Investing in Transportation Resilience: A Framework for Informed Choices (2021)

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7 The reinsurer Munich RE reported in January 2021 that in the preceding year, 6 of the world’s 10 most costly natural disasters occurred in the United States.1 The most destructive was Hurricane Laura ( Category 4 with winds of 240 km/h), which landed near Lake Charles in western Louisiana dur- ing August 2020. Its heavy winds, rain, tornadoes, and storm surge caused extensive flooding in the Gulf Coast states, with economic losses exceed- ing $13 billion. According to the Louisiana Depart ment of Transportation and Development, water damage from this storm eroded and undermined roadbeds; overtopped and damaged the mechanics of movable bridges, threatening marine travel; and spawned debris and high water that led to the closure of thousands of miles of highway, including the state’s longest and most heavily traveled Interstate bridge.2 Such large-scale natural disas- ters that wreak havoc on the condition and functioning of transporta- tion systems and other infrastructure are on the rise. During the 1980s, 1 Munich RE. 2021. “Record Hurricane Season and Major Wildfires—The Natural Disaster Figures for 2020.” https://www.munichre.com/en/company/media-relations/media- information- and-corporate-news/media-information/2021/2020-natural-disasters-balance.html. 2 LADOTD (Louisiana Department of Transportation and Development). 2020. “DOTD Request for Quick Release of Emergency Relief Funds to Assist with Hurricane Laura Damage Approved.” Press release, September 4. http://wwwapps.dotd.la.gov/administration/ announcements/Announcement.aspx?key=24327; Austin, N. 2020. “Most of I-10 Reopens in Louisiana Post-Hurricane Laura.” FreightWaves, August 28. https://www.freightwaves.com/ news/breaking-news-most-of-i-10-reopens-in-louisiana-post-hurricane-laura. 1 Introduction

8 INVESTING IN TRANSPORTATION RESILIENCE billion-dollar natural disasters, when adjusted for inflation, averaged 2.9 per year, but in 2020 alone the United States experienced more than 20.3 Beyond these disastrous events, climate change is bringing about slow but persistent changes in sea level and temperature and precipitation extremes that are intensifying storm damage and accelerating infrastructure deterioration.4 The country’s highways, ports, waterways, airports, railways, and pub- lic transit systems are vital to the economy and everyday lives of Americans. In the periods immediately before, during, and after natural disasters they are essential for evacuations, rescue, and access to critical supplies and services. Keeping their key components open and functioning as lifelines during the onset and in the midst of a natural disaster can be an impera- tive for emergency response, while rapid and safe restoration afterward can be foundational to communities and commerce in recovering and regain- ing a semblance of normalcy. The term for this capability to resist and rebound is “resilience,” and because transportation systems have critical local, regional, and national functions, the development and maintenance of this capability is a vital interest of governments across all jurisdictional levels and of the private sector. Because the responsibility of transportation agencies and industries is to invest to assure needed functionality, knowing how well that functionality will be preserved, replaced, and restored under conditions of stress from natural hazards and climate change is an inherent part of the investment calculus. Determining and measuring the resilience benefits conferred by investment choices, however, can be challenging because transportation assets are exposed to many kinds of natural hazards and hazard extremes over their long life spans, and they are part of larger systems that function on different spatial scales. What may seem to be a localized investment in a transportation asset could have broader implications on the functioning of the transportation system over a larger geographic region, including the system’s ability to compensate for other parts of the system that may become compromised by premature degradation or a disruptive event. A full and explicit accounting of resilience benefits would affect the decision calculus of many transportation investments. 3 The National Oceanic and Atmospheric Administration’s (NOAA’s) calculations of billion- dollar events are adjusted for inflation. See NOAA NCEI (National Centers for Environmen- tal Information). 2021. “U.S. Billion-Dollar Weather and Climate Disasters.” https://doi. org/10.25921/stkw-7w73. 4 Reidmiller, D.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, K.L.M. Lewis, T.K. Maycock, and B.C. Stewart, eds. 2018. Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II. Washington, DC: U.S. Global Change Research Program. https://doi.org/10.7930/NCA4.2018.

