Evaluating Transportation Resilience
Evaluating The Transportation System’s Ability To Accommodate Diverse, Variable and Unexpected Demands With Minimal Risk
Victoria Transport Policy Institute
Updated 6 September 2019
This chapter explores the concept of resilience and the role that TDM strategies can play in creating a more resilient transportation system.
Resilience (also called reliability and risk management) refers to a system’s ability to accommodate variable and unexpected conditions without catastrophic failure, or “the capacity to absorb shocks gracefully” (Foster, 1993). Security refers to freedom from danger or fear, which is an important goal of resilience. These concepts have many implications for planning in general, and transportation planning in particular (Berdica, 2002; Husdal, 2005). Resilience can be evaluated at various levels.
· At an individual level it means that people have Transportation Options needed to satisfy their transportation needs even under unusual and unexpected conditions, such as when their automobile breaks down, if they become physically disabled, or their income decreases.
· At a community level it means that a transportation system can safely and efficiently accommodate unusual conditions, including construction projects, Emergencies, Special Events, and gathering; and that the transport system can provide Basic Accessibility to people with special needs, including people with, low incomes, disabilities, or who do not speak the local language.
· At a design level it means that facilities can withstand extreme demands and unexpected conditions, including major equipment failures, disasters and new technologies.
· At an economic level, it means that transportation services can be provided if a particular resource, such as petroleum, becomes scarce and expensive.
· At a strategic planning level it mean that a transportation system can meet long-term economic, social and environmental goals under a wide range of unpredictable future conditions (Sustainable Development).
Resilience reflects uncertainty, our inability to know what combination of conditions will occur in the future. If the future were predictable, Resilience would lose its importance: individuals and communities would simply need to plan for a single set of conditions. But since the future is unpredictable, it is necessary to plan for a wide range of possible conditions, including some that may be unlikely but which could result in significant harm if they are not anticipated.
The value of Resilience explains why people and communities are often willing to support transportation options and services that they currently do not use, in order to have them available if needed in the future, just as ship passengers value having life boats even when they are not being “used”. Economists call this “option value” (ECONorthwest and PBQD, 2002).
Resilience tends to increase if a system has diversity, redundancy, efficiency, autonomy and strength in its critical components. This allows the system to continue functioning if a link is broken, if a particular resource becomes scarce, if a particular decision-maker is unavailable, etc. It allows the system to accommodate a wide range of user needs and conditions.
Mobility can be an important strategy for increasing Resilience. Mobility permits movement away from adverse conditions or towards areas of greater need. For example, a common response to Disasters such as hurricanes and wars is to evacuate people from risky areas, and after such events occur there is often a need to bring in new resources to help with recovery efforts. An efficient transportation system is therefore an important part of a community’s overall resilience.
Resilience is affected by a system’s ability to collect and distribute critical information under extreme conditions. Resilience tends to increase if a system has effective ways to identify potential problems, communicate with affected people and organizations, and to Prioritize resources.
Resilience affected by a system’s ability to correct problems and perform repairs, even under extreme conditions. This means that critical components are self-correcting, repairable, redundant, autonomous (the failure of one component does not cause other components to fail), and fail-safe (i.e., if they fail they automatically shift to their most benign form). It means that decisions are incremental and reversible, so costs are minimized if a particular approach proves ineffective or dangerous.
Principles of Resilience (Foster, 1997)
Compatibility with diverse value systems.
Capacity to satisfy several goals.
Equitable distribution of benefits and costs.
Generous compensation for major losers.
Diversity of components.
Wide range of potential financial support.
High benefit-cost ratio
Early return on investments.
Equitable division of costs and benefits.
Minimal adverse impacts
Replenishable or extensive resource base.
Short lead time and rapid response to stimuli.
Open-ended life span.
Not site specific.
Fine grained and modular.
No esoteric components.
Unique skills unnecessary.
Early fault detection.
Many TDM strategies can improve transportation system Resilience by increasing transportation system diversity and flexibility, improving resource management, allowing resource Prioritization, improving communication, and by increasing the system’s overall efficiency.
