and technology 2.0
Insurance 3.0 (good insurance cover)
Internal resources 2.3
Planning strategies 2.1
Clear recovery priorities 2.5
Proactive posture 2.0
Drills and response exercises 3.2 (note well prepared)
Funding 1.7 (note poor funding)
Situation awareness (sensing) 1.5 (note poor ability to sense new hazards)
Learning 2.5
Overall change readiness score of 2.7 (high).
Networks: Networks are assessed across three categories as summarised in table 6.2. A
range of measures are assessed for each category – as summarised below: Note: all
categories are weighted equally.
Breaking silos 3.0 (good score)
Leveraging knowledge (internal and external) 1.5 (poor score)
Effective partnerships (external) 2. 1
Overall networks score of 2.2 (moderate).
Leadership and culture: Leadership and culture is assessed across four categories as
summarised in table 6.2. A range of measures are assessed for each category – as
summarised below: Note: all categories are weighted equally.
Leadership 3.0 (good score)
Staff engagement and involvement 3.0 (good score)
Decision making authority 3.0 (good score)
Innovation and creativity 2.0
Overall leadership score of 2.8 (high).
Summary As a result of the assessment the following aggregate scores are produced:
Technical: 2.1, Organisational: 2.6
Overall resilience score: 2.3
While both scores are near the middle of the range, this indicates the priority may be to
invest in the technical response. However, there are significant areas for improvement
across both technical and organisational.
While this is a fictitious example, it clearly illustrates the usefulness in being able to:
1 Interrogate individual scores to explain/understand the outcomes
2 Clearly communicate areas for improvement
3 Generate an overall resilience score to give a broad understanding.
8.2 Asset, hazard-specific assessment
In order to illustrate an example relevant to a particular asset, and for a given hazard type, it is useful to
expand on the above example. We have not presented an entirely new assessment, as this would give little
value. We have, however discussed what the additional steps and considerations would be in this situation.
Score 4 3 2 1
Score 4 3 2 1
Score 4 3 2 1
Score 4 3 2 1
Measuring the resilience of transport infrastructure
50
Table 8.2 Example hazard-specific assessment
Assessment context
and approach
Asset, hazard-specific, pre event.
Assessment to be undertaken as per figure 7.2, and consisting of an initial criticality and
risk assessment to determine ‘desired’ level of resilience, followed by resilience
assessment.
Assessment example Major connecting road to port, determined as a highly critical asset. Hazard to assess is
flooding.
Risk assessment Risk implication of flooding includes:
• damage to pavement or other assets (eg embankments, structures, drainage assets
etc)
• transport delays of goods from facilities to the export port, as well as delays to
general traffic
• short-term loss of port access leading to increased service disruptions due to
increased maintenance regimes
• back-up of goods that cannot leave or access the port generating a financial burden
on importers and exporters
• increased coastal flooding from extreme rainfall events and sea level rise as water
cannot drain into the sea due to outfall pipes being below sea level.
Risk assessment as per the Transport Agency risk tool generates an ‘extreme risk’ score
(requires urgent attention). Therefore a ‘very high’ level of resilience is required.
Technical resilience
assessment
A similar assessment would be undertaken as per the previous example; however,
questions would relate to the specific asset in question, and the specific hazard (flooding)
being assessed. No further detail is provided.
Organisational
resilience assessment
A similar assessment would be undertaken as per the previous example; however,
questions would relate to the organisation’s ability to respond to the specific hazard
(flooding) being assessed, and the specific type and location of the asset. No further
detail is provided.
Summary As a result of the assessment it is assumed an identical score is produced as follows:
Overall resilience score: 2.3
The desired ‘very high’ level of resilience is 4.0, and therefore interventions are required
to improve the score, both in a technical and organisational sense.
As discussed above, interrogation of the individual scores will identify where
improvements can be made.
Score 4 3 2 1
9 Conclusions and future work
51
9 Conclusions and recommendations
9.1 Conclusions
The Transport Agency has a key interest in ensuring that transport infrastructure assets and services
function continually and safely. This interest has led to a specific focus on the concept of resilience and
how this can be defined, measured and improved across the transport system.