INTRODUCTION 9 Although most of the country’s public-sector transportation infrastruc- ture is owned and operated by state and local governments, the federal government has much at stake in ensuring that sufficient, effective, and timely investments are made to deliver a resilient national transportation system. The preservation and rapid restoration of the many important local and regional functions of transportation systems is in the public interest generally, and it is in the national interest to avoid disruptions that cascade across broader transportation and logistics networks, threatening economi- cally and socially critical supply chains. Accordingly, when transportation assets are damaged and do not operate efficiently, and system functionality is lost or seriously degraded in disasters, the federal government will often step in to provide emergency relief and recovery funding assistance. In recent years, the federal government has increasingly stressed the importance of enhancing the resilience of transportation systems when re- authorizing and amending both its regular federal aid programs and its post- disaster emergency relief programs. For example, the 2015 Fixing America’s Surface Transportation Act requires that statewide and metropolitan long- range highway and transit improvement plans consider projects and strate- gies to improve the resilience and reliability of the transportation system.5 For its Port Infrastructure Development grants, the Maritime Administra- tion encourages applicants to take into account climate change in project planning efforts and to include project components dedicated to mitigating or reducing impacts of climate change.6 In responding to the aftermath of Hurricane Sandy in 2012, Congress authorized the Federal Transit Admin- istration to set aside funding for communities impacted by the storm to compete for grants to cover public transit projects intended to reduce cur- rent and future vulnerabilities to disasters.7 The federal interest in building resilience into public infrastructure is also exemplified by the new Federal Emergency Management Agency (FEMA) Hazard Mitigation Assistance Grants program, which will award funds competitively for projects intended to increase a community’s resilience before a disaster affects an area.8 As resilience has become a more explicit and prominent goal for the allocation of transportation funding assistance, there is a growing interest 5 FAST Act, H.R.22, 114th Cong. (2015–2016). https://www.congress.gov/bill/114th- congress/house-bill/22/text. 6 U.S. DOT (U.S. Department of Transportation), Maritime Administration. 2021. “Fre- quently Asked Questions—Port Infrastructure Development Grants.” https://www.maritime. dot.gov/PIDP%20Grants/FAQs. 7 FTA (Federal Transit Administration). 2013. “Notice of Funding Availability for Resilience Projects in Response to Hurricane Sandy.” https://www.transit.dot.gov/regulations-guidance/ notices/2013-30867. 8 FEMA (Federal Emergency Mangement Agency). 2021. “Hazard Mitigation Assistance Grants.” https://www.fema.gov/grants/mitigation.

10 INVESTING IN TRANSPORTATION RESILIENCE in clear and reliable metrics that convey the degree of resilience already in the transportation system and that would be added by well-planned and targeted public investments in infrastructure and recovery capacity. Many considerations go into the prioritization of transportation investments, some of which are more quantifiable (such as traffic impacts) than others (such as quality of life impacts). In an environment where the risks and natural disasters are growing and their costs are escalating, the measure- ment of resilience is becoming even more important for making transporta- tion investment choices that are sound and do not leave the strengthening of this capability to chance. It is presumably that interest in making investment choices that are well informed by resilience considerations that led to the request for this study on metrics, the details of which are discussed next. STUDY CHARGE On December 20, 2019, the Further Consolidated Appropriations Act, 2020, Division H—Transportation, Housing and Urban Development, and Related Agencies Appropriations Act directed the U.S. Department of Transportation (U.S. DOT) to enter into an agreement with the National Academies of Sciences, Engineering, and Medicine (the National Academies) to conduct a study through the Transportation Research Board on effective ways to measure the resilience of transportation systems and services to natural disasters, natural hazards, and other potential disruptions.9 In commissioning the study in response to this legislative request, the U.S. DOT’s Office of the Assistant Secretary for Research and Technology and the National Academies negotiated the following more detailed State- ment of Task: The committee will identify and examine metrics that can be used to assess the resilience of existing infrastructure and inform the planning of investments in infrastructure for the surface, marine, and aviation modes of passenger and freight transportation. Consideration will be given to the types and key features and qualities of metrics that can inform investments intended to increase the resil- ience of transportation system assets and their critical functions following natural disasters as well as for longer-range resilience planning for a wide array of natural hazards such as hurricanes, floods, wildfires, heat waves, 9 P.L. 116-94, Further Consolidated Appropriations Act, 2020, Division H— Transportation, Housing and Urban Development, and Related Agencies Appropriations Act, 2020, Title I, Department of Transportation, Office of the Secretary for Research and Technology, 133 Stat 2534, 2934, December 20, 2019. https://www.congress.gov/116/plaws/publ94/PLAW- 116publ94.pdf.