Table 1 lists transportation system stresses, problems and risks, and TDM strategies that are particularly likely to address these problems and so increase system Resilience.
Table 1 Transportation Stresses and TDM Solutions
Individual or Household
Community or Region
Examples of transportation system stresses, problems and risks.
Temporary vehicle failure.
Loss of driving privileges.
Reduced income or increased financial obligations.
Physical disability or difficulty communicating.
Increased transportation responsibilities, such as an increased need to chauffeur children or visitors.
Increased stress from traffic and parking congestion.
Loss of an accustomed travel mode (such as a discontinued transit route).
Major sport or cultural event that attracts large crowds.
Emergencies and disasters: fire, earthquake, explosions, etc.
Closure of a major bridge, highway or rail line due to a crash, construction or other event.
Influx of visitor or refugees, particularly if they do not speak the local language or have other special needs.
Sudden change in the availability of vehicle fuel or other critical resource.
Increased travel demand due to growth in population or economic activities.
Strategies that can help mitigate these problems and increase transportation system resilience.
New Urbanism (connected road networks)
This table lists examples of stresses on the transportation system from individual’s and society’s perspectives, and TDM strategies that can help address those stresses.
There are many possible ways to evaluate transportation resilience (Money, et al. 2017). It can be evaluated based on a systems ability to provide its critical functions under variable, uncertain and extreme conditions. This involves identifying a system’s critical functions, its vulnerabilities, and ways to reduce vulnerabilities. Morlok and Chang (2004) discuss ways to quantify the ability of a transportation system to accommodate changing demands and traffic patterns. They describe two approaches, one of which holds traffic patterns constant, the second allows flexibility in traffic patterns, which reduces the amount of excess capacity needed at any point in the system to accommodate increased demand. This implies, for example, that the ability to shift travel routes, times, modes and destinations, through Transportation Demand Management, can be as important as increasing capacity to deal with sudden increases in peak demand. This type of analysis should involve more than simply contingency planning (considering “what would happen if…”) because it is not possible to predict every possible future condition. Below are specific steps in resilience planning. ECONorthwest and PBQD (2002) and Husdal (2003) describe methods for quantifying the value of an incremental change in resilience for incorporation into benefit/cost analysis.
The first step in this planning process is to define the extent of the system to be evaluated. For a transportation system this may include the transportation facilities and services in a particular jurisdiction or region, including those that connect outside of that area. All components of that system should be considered, including, for example, the pedestrian system, freight and package delivery systems, transportation for public services such as road maintenance and garbage collection, air travel systems, etc.
This involves identifying transportation activities and services are most valued to society. The list below is an example (Basic Accessibility).
This involves identifying various ways that a system’s components and requirements could fail or become inefficient. Below are some examples of potential problems to consider.
· A network link is broken, such as a blocked sidewalk, bridge or roadway.
· A service fails, such as a bus strike, or a motorist loses his or her ability to drive.
· A group of users has difficulty walking or is unable to speak the local language.
· A critical resource becomes scarce and expensive, such as a petroleum shortage.
· A common source of information fails or provides false information, such as an incorrect announcement of travel conditions by a radio station.
· A particular official, technician or repair crew is unavailable during a crisis.
· A disaster requires emergency transport of a large number of people, many who cannot drive, and some with medical problems.
· A disaster causes extreme traffic congestion on a particular roadway.
· A particular service is discontinued due to inadequate demand, such as local bus or freight delivery services.
The intent of this exercise is not to try to predict every possible problem that could occur, since it is impossible to know what combination of problems may occur. Rather, it is important to generalize the risks in order to find categories of vulnerabilities.
Find ways to reduce specific vulnerabilities, and incorporate Resilience principles into the planning and management of critical components of the transportation system. Below are examples of strategies that can increase Resilience.
· Increase transportation system Diversity. Insure that there are opportunities for people to walk, cycle, rideshare, carshare and travel by transit.
· Increase network redundancy and connectivity (e.g., the number of roads and transit routes in an area).
· Increase facility design and construction standards to withstand extreme conditions.