In a transport context, societies rely on transportation networks for their activities. The ability of the
transport system to function during adverse conditions and quickly recover to acceptable levels of service
after an event is fundamental to the wellbeing of communities.
The framework developed through this study gives effect to the guiding principle of resilience within the
NIP and links to the NIP resilience attributes developed by the Treasury. It is applicable to the broad land
transport system (road and rail), and allows assessments at various scales (asset/network/region). The
assessment can be applied as both a non-specific ‘all-hazards’ approach or a ‘hazard-specific’ approach.
A key difference between these approaches is the incorporation of a risk assessment component. An all-
hazards approach accounts for the unpredictability of future extreme events and emergent hazards. As
these events are inherently unknowable, a likelihood of occurrence cannot be estimated, and as such, a
risk assessment is not applicable. However, if specific hazards are well known and are required to be
assessed, then a risk-based assessment can be undertaken.
A broadly qualitative framework was developed, which provides the user with a flexible, simple and
practical tool to understand resilience of the transport system and as a result, prioritise investment
decisions. The framework utilises the following dimensions and principles, developed from a variety of
sources, and which encapsulate the key considerations both from a technical and, importantly, an
organisational point of view.
Dimension Principle
Technical Robustness, redundancy, safe-to-fail
Organisational Change readiness, networks, leadership and culture
The assessment process consists of a range of questions within each principle, and to which the user can
assign scores. Each individual score can be weighted at the discretion of the user, and scores aggregated
to the principle or dimension level if required. In addition, if applied at a regional level, the overall
regional scores could be further summarised to give a picture of national resilience for use within NIU
reporting.
Due to project constraints, detailed real-scenario testing of the framework was not undertaken (instead, a
hypothetical example assessment was provided to illustrate the application of the framework). Specific
operator knowledge of assets and the relevant organisations would be required to meaningfully undertake
an assessment and it is recommended that this be considered as a subsequent stage.
9.2 Recommendations
A number of other improvements are suggested that may enhance resilience understanding and aid in the
implementation of the framework. These are:
Measuring the resilience of transport infrastructure
52
• Identify ways to improve understanding of critical infrastructure and factors which may determine
criticality - from both an economic and societal point of view. These may include factors such as:
providing access to critical infrastructure nodes (eg control centres or substations), access to critical
community facilities (eg hospitals), or sections of road that have no alternative routes.
• Undertake further economic and engineering research to better understand and quantify a suitable
level of investment in technical (structural) resilience. This is generally where significant capital
expenditure is required, and is difficult to justify when funding is limited. A recent Australian study
Building our nation’s resilience to natural disasters (Deloitte 2013) compared investment in pre-
disaster resilience with post-disaster expenditure on relief and recovery – through a number of case
studies. General findings showed that for a vast majority of pre-disaster resilience initiatives, the
benefit–cost ratio was favourable, highlighting that the policy response to building resilience to
natural disasters must focus on prevention. Similar work is required in a New Zealand context.
• Improve understanding of linkages between resilience and sustainability. To date, conversations
around infrastructure resilience have occurred largely in isolation of those which occur around
sustainability. However, it is clear that many resilience measures are also measures that may be
implemented to improve sustainability (such as green infrastructure, decentralised systems). Bringing
the two fields of study together may lead to improved outcomes for both and should be explored
further in both an academic and practical sense.
10 References
53
10 References
AECOM, Arcadis, US Department of Transportation, Metropolitan Transportation Commission, Caltrans,
Bay Conservation and Development Commission (2011) Adapting to rising tides: transportation
vulnerability and risk assessment pilot project. Briefing book, November 2011. Accessed 23 November
2013. www.mtc.ca.gov/planning/climate/Rising_Tides_Briefing_Book.pdf
Allenby, B and J Fink (2005) Toward inherently secure and resilient societies. Science 309, no.5737: 1034–
1036.
Anderies JM, AA Rodriguez, MA Janssen and O Cifdaloz (2007) Panaceas, uncertainty, and the robust
control framework in sustainability science. In Proceedings of the National Academy of Sciences of the
United States of America 104, no.39: 15194–15199.