INTRODUCTION 11 high winds, and changing freeze-thaw patterns. The kinds of data, meth- odologies, and analytic tools needed to design and apply such metrics will be examined as well as to evaluate their relevance and prioritize their use. Consideration will be given to metrics described in the literature and being used, developed, or recommended by federal agencies, state, tribal, and local governments, metropolitan planning organizations, and other public and private transportation practitioners. Based on the findings of this review, the committee will make recommen- dations, as appropriate, on how metrics can be developed, improved, and applied to make more informed decisions such as when to employ higher design and construction standards and when to increase investments over- all to strengthen the resilience of transportation infrastructure and systems. The committee will give special attention to metrics that can be applied by Congress and other policy makers to inform decisions about when and how much to invest in transportation resilience, and how to design infra- structure funding programs that prioritize resilience. STUDY SCOPE AND APPROACH To conduct the study, the National Academies appointed an interdisciplinary committee of 12 members with expertise in multiple modes of transportation, transportation resilience management and analysis, economics, risk analysis, and decision-aid tools. Beginning with the study charge, as articulated in the Statement of Task, and in considering the legislative origins, the committee made several decisions about the study scope that shaped the study approach. As the Statement of Task describes, Congress is looking at resilience from the perspective of making decisions about appropriating funds for up- grading transportation infrastructure to address natural disasters through- out the country. The decision to fund upgrades is relevant to infrastructure needing replacement, requiring restoration after a disaster, and being planned for new service. Upgrading can be accomplished through diverse actions, for instance by • Building resilience into transportation infrastructure already in service, for example, by retrofitting bridge piers or adding restrain- ers to beams to protect against a potential earthquake that could threaten the structural integrity and functionality of the bridge; • Rebuilding assets that are coming to the end of their life to up- graded standards that improve their resilience to natural disasters and climate change stressors; • Rebuilding assets that are damaged by a natural disaster and stressors to a higher, more resilient standard; • Adding to or improving networks to add redundancy;

12 INVESTING IN TRANSPORTATION RESILIENCE • Relocating assets of a transportation network to sites with lower risk of stress and damage; or • Enhancing design standards for new infrastructure to improve resilience to natural disasters and changing climate conditions. The infrastructure for the U.S. highway system is largely owned by pub- lic agencies, for example, state departments of transportation and municipal governments, while services are provided by drivers and firms owning and operating their own vehicles to serve passengers and freight. On the other hand, railroads—and in some instances, mass transit systems—are vertically integrated, with the same entity owning and maintaining the infrastruc- ture and delivering the services. While a state DOT or municipality may logically focus resilience planning on its infrastructure, vertically integrated service providers must consider all assets essential for delivering service. This underscores the importance of adopting a broad view of transporta- tion services in resilience planning, including caring for and investing in physical assets and the skilled people to plan, operate, and maintain them; rolling stock; energy sources; and control systems. It also requires putting in place operating strategies appropriate to this purpose. In keeping with the legislative request for this study and the sponsor’s charge, however, the committee focused its efforts on the state of practice and research literature aimed at making the major physical assets of the transportation modes and their networks (such as those assets listed in Table 1-1) more resilient to natural disasters and changing climate conditions. The congressional statutory mandate for this study cites natural disasters, hazards, and other potential disruptions in broad terms, and the committee’s definition of natural hazard includes not only significant acute weather and geophysical disturbances (e.g., hurricanes, earthquakes) but also longer-term (chronic) stressors (e.g., sea level rise, changing temperature and precipitation norms), some of which are exacerbated by climate change. This study commenced during the onset of the COVID-19 pandemic. There- fore, the committee considered early in its deliberations whether resilience to a pandemic should be included directly as a subject matter of the study and its recommendations. The study committee concluded, however, that it should focus on methods, tools, and measures that will help transporta- tion decision makers determine which investments are needed to enhance the physical infrastructure’s resilience, particularly with respect to the harm caused by natural disasters and stressors. Although pandemics are a natural hazard, they have few direct effects on the physical condition of transporta- tion infrastructure. Resilience to pandemics, therefore, is not given direct attention in this report. Because the measurement of resilience draws on concepts and practices developed in domains such as structural and geotechnical engineering,