· Improve systems to identify potential problems, including physical damage, unusual demands and new risks.
· Improve the ability to communicate with transportation system users, including people with special needs, even under unusual conditions.
· Establish ways to Prioritize transportation system resources (road space, fuel, vehicle capacity) so it is available first to higher-value transportation activities.
Contingency Based (or Responsive) planning refers to the idea that the planning process must be able to change over time in response to future needs. This involves the following steps:
1. Identify objectives (general things that you want to achieve) and targets (specific things that you want to achieve).
2. Identify various strategies that can help achieve the objectives and targets. These can include both projects that increase capacity and demand management strategies.
3. Evaluate the costs and benefits of each strategy (including indirect impacts, if any), and rank them according to cost-effectiveness or benefit/cost ratios.
4. Implement the most cost-effective strategies as needed to achieve the stated targets.
5. After they are implemented, evaluate the programs and strategies with regard to various performance measures, to insure that they are effective.
6. Evaluate overall results with regard to targets to determine if and when additional strategies should be implemented.
Contingency-based planning addresses uncertainty by deploying solutions on an as-needed basis. For example, a transportation plan may identify 5 strategies to implement immediately, another 4 to implement in two years if stated targets are not achieved, and another 3 can be implemented further in the future if needed. This tends to be cost effective and flexible, because strategies are only deployed if they are needed, and additional strategies can be ready for quick implementation if unexpected changes create additional needs. This approach is ideal for medium and long-range transport and land use planning.
Resilience and security analyses are important for transportation planning. This can define design requirements (such as seismic standards for bridges) and service standards (such as transit service in lower-density areas). Many of the policies and practices that increase transportation system resilience are TDM strategies. Below are examples of ways to increase transportation system resilience and security.
· Value diversity, flexibility and redundancy. As much as possible try to develop a multi-modal transportation network. For example, if there are several possible ways to reduce traffic congestion problems, favor the solutions that help improve transportation system diversity.
· Avoid irreversible decisions. For example, maintain railroad rights-of-way for possible future and emergency uses.
· Use contingency-based planning that identifies a wide range of potential solutions and implements the most cost-effective strategies justified at each point in time, with additional strategies available for quick deployment if needed in the future.
· Design transportation facilities to withstand extreme conditions (earthquakes, storms, etc.).
· Incorporate security planning as part of transportation planning. Perform user surveys, safety audits and crime data reviews to identify and Address Security Risks. Find ways to communicate with transportation system users and include them in security planning.
· Include Emergency Response as part of all transportation planning (local, regional, national, transit, etc.). Consider disaster response as part of TDM planning, and TDM solutions as part of disaster planning. Consider the widest possible range of possible disasters and stresses on the transportation system, and consider the widest possible range of possible solutions.
· Create a well Connected transportation system network that provides multiple links to each destination.
· Encourage Transportation Options, particularly for transportation modes and services that help provide Basic Access. Support development of diverse and competing transportation services, such as Ridesharing, Telework, Delivery Services, etc.
· Insure that transport planning take into account people with special needs (physical disabilities, low incomes, inability to speak the local language, etc.). Develop plans to provide Basic Access to people with special needs, and under unusual conditions.
· Develop effective ways to maintain information and communication systems among transportation system managers, staff and users under normal and extreme conditions. Develop ways to warn travelers of problems and let travelers know their transportation options.
· Develop multiple, overlapping communication systems that will continue to function if one component fails.
· Develop ways to prioritize the allocation of transportation system resources. For example, design systems to allow emergency, public service and freight vehicles priority over general traffic during emergencies. Maintain contingency plans to allocate fuel and other resources in emergencies.
· Maintain ongoing transportation systems evaluation to provide early detection of possible problems and inefficiencies.
· Design critical components of the transportation system to be fail-safe, self-correcting, repairable, redundant and autonomous.
· Cross-train staff to perform critical management and repair services.
· Encourage efficient use of resources, including energy conservation and Accessible land use.
· Develop Comprehensive Planning that identifies the full impacts and vulnerabilities of a transport system.