Auckland Engineering Lifelines Project (2012) Assessing Auckland’s infrastructure vulnerability to natural
and man-made hazards and developing measures to reduce our region’s vulnerability. Auckland
Engineering Lifelines Group report, version 1.0.
Australian Greenhouse Office (AGO) (2006) Climate change impacts and risk management. A guide for
business and government. Canberra: Department of the Environment and Heritage, Australian
Greenhouse Office.
Beatley, T (1998) The vision of sustainable communities. Chapter 8 in Cooperating with nature. R Burby
(Ed). Washington, DC: National Academy Press, Joseph Henry Press.
Berger, A, C Kousky and R Zeckhauser (2008) Obstacles to clear thinking about natural disasters: five
lessons for policy. Pp73–94 in Risking house and home: disasters, cities, public policy. JM Quigley and
LA Rosenthal (Eds). Berkeley, CA: Berkeley Public Policy Press.
Brabhaharan, P (2006) Recent advances in improving the resilience of road networks. New Zealand Society
of Earthquake Engineering Conference 2006.
Brabhaharan, P, MJ Fleming and R Lynch (2001) Natural hazard risk management for road networks. Part I:
Risk management strategies. Transfund New Zealand research report 217. 75pp.
Brabhaharan, P, LM Wiles and S Frietag (2006) Natural hazard road risk management. Part III: Performance
criteria. Land Transport New Zealand research report 296. 126pp.
Brenkert, A and E Malone (2004) Modeling vulnerability and resilience to climate change: a case study of
India and Indian States. Climatic Change 72: 57–102.
Brundson, D and E Dalziell (2005) Making Organisations Resilient: Understanding the Reality of the
Challenge. Pp27–34 in Resilient Infrastructure Conference Handbook. Rotorua 8–9 August 2005.
Bruneau, M, S Chang, R Eguchi, G Lee, T O’Rourke, A Reinhorn, M Shinozuka, K Tierney, W Wallace and D
von Winterfelt (2003) A framework to quantitatively assess and enhance the seismic resilience of
communities. EERI Spectra Journal 19, no.4: 733–752.
Christchurch Engineering Lifelines Group (1997) Risks and realities. A multidisciplinary approach to the
vulnerability of lifelines to natural hazards. Christchurch: University of Canterbury.
Comfort, L (1999) Shared risk: complex systems in seismic response. New York: Pergamon.
Measuring the resilience of transport infrastructure
54
Commonwealth of Australia (2011) Organisational resilience. Position paper for critical infrastructure.
Accessed 24 November 2013.
www.emergency.qld.gov.au/publications/pdf/Organisational_Resilience.pdf
Croope, S (2010) Managing critical civil infrastructure systems: improving resilience to disasters. PhD
dissertation, University of Delaware.
Dantas, A and S Giovinazzi (2010) Benchmarking the readiness of road controlling authorities to meet
their obligations under the Civil Defence and Emergency Management (CDEM) Act 2002. NZ Transport
Agency research report 409. 90pp.
Deloitte (2013) Building our nation’s resilience to natural disasters. Report prepared by Deloitte Access
Economics for the Australian Business Roundtable for Disaster Resilience and Safer Communities.
Engle, NL (2011) Adaptive capacity and its assessment. Global Environmental Change 21: 647–656.
Folke C, S Carpenter, T Elmqvist, L Gunderson, CS Holling, B Walker, J Bengtsson, F Berkes, J Colding, K
Danell, M Falkenmark, L Gordon, R Kasperson, N Kautsky, A Kinzig, S Levin, K-G Mäler, F Moberg, L
Ohlsson, P Olsson, E Ostrom, W Reid, J Rockström, H Savenije and U Svedin (2002) Resilience and
sustainable fevelopment: building adaptive capacity in a world of transformations. ICSU Series on
Science for Sustainable Development, no.3.
Foster, HD (1997) The Ozymandias principles: thirty-one strategies for surviving change. Victoria, BC: UBC
Press.
Gallopin, G (2007) Linkages between vulnerability, resilience and adaptive capacity. Formal Approach to
Vulnerability Workshop, Potsdam Institute for Climate Impact Research. Potsdam, 13–14 September
2007.