INTRODUCTION 13 TABLE 1-1 Physical Infrastructure Assets for Transportation Modes Transportation Mode Physical Infrastructure Assetsa Road network Roads, bridges, tunnels, culverts, traffic signals, toll collection gantries/booths Maritime Docks, breakwaters, entrance channels, main basins, container yards, roads and rail lines, container freight terminals, warehouses Air transportation Airport terminals, runways, taxiways, control towers, aprons, hangars, access roads, heliports Inland waterways Channels, locks, dams, terminals Railroad Tracks, bridges, tunnels, culverts, yards, maintenance facilities, passenger stations, signal and traction power systems Transitb Tracks, bridges, tunnels, stations, signal and traction power systems, maintenance and storage facilities, bus roadways Pipelines Pipes, pumping stations, compressor stations, manifolds, storage facilities a Various transport networks are also supported by systems with control, monitoring, and communications functions, as well as fire, life, safety, and security capabilities. b Modes include, but are not limited to, bus, commuter rail, ferry, heavy rail, and light rail. emergency preparedness, hazard mitigation, asset management, business continuity, and anti-terrorism security, the language used for defining and measuring resilience varies. As entities and industries have borrowed and adapted concepts to suit their specific needs, the same terms have come to mean different things in different contexts. This variability in ter- minology and definitions (e.g., the meanings of hazard, threat, vulnerability, risk, and criticality) can complicate efforts to reach and convey a common understanding of what is meant by resilience and how it can be analyzed, measured, and deliberately enhanced. As the recent National Cooperative Highway Research Program publication Mainstreaming System Resilience Concepts in Transportation notes, “The terminology of resilience, particu- larly when considering extreme weather/climate change, has in the past included usage of the terms ‘vulnerability’ and ‘risk,’ often interchange- ably. The cross-pollination of these terms in the past has sometimes sown confusion in the transportation field.”10 Box 1-1 contains definitions of key terms and concepts as they are used in this report, recognizing that these definitions may not apply when the terms and concepts are used in other contexts. 10 NASEM (National Academies of Sciences, Engineering, and Medicine). 2021. Main- streaming System Resilience Concepts into Transportation Agencies: A Guide. Washington, DC: The National Academies Press, p. 128. https://doi.org/10.17226/26125.

14 INVESTING IN TRANSPORTATION RESILIENCE BOX 1-1 Definitions Adaptive capacity—Ability of a system to adjust, repair, and respond to damage or disruption.a Climate change—Changes in average weather conditions that persist over mul- tiple decades or longer. It encompasses increases and decreases in temperature and changes to features of the climate systems, such as shifts in precipitation.b Criticality—Importance or value of infrastructure asset, in terms of the cost to users, owners, and society from a loss in functionality. Disruption—Degradation of system functionality due to a hazard. Exposure—Whether an asset experiences a stressor.c Natural hazard—A natural phenomenon that can produce damaging disruptions on systems and their functionality.d Resilience—The ability to prepare for and adapt to changing conditions and withstand and recover rapidly from disruption.e Risk—The potential for loss of functionality of a system from exposure to a hazard that exploits its vulnerability. The value or cost of that loss.f Sea level rise—Increase in the volume—and thus, elevation level—of the world’s oceans resulting from global warming. There is a large body of research on resilience and resilience metrics but some disconnect between the research and practical applications, which, not surprisingly, lag behind the research. In its work, the committee examined both research and practice and worked to build connections between the two, with the focus on making recommendations about advancing the practice. To learn about existing approaches to measuring the resilience of trans- portation infrastructure and how agencies approach investment decisions with resilience in mind, the committee held several information gathering sessions with panels of experts from a diverse set of transportation modes. They included experts in seaports, airports, inland waterways, railroads, highways, and regional planning. Among the regional, state, and federal agencies consulted were the Federal Highway Administration, FEMA, the U.S. Army Corps of Engineers, the Port of Long Beach, the San Diego