TDM Planning and Comprehensive Planning describes ways to improve current transportation planning practices, including consideration of resilience. Address Security Concerns describes ways to identify and reduce perceived risks to transportation system users. Special Event and Emergency Response planning indicates ways to prepare for events that require special transportation responses. Transportation Options describes how to evaluate the quality of transportation choices that are available in a community.
Two hikers out in the woods encounter an angry bear. One stops to change from his boots into running shoes. “What are you doing? You can’t outrun a bear!” says his partner.
“I don’t need to outrun the bear. I just need to outrun you,” was the reply.
The magnitude 6.8 Northridge (Southern California) earthquake in January 17, 1994, severely damaged four freeways, parking structures and buildings. During the weeks after this event, total vehicle travel declined and public transit (particularly Metrolink rail transit) use increased significantly. Surveys indicate that about half of all Los Angeles residents, and 80% of commuters in the earthquake zone, changed their travel patterns, primarily changes in automobile route and travel time, and reducing discretionary travel. Many of these changes were temporary, but a significant number of commuters continued using transit services and surface streets after their former freeway routes were repaired. Researchers emphasized the importance of redundancy in the transportation system as part of disaster response.
This study defines and evaluates a transport system’s travel adaptive capacity to reduce fuel use in response to unexpected supply disruptions and price increases. Travel adaptive capacity is a measure of the resilience of transport activity systems to a reduction in fuel use for personal vehicle trips while not reducing participation in activities. It characterises the vulnerability to oil shocks of a particular urban area, organisation, socioeconomic or demographic group.
This study used an interactive travel adaptive capacity assessment survey (TACA survey), which collects habitual or ‘normal’ weekly travel activity patterns. Participants are asked to indicate up to three alternative modes for each trip. It asks ‘Do you have an alternative mode for this trip?’ The first alternative selection in the drop-down menu is ‘no alternative’. The study was used to estimate the price elasticity of vehicle travel with respect to significant fuel price increases. It found that many factors influence the availability of alternative modes for carrying out activities, particularly urban geography.
The study found that people in all demographic categories residing in all parts of the cities have the potential to adapt most of their current vehicle trips to other modes. Young people tend to have the highest adaptability. The largest share of adaptive potential is bus trips, but walking and biking feature nearly as prominently. Conversely, some people have no adaptability. While these people are found in all demographic categories, a higher proportion was found among the elderly and higher income participants. Participating in the activity without travelling, as in working from home or conducting a social visit by telephone, was selected for less than 1% of trips by all participants.
The fuel consumption associated with the alternative modes can be calculated from the travel distances associated with each individual’s adaptive potential and the vehicle information. The researchers recommend that the focus of transport policy should shift away from subsidies for measures like alternative fuels or electric vehicles, as the adaptive capacity for fuel reduction is larger than the capacity for uptake of new vehicles or making biofuel. Many people are currently aware of their alternatives, which is the first requirement for future behaviour change.
This is an information sheet provided by the U.S. Federal Transit Administration, based on experience with the September 11 terrorist attack on the World Trade Center.
Make a Plan
Work with your colleagues and counterparts in the police department, fire department, health department, public buildings department, and emergency management office to develop a plan that will be successful.
Review your plan regularly and update it when your system changes or new threats emerge
Plan for the worst. Determine what you will do if…
· Normal communication systems (television, web, radio, telecommunications) are not available.
· Electrical power is cut off.
· There are massive deaths or injuries.
· There are air-borne chemical or biological hazards.
Practice, Practice, Practice
Conduct regular emergency/disaster drills (not just fire drills!) to keep skills sharp and your plan up-to-date.
Build interagency relationships; every level of transit leadership should personally knows his/her counterparts in the agencies and organizations who will be responding to an emergency situation.
Some Things that Really Matter
Put the resources in place to execute your plan – people, equipment, facilities.
Identify alternative means of transportation for the transit-using public in case one or more of your primary modes is disabled.
Radio communication capability is essential because cell phones are not reliable during the emergencies; be sure you have multiple communication systems, in case one or more is inoperative.