Gardiner, L, D Firestone, G Waibl, N Mistal, K Van Reenan, D Hynes, J Smart, J Byfield, S Oldfield, S Allan, B
Kouvelis, A Tait and A Clark (2008). Climate change effects on the land transport network. Volume one:
literature review and gap analysis. NZ Transport Agency research report 378. 226 pp.
Godschalk, DR (2002) Urban hazard mitigation: creating resilient cities. Urban Hazards Forum, John Jay
College, City University of New York, January 2002.
Godschalk, DR, T Beatley, P Berke, DJ Brower and EJ Kaiser (1999) Natural hazard mitigation: recasting
disaster policy and planning. Washington, DC: Island Press.
Gordon, M and S Matheson (2008) Engineering lifelines and transport – should New Zealand be doing it
better? Part one. Phase 1: Situation scan. Phase 2: New Zealand risk exposure. NZ Transport Agency
research report 355A. 94pp.
Grubinger, V (2012) Resilience and sustainability in the food system. Accessed February 2013.http://learn.uvm.edu/foodsystemsblog/2012/10/22/resilience-and-sustainability-in-the-food-system/
Hamad, K and S Kikuchi (2002) Developing a measure of traffic congestion: fuzzy inference approach.
Transportation research record no.1802: 77–85.
Heaslip, K, W Louisell and J Collura (2009) A methodology to evaluate transportation resiliency for regional
network. 88th Transportation Research Board Annual Meeting. Washington DC.
Heaslip, K, W Louisell, J Collura and N Urena Serulle (2010) An evaluation of network transportation
siliency for disasters and other events. 89th Annual Meeting of the Transportation Research Board.
Washington DC.
10 References
55
Hillson, D (2013) Accessed May 2013.http://programme-recruitment.com/dr-david-hillson-s-article-
archive.../opportunities-are-the-same-as-threats..
Hollnagel, E (2011) Understanding accidents, or how (not) to learn from the past. Accessed May 2013.
www.functionalresonance.com/FRAM-1_understanding_accidents.pdf
Ladbrook, W (2012) Infrastructure resilience. What does it mean for my agency/organisation? Version 1.0.
Lee, A, J Vargo and E Seville (2013) Developing a tool to measure and compare organisations’ resilience.
Natural Hazards Review 14, no.1: 29–41.
Levina, E and D Tirpak (2006) Adaptation to climate change: key terms. Report for the Organisation for
Economic Co-operation and Development and International Energy Agency.
McRoberts, N (2010) Sustainability and resilience demystified. Accessed February 2013,
www.knowledgescotland.org/briefings.php?id=116
Madni, AM and S Jackson (2009) Towards a conceptual framework for resilience engineering. Systems
Journal, IEEE 3, no.2: 181–191.
Maguire, B and S Cartwright (2008) Assessing a community’s capacity to manage change: a resilience
approach to social assessment. Report for the Australian Government Bureau of Rural Sciences.
Malone, EL (2009) Vulnerability and resilience in the face of climate change: current research and needs
for population information. Report prepared by Batelle Memorial Institute. Washington: DC: Population
Action International.
Manyena, S, G O’Brien, P O’Keefe and J Rose (2011) Disaster resilience: a bounce back or bounce forward
ability? Local Environment 16, no.5: 417–424.
Mayunga, J (2007) Understanding and applying the concept of community disaster resilience: a capital-
based approach. Accessed 25 November 2013. www.ehs.unu.edu/file/get/3761
Mello, L (2005) Fat-tailed distributions in catastrophe prediction. CoRR abs/cs/0512022. Accessed 25
November 2013.http://arxiv.org/ftp/cs/papers/0512/0512022.pdf
Mileti, DS (1999) Disaster by design: a reassessment of natural hazards in the United States. Washington
DC: Joseph Henry Press.
Mostashari, A, M Omer and R Nilchiani (2009) Assessing resilience in a regional road based transportation
network. Hoboken, NJ: Stevens Institute of Technology.
Murray-Tuite, P (2006) A comparison of transportation network resilience under simulated system
optimum and user equilibrium conditions. In Proceedings of the 2006 Winter Simulation Conference,
Monterey, CA.