INTRODUCTION 15 Sensitivity—Whether the asset may be damaged or disrupted by the stressor.g Vulnerability—Potential for harm to system functionality due to disruption caused by a hazard. Vulnerability is a function of the characteristics—scale and scope— of the hazard and the location, design, and condition of the infrastructure asset.h a FHWA (Federal Highway Administration). 2015. “Climate Change Adaptation Guide for Transportation Systems Management, Operations, and Maintenance.” https://ops.fhwa.dot. gov/publications/fhwahop15026/fhwahop15026.pdf. b Reidmiller, D.R., C.W. Avery, D.R. Easterling, K.E. Kunkel, K.L.M. Lewis, T.K. Maycock, and B.C. Stewart, eds. 2018. Impacts, Risks, and Adaptation in the United States: Fourth National Climate Assessment, Volume II. Washington, DC: U.S. Global Change Research Program. https://doi.org/10.7930/NCA4.2018. c FHWA. 2015. “New Tool Helps Agencies Manage Transportation Assets in the Face of Climate Change.” https://www.environment.fhwa.dot.gov/Pubs_resources_tools/publications/ newsletters/feb15nl.pdf. d NRC (National Research Council). 2012. Disaster Resilience: A National Imperative. Washington, DC: The National Academies Press. https://doi.org/10.17226/13457; NIST (Na- tional Institute of Standards and Technology). 2016. Community Resilience Planning Guide for Buildings and Infrastructure Systems, Volume 1. NIST Special Publication 1190. http:// dx.doi.org/10.6028/NIST.SP.1190v1. e The White House. 2013. “Presidential Policy Directive 21: Critical Infrastructure Security and Resilience (PPD-21).” f NRC. 2012. Disaster Resilience: A National Imperative. Washington, DC: The National Academies Press. https://doi.org/10.17226/13457; B.M. Ayyub, ed. 2018. Climate-Resilient Infrastructure: Adaptive Design and Risk Management. Manual of Practice 140. American Society of Civil Engineers. g FHWA. 2015. “New Tool Helps Agencies Manage Transportation Assets in the Face of Climate Change.” https://www.environment.fhwa.dot.gov/Pubs_resources_tools/publications/ newsletters/feb15nl.pdf. h NRC. 2012. Disaster Resilience: A National Imperative. Washington, DC: The National Academies Press. https://doi.org/10.17226/13457. County Regional Airport Authority, several state DOTs, the New York Metropolitan Transportation Authority, and the Hampton Roads Trans- portation Planning Organization. The panelists are listed in the Preface and in Appendix B. The information gleaned from these panel discussions was invaluable to the committee in informing its deliberations that led to this report. After this series of discussions with modal experts and transportation practitioners, the committee realized that any recommendations on input data and output metrics (or measures) relevant to the evaluation of trans- portation resilience would have limited utility in the absence of information on how to derive and apply them. To that end, the committee sought to identify approaches for measuring transportation asset resilience and the potential benefits conferred from strengthening it.

16 INVESTING IN TRANSPORTATION RESILIENCE The committee carefully considered the feasibility of identifying a single or small set of metrics to characterize the resilience of transportation sys- tems and services. It quickly became apparent that such a unitary metric was unlikely to be found. Among the elements contributing to this deter- mination are the following: • Transportation itself is a complex combination of infrastructure, processes, and people that delivers many different services and functionalities. • Transportation operates in many highly varied contexts, across which threats from natural hazards, demand for services, and demographic and environmental conditions range widely. • Transportation assets comprise a broad range of infrastructure types, scales, ownership, and management patterns. While it is possible to measure the resilience of aspects of particular facilities and services in the face of specific hazards, aggregating across systems, services, hazards, and contexts to produce a singular or small set of metrics for a system or region is unlikely, a conclusion supported by the committee’s review of both the state of the practice and contemporary research. While measuring transportation resilience at any reasonable scale— community, state, or nation—is beyond the reach of practical tools, the committee found that it is possible to create a decision framework that would inform decisions about investments in transportation resilience. Such a framework considers characteristics of transportation assets, their vulnerability and criticality, and the natural hazards they are likely to face. This framework provides a series of analytical steps and suggested metrics for measuring resilience benefits in a logical and consistent manner so they can be weighed against the costs incurred to achieve them. The primary product of this report, therefore, is a framework for mea- suring resilience benefits in a logical and consistent manner so they can be weighed against the financial outlays and other costs likely to be incurred to achieve them. The committee envisions that such a resilience analysis framework would be part of the overall decision calculus for transportation infrastructure investments. REPORT ORGANIZATION The remainder of this report is organized into five chapters as follows: • Chapter 2 provides background about common natural hazards and climate change in the United States and, within that context,

INTRODUCTION 17 an example of the effects that such disruptions can have on major transportation facilities and systems. The chapter also relates the way natural hazards can be characterized for analysis purposes and describes several tools that historically have been used by transpor- tation planners to understand the natural hazards affecting their facilities. Chapter 2 thus provides important context for evaluating resilience. • Chapter 3 explores the current state of practice for evaluating resilience of transportation facilities and systems and evalu- ating resilience-related investments. It includes a variety of exam- ples of resilience analyses, and it concludes with an overview of the metrics practitioners are using for resilience planning. • Chapter 4 reviews resilience analysis approaches and metrics in the research literature. • Based on the information about the state of practice and research, Chapter 5 offers a multi-step framework to provide decision makers with a general methodology for evaluating candidate actions to best increase the resilience of at-risk transportation facilities. The chapter also presents a portfolio of input data and output measures for use during the various steps of the framework. • Chapter 6 presents the study recommendations and their rationales.