Conduct criminal and credit background checks on every employee. Make sure every employee has a photo identification and require that it be displayed at all times.
Establish Command Central
Immediately set up a joint operations center so that your key responders can talk to each other face-to-face and make joint decisions.
Although it was not clear at the outset whether there was a terrible accident or a terrorist incident, the command center leadership made the decision to respond to the situation as a terrorist attack. As a result, the NYC transit authority immediately evacuated all trains, passengers and transit employees from the World Trade Center area – and there were no transit-related deaths or serious injuries and no equipment losses as a result of the collapsed building.
Be ready and willing to improvise; even a good plan can’t anticipate everything. NYC Transit made the decision to let everyone leave the city for free; this decision made the evacuation process quicker and built tremendous goodwill with the public.
Communicate with the Public
Use your website to communicate your service plans and availability with the public on a real-time basis.
NYC Transit has been getting 10 million hits a day, compared to a usual 200,000 hits, and updates its site every 2 hours even if no substantive changes to service have been made.
Work with local television and radio stations to get information about closings and alternative routes to the public
Restore Public Confidence
Increase law enforcement visibility; put a uniformed officer on every train, if possible, to reassure the public and deter potential threats.
Tell people – with brochures, ads, and announcements – how they can help enhance security.
Following the September 11, 2001 terrorism attacks in downtown New York City, Mayor Rudy Giuliani restricted private solo automobile travel on major bridges and roadways into the city center during morning rush hours. At the same time, transportation agencies established new Park & Ride facilities. Despite initial skepticism and some protests, the regulations were widely accepted and were considered effective. Transit travel from suburbs increased substantially, traffic delays declined and emergency, service and demolition vehicles were able to access the area of destruction for recovery and repair work.
APTA (2001), Checklists For Emergency Response Planning And System Security, American Public Transit Association (www.apta.com/services/safety/checklist.htm).
Katja Berdica (2002), “An Introduction to Road Vulnerability: What Has Been Done, Is Done and Should Be Done,” Transport Policy, Vol. 9. No. 2 (www.elsevier.com/locate/tranpol), April 2002, pp. 117-127.
Stephanie Chang and Nobuoto Nojima (2001), “Measuring Post-Disaster Transportation System Performance: The 1995 Kobe Earthquake in Comparative Perspective,” Transportation Research A, Vol. 35, No. 6 (www.elsevier.com/locate/tra), July 2001, pp. 475-494.
Thomas J. Cova and Steven Conger
(2004), “Transportation Hazards,” Handbook of Transportation Engineering,
(M. Kutz Editor) McGraw Hill (www.mcgraw-hill.com),
pp. 17.1-17.24; available at www.geog.utah.edu/~cova/cova-conger-teh.pdf.
J. Joseph Cronin, Roscoe Hightower and Michael Brady (2000), “Niche Market Strategies; The Role of Special Purpose Transportation Efforts in Attracting and Retaining Transit Users” Journal of Public Transportation, Vol. 3, No. 3 (www.cutr.eng.usf.edu), pp. 63-86.
Jago Dodson and Neil Sipe (2006), Shocking the Suburbs: Urban Location, Housing Debt and Oil Vulnerability in the Australian City, Research Paper 8, Urban Research Program, Griffith University (www98.griffith.edu.au); at www98.griffith.edu.au/dspace/bitstream/10072/12665/1/41353.pdf.
ECONorthwest and PBQD (2002), Estimating the Benefits and Costs of Public Transit Projects, TCRP Report 78, TRB (www.trb.org); available at http://gulliver.trb.org/publications/tcrp/tcrp78/index.htm.
Reid Ewing (1997), Transportation and Land Use Innovations; When You Can’t Build Your Way Out of Congestion, Planners Press (www.planning.com).
Harold Foster (1993), “Resilience Theory and System Evaluation,” in J.A. Wise, V.D. Hopkin V D and P. Stager (editors), Verification and Validation of Complex Systems: Human Factor Issues, NATO Advanced Science Institutes, Series F: Computer and Systems Sciences, Vol.110, Springer Verlag (New York), pp.35-60.
