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Suggested Citation:"Chapter 4 Conclusions and Research Recommendations." National Academies of Sciences, Engineering, and Medicine. 2020. Guidelines to Incorporate the Costs and Benefits of Adaptation Measures in Preparation for Extreme Weather Events and Climate Change. Washington, DC: The National Academies Press. doi: 10.17226/25847.
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Suggested Citation:"Chapter 4 Conclusions and Research Recommendations." National Academies of Sciences, Engineering, and Medicine. 2020. Guidelines to Incorporate the Costs and Benefits of Adaptation Measures in Preparation for Extreme Weather Events and Climate Change. Washington, DC: The National Academies Press. doi: 10.17226/25847.
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Suggested Citation:"Chapter 4 Conclusions and Research Recommendations." National Academies of Sciences, Engineering, and Medicine. 2020. Guidelines to Incorporate the Costs and Benefits of Adaptation Measures in Preparation for Extreme Weather Events and Climate Change. Washington, DC: The National Academies Press. doi: 10.17226/25847.
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Suggested Citation:"Chapter 4 Conclusions and Research Recommendations." National Academies of Sciences, Engineering, and Medicine. 2020. Guidelines to Incorporate the Costs and Benefits of Adaptation Measures in Preparation for Extreme Weather Events and Climate Change. Washington, DC: The National Academies Press. doi: 10.17226/25847.
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Page 28

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20 Chapter 4 – Conclusions and Research Recommendations The study team’s research found that transportation agencies are increasingly attempting to incorporate adaptation for extreme weather and climate change into capital planning, most often when capital assets are identified for replacement; however, DOTs cite uncertainty as an obstacle to regularly incorporating adaptation into their design practices. It is important to identify where uncertainty exists and where it does not, or where there is more and where there is less. Households typically take action when threats are even 1 percent or less for important assets and capital investments. Climate change is certain; over 99 percent of scientists agree on causes and effects, and models converge over time. The effects are serious and severe. Undertaking or continuing on the current path is very costly. What is unknown is how much the cost will be and what the trade-offs are. CBA can help with this critical need and can render climate change and its effects comprehensible and relevant to leaders, decision makers, and legislators, who must be given information and analytics from transportation professionals to estimate impacts. The fact that private sector real estate firms such as Zillow can perform straightforward analyses with federal data and estimates means that transportation agencies at all levels can, too. The need for this information and the trade-offs between the business–as-usual path and alternative paths cannot be overstated. Currently, transportation agencies infrequently conduct CBAs as part of planning and project development, usually only when it is required as part of funding source reporting or when the agency’s internal practices dictate its use. However, they acknowledge its usefulness as a potential tool for evaluating various options, particularly if the analysis can be done relatively easily using available data. Furthermore, there is growing emphasis from policy and funding entities to address cost-effectiveness of projects and increasing awareness of the need for climate resilience when DOTs experience more disruptions and damage. While no single tool or methodology currently offers a robust, resilience-centric CBA for the transportation network, there are frameworks, data, tools, and models that can be leveraged to develop a composite methodology that incorporates the relevant elements to comprehensively address climate change, resilience, and social, environmental, and economic considerations. The frameworks developed as part of this research enable practitioners to conduct a screening-level analysis to determine if adaptation to climate change is likely to be cost-effective. A more detailed climate resilience analysis allows practitioners to consider lifecycle costs, net present value of costs and benefits, and a benefit-cost ratio of potential adaptation options. Each level of