Ministry for the Environment (2008) Climate change effects and impacts assessment. A guidance manual
for local government in New Zealand. 2nd ed. Wellington: Ministry for the Environment.
Ministry of Civil Defence & Emergency Management (CDEM) (2005) Recovery management. Director’s
guidelines for CDEM Groups [DGL 4/05].
National Infrastructure Advisory Council (NIAC) (2010) A framework for establishing critical infrastructure
resilience goals. Final report and recommendations by the council. Washington DC.
National Infrastructure Unit (NIU) (2011) National infrastructure plan 2011. Wellington: National
Infrastructure Unit, The Treasury.
Measuring the resilience of transport infrastructure
56
National Infrastructure Unit (NIU) (2012) National infrastructure plan – resilience. Stakeholder memo from
Roger Fairclough (NIU). Accessed 25 November 2013.
www.infrastructure.govt.nz/plan/2011implementation/nip-resil-28jun12.pdf
New Zealand Asset Management Support (NAMS) (2011) International infrastructure management manual.
Wellington: NAMS Group.
New Zealand Government (2012) Infrastructure 2012. National state of infrastructure report. Wellington:
National Infrastructure Advisory Board and National Infrastructure Unit, The Treasury.
O’Rourke, TD (2007) Critical infrastructure, interdependencies and resilience. The Bridge 37, no.1.
Park, J, TP Seager, PSC Rao, M Convertino and I Linkov (2013) Integrating risk and resilience approaches to
catastrophe management in engineering system. Risk Analysis 33, no.3: 356–367.
PwC Ltd and GHD Ltd (2012) Implementing the national infrastructure plan in the water industry – a pilot
study. Accessed June 2013. www.waternz.org.nz/Category?Action=View&Category_id=98
Resilient Organisations (2012) What is organisational resilience? Accessed 15 February 2013.
www.resorgs.org.nz/Content/what-is-organisational-resilience.html
Saunders, C, W Kaye-Blake, R Campbell, P Dalziel and K Kolandi (2010) Capital based sustainability
indicators as a possible way for measuring agricultural sustainability, ARGOS research report 10/02.
Seville, E (2009) Resilience: great concept but what does it mean for organisations? Tephra 22: 9–15.
Community resilience special issue.
Seville, E and J Metcalfe (2005) Developing a hazard risk assessment framework for the New Zealand state
highway network. Land Transport NZ research report 276. 80pp.
Seville, E, D Brunsdon, A Dantas, J Le Masurier, S Wilkinson and J Vargo (2006) Building organisational
resilience: a summary of key research findings. Resilient Organisations research report 2006/04.
Snowdon, D (2006) Safe-fail or fail-safe. Accessed June 2013.http://cognitive-
edge.com/blog/entry/4501/safe-fail-or-fail-safe/
Snowdon, D (2011) Risk and resilience. Accessed June 2013. www.youtube.com/watch?v=2Hhu0ihG3kY
Solomon, S, D Qin, M Manning, Z Chen, M Marquis, KB Averyt, M Tignor and HL Miller (Eds) (2007) Climate
change 2007: the physical science basis. Contribution of Working Group I to the Fourth Assessment
Report of the Intergovernmental Panel on Climate Change. Cambridge, UK and New York, USA:
Cambridge University Press: 996pp.
Stockholm Resilience Centre (2007) What is resilience? Accessed February 2013.
www.stockholmresilience.org/21/research/what-is-resilience.html
Taleb, N (2010) The black swan: the impact of the highly improbable. 2nd ed. New York: Random House.
Treasury (2011a) Better capital planning and decision making. Wellington: The Treasury.
Treasury (2011b) Working towards higher living standards for New Zealanders. Wellington: The Treasury.
Treasury (2012) Better business cases. Wellington: The Treasury.
United Nations Disaster Relief Co-ordinator (UNDRO) (1980) Natural disasters and vulnerability analysis.
Report of Experts Group, meeting of 9–12 July 1979. Geneva: UNDRO.
United Nations International Strategy for Disaster Reduction (UNISDR) (2004) Living With risk. A global
review of disaster reduction initiatives. Geneva: UNISDR.
10 References
57
United States Department of Homeland Security (USDHS) (2009a) Concept development: an operational
framework for resilience. Prepared for Department of Homeland Security Science and Technology
Directorate.