Harold Foster (1995), “Disaster Mitigation: The Role of Resilience,” in D. Etkin (editor) Proceedings of a Tri-lateral Workshop on Natural Hazards, Merrickville, Ontario, Canada, Feb 11-14, pp. 93-108.
FTA Safety and Security Website (http://transit-safety.volpe.dot.gov), by the U.S. Federal Transit Administration, provides information on transit safety and security issues, including disaster preparedness and response.
J.F. Hughes and K. Healy (2014), Measuring The Resilience Of Transport Infrastructure, Report 546, New Zealand Transport Agency (www.nzta.govt.nz); at www.nzta.govt.nz/resources/research/reports/546/docs/546.pdf.
Jan Husdal (2004), Why Reliability and Vulnerability Should be an Issue in Road Development Projects, first published in Samferdsel: Journal of the Norwegian Institute of Transport Economics (www.toi.no/samferdsel); at (www.husdal.com).
Genevieve Giuliano and Jacqueline Golog (1998), “Impacts of the Northridge Earthquake on Transit and Highway Use,” Journal of Transportation Statistics, Vol. 1, No. 2 (www.bts.gov), May 1998, pp. 1-20.
Erik Jenelius, Tom Petersen and Lars-Goran Mattsson (2006), “Importance and Exposure in Road Network Vulnerability Analysis,” Transportation Research A, Vol. 40, Issue 7 (www.elsevier.com/locate/tra), Aug. 2006, pp. 537-560.
Susan Krumdieck (2009), Pathways to meet the Challenge: Critical Change Projects, AEMS Laboratory, University of Canterbury (www.aemslab.org.nz); at www.resilientpathways.org.nz/resources/Susan_Krumdieck_Pathways.pdf.
Susan Krumdieck, Shannon Page and Montira Watcharasukarn (2012), Travel Adaptive Capacity Assessment For Particular Geographic, Demographic And Activity Cohorts, Research Report 486, NZ Transport Agency (www.nzta.govt.nz); at www.nzta.govt.nz/resources/research/reports/486/docs/486.pdf.
Harvey J. Miller (2003), “Transportation and Communication Lifeline Disruption,” in S. L. Cutter, D. B. Richardson and T. Wilbanks (eds.) The Geographic Dimensions of Terrorism, Routledge, pp. 145-152, available at www.geog.utah.edu/%7Ehmiller/papers/lifelines.pdf.
C. Money, et al. (2017), Establishing the Value of Resilience, Research Report 614 NZ Transport Agency (www.nzta.govt.nz), www.nzta.govt.nz/assets/resources/research-report-614/614-Establishing-the-value-of-resilience.pdf.
Edward K. Morlok and David J. Chang (2004), “Measuring Capacity Flexibility of a Transportation System,” Transportation Research A, Vol. 38, No. 6 (www.elsevier.com/locate/tra), July 2004, pp. 405-420.
Nancy W. Okasaki (2003), “Improving Transportation Response and Security Following a Disaster,” ITE Journal (www.ite.org), August 2003, pp. 30-32.
Resilience Alliance (www.resalliance.org) is a multidisciplinary research group that explores the dynamics of complex adaptive systems.
Nada D. Trout and Gerald L. Ullman (1997), “A Special Event Park-and-Ride Shuttle Bus Success Story,” ITE Journal (www.ite.org), December 1997, pp. 38-43.
Transportation Security Website (www4.trb.org/trb/homepage.nsf/web/security) provides information developed by the Transportation Research Board and National Academies of Science on transportation system security and protection.
USDOT (2005), Effects Of Catastrophic Events On Transportation System Management And Operations: New York City- September 11, U.S. Department of Transportation (www.itsdocs.fhwa.dot.gov//JPODOCS/REPTS_te/14129.htm).
This Encyclopedia is produced by the Victoria Transport Policy Institute to help improve understanding of Transportation Demand Management. It is an ongoing project. Please send us your comments and suggestions for improvement.
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