Investing in Transportation Resilience: A Framework for Informed Choices (2021) / Chapter Skim
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Pages 103-124
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From page 103... ...
103 Researchers have sought to develop direct measures of transportation system resilience, as discussed in the previous chapter. Recovery curves, which are conceptualized in the literature, define and describe resilience in terms of the loss of functionality and the time needed for restoration.
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104 INVESTING IN TRANSPORTATION RESILIENCE natural hazards today and over time, geographic settings, and infrastructure characteristics are vast and better measured by a portfolio of metrics. Interest in developing a salient set of metrics is understandable.
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DECISION SUPPORT FRAMEWORK 105 well as the disruptions to business activity that may result from the cancellation of travel altogether. The costs of disruption for seaport facilities were made up largely of the additional inventory costs of extending the supply chains and accommodating delays in bringing goods to market.
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From page 106... ...
106 INVESTING IN TRANSPORTATION RESILIENCE • Comprehensive so that it can be applied across modes, locations, time, and hazard types; • Capable of accounting for uncertainties about the future; • Practical to use, requiring data that are reasonable to obtain, and involving analyses that can be readily linked to more informed decision making; • Objective in the sense that quantitative metrics are used where available and reasonable, and qualitative assessments are informed by data or expert judgment and are transparent; • Broadly based by taking into account a locale's or region's quality of life and economy in addition to accounting for direct (and often more readily measurable) impacts on infrastructure owners and users; • Attentive to different time dimensions and cognizant of the resilience that is needed for immediate response and recovery from disaster as well as the resilience needed over the longer term for disruptions over the life cycle of assets, such as from the effects of climate change; and • Informed by the results of past investments, which can be helpful for understanding where resilience investments have paid off.
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DECISION SUPPORT FRAMEWORK 107 FIGURE 5-1 Components of the proposed decision support framework. Identifying Assets Transportation assets refer to the physical infrastructure, transportation workers, and institutional resources for all relevant transportation modes: road, railroad, maritime, inland waterways, aviation, public transit, bicycle and pedestrian facilities, and pipelines.4 To conduct resilience analysis, agencies need to have up-to-date information on their assets, including an asset's location, condition, vulnerability to damage, and history.
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108 INVESTING IN TRANSPORTATION RESILIENCE that are then certified by the Federal Highway Administration (FHWA) .5 Likewise, the Federal Transit Administration (FTA)
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DECISION SUPPORT FRAMEWORK 109 evaluate for vulnerability. Criticality metrics are typically a composite of several measures, not all of which may be represented in monetary terms.
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110 INVESTING IN TRANSPORTATION RESILIENCE Metropolitan Planning Organization, in its FHWA resilience pilot,9 used its travel demand model to assess criticality based on the regional significance of roads in the county. The analysis calculated an area-based criticality metric made up of the population and employment density of every Traffic Analysis Zone (TAZ)
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From page 111... ...
DECISION SUPPORT FRAMEWORK 111 Characterizing Natural Hazards and Their Likelihood Evaluation and quantification of the character and likelihood of natural hazards with the potential to affect the transportation system under analysis is a key element of the decision support framework. Hazard characterization is an input to the main resilience investment analysis and typically uses externally provided data.
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112 INVESTING IN TRANSPORTATION RESILIENCE precipitation data,10 the Federal Emergency Management Agency's flood maps,11 FHWA's Climate Model Intercomparison Project Climate Data Processing Tool,12 the Colorado Geological Service,13 OpenQuake14)
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DECISION SUPPORT FRAMEWORK 113 Evaluating the Consequences of Hazard Scenarios Consequences measure the economic and social costs resulting from the relevant hazard. Consequences are the values lost or disrupted.
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114 INVESTING IN TRANSPORTATION RESILIENCE the costs may be ongoing. Hazard-driven morbidity and mortality to those affected by the hazard are part of the consequences.
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DECISION SUPPORT FRAMEWORK 115 Estimating Risk In the proposed framework, risk is defined conceptually as follows: Risk = Hazard Likelihood × Vulnerability × Consequences where • Risk is the expected value of losses to the economy and society due to the disruption of transportation functionality caused by natural hazards, • Hazard likelihood describes probabilities of relevant natural hazards, • Vulnerability measures asset susceptibility to natural hazards, and • Consequences describe the value of functionality lost because of destruction of assets or service disruptions, including losses to asset owners, asset users, and communities. BOX 5-5 Examples of Metrics for Consequences Owner Consequences • Disruption response costs • Asset replacement costs • Asset repair costs • Cleanup costs • Loss of revenue • Liability for injuries or death • Loss of labor productivity User Consequences • Value of time lost to delay • Cost of added travel for detours and rerouting • Cost of foregone trips Community Consequences • Losses to local and regional economy -- Business or tourism sales lost -- Workdays lost -- Jobs lost • Environment damage • Isolation or loss of access • Other community impacts
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From page 116... ...
116 INVESTING IN TRANSPORTATION RESILIENCE Managing the risks resulting from disruptions due to natural hazards and climate change is a key objective for transportation agencies addressing resilience. This requires having an understanding of the risk associated with an asset or parts of the network due to the relevant hazards.
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From page 117... ...
DECISION SUPPORT FRAMEWORK 117 -- Adding redundancy -- for example, by adding new routes, improving alternative routes, adding or identifying alternative transportation modes, identifying alternative sources of supply of essential resources or services, or acquiring back-up power sources to support critical systems for multiple days (e.g., command and control centers, traffic signals, communication systems, rail crossing barriers, bridge lifts) ; and -- Relocating vulnerable facilities away from areas with high hazard exposure (e.g., rivers, coastal zones, unstable rock formations)
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From page 118... ...
118 INVESTING IN TRANSPORTATION RESILIENCE those costs that would be avoided because of the investment.15 This requires a detailed understanding of the asset or system being studied, which should come from the asset management plan, as well as a clear specification of the criterion hazard event or events. The difference between "with" and "without" the investment defines the benefit of that investment.
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DECISION SUPPORT FRAMEWORK 119 focusing on mitigation actions with some proven efficacy is advantageous. Still, design engineers should be able to address changes in structural performance under stress brought about by mitigation actions.
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120 INVESTING IN TRANSPORTATION RESILIENCE their property to be inadequate to match their perceived loss. Constructing additional highway capacity may increase highway usage, generating increased emissions of greenhouse gases and other pollutants.
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DECISION SUPPORT FRAMEWORK 121 or cost occurs. The higher the discount rate, the less those future benefits and costs count in present-value terms.
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122 INVESTING IN TRANSPORTATION RESILIENCE rate of 3.5% followed by a declining rate schedule for projects with longterm duration.18 BCA and the Investment Decision Formalizing system resilience concepts and analysis into transportation agency decision making can help decision makers make informed choices to manage the risks of disruptions caused by natural hazards and climate change stressors. The results of BCA can be critical to this process, and the framework proposed in this chapter to measure resilience benefits is conducive to the application of BCA.
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From page 123... ...
DECISION SUPPORT FRAMEWORK 123 CHAPTER SUMMARY This chapter's review of both practice and research suggests that more can be done to make the calculus of resilience a more systematic and deliberate part of transportation asset management and investment decision making. The review suggests that resilience should be measured and assessed using a multi-step, multi-hazard analytic framework.
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