United States Department of Homeland Security (USDHS) (2009b) National infrastructure protection plan.
Partnering to enhance protection and resiliency.
Urena Serulle (2010) Transportation network resiliency: a fuzzy systems approach. Accessed 29 November
2013.http://digitalcommons.usu.edu/etd/769/
URS (2005) Critical land transport infrastructure risk management review. Report prepared for Ministry of
Transport, Wellington.
Victoria Transport Policy Institute (VTPI) (2010) Evaluating transport resilience. Evaluating the
transportation system’s ability to accommodate diverse, variable and unexpected demands with
minimal risk. Accessed February 2013. www.vtpi.org/tdm/tdm88.htm
Zolli, A (2012) Goodbye sustainability, hello resilience. Accessed September 2013.http://andrewzolli.com/from-sustainability-to-resilience/
Measuring the resilience of transport infrastructure
58
Appendix A: NZ Transport Agency risk tool
Table A.1 Consequence rating
The outcome to the organisation from the risk event if it is not mitigated/treated more than it is currently
Minimal Minor Moderate Major Substantial
Category Sub-category 1 10 40 70 100
Financial
(operational/
capital funding)
–
Minor variance able to be
absorbed within budget
$100,000 to 25% capacity of failed mode(s)
N/A - Provide no score
N/A
Back up
inventories
and
equipment
Region Availability of back up
equipment and replacement
inventories available to
respond to an event
Existence of plan/requirements for back
up equipment relevant to different
hazards and critical assets.
Availability/readiness of back up
equipment for deployment
4 – Requirements are well specified for different assets.
Equipment is available and ready
3 – Requirements are well specified, however, not enacted
2 – Ad hoc approach
1 – No plan/requirements
2.0
Procedural Diversion and
communicatio
n plans
Region Diversion plans to alternate
routes
Existence of robust, tested plans to
establish diversions to alternate routes
when failure of critical link occurs
4 – Plans are well specified for different assets. Systems are
available, tested and ready
3 – Plans are well specified, however, not enacted
2 – Ad hoc approach
1 – No plan/requirements
2.0 2.0 33.33% 66.66
Measuring the resilience of transport infrastructure
64
REDUNDANCY continued Weighted redundancy score 2.0
Category 1 Category 2 Filter: asset or
regional
(network)
assessment
Item# Item measured Measurement Measurement scale Individual
score
Category
average
Weighting
(%)
Weighted
score
Note/justification
Inter-
dependencies
Supplier
utility
redundancy
Region Awareness of redundancy
issues (vulnerabilities) in
supplier utilities. Do
suppliers have sufficient
system redundancy,
resources, backup,
materials, fuel etc to provide
sufficient redundancy
Supplier staff and Transport Agency staff
aware of redundancy issues within
suppliers utilities (power, telecom, other)
4 – Good awareness and have been followed up
3 – Some awareness
2 – Minor awareness
1 – No awareness 2.0
2.0 33.33% 66.66
Supplier
utility
procedures
Region Suppliers have implemented
procedures to
measure/improve
redundancy
Evidence that suppliers have
implemented procedures and
improvements and that these are
effective
4 – Suppliers have developed and implemented procedures
and there is strong dialogue
3 – Initial dialogue and plans are being prepared
2 – Initial dialogue
1 – No action or evidence
2.0
SAFE-TO-FAIL Weighted safe-to-fail score 2.0
Category 1 Category 2 Item# Item measured Measurement Measurement scale Individual
score
Category
average
Weighting
(%)
Weighted
score
Note/justification
Structural
Design Region Have safe-to-fail design
approaches been considered
in conjunction with
robustness and redundancy
design approaches (where
considered relevant) for
existing assets?
Evidence that safe-to-fail is considered
across critical asset/route designs in the
region and when planning for asset
renewal and upgrades to improve
resilience
4 – Design documentation shows consideration or
incorporation of safe-to-fail approaches for >80% of critical
assets where relevant.
3 – Design documentation shows consideration or
incorporation of safe-to-fail approaches for >50%, 50%, 75% reached
2 – > 40-75% reached
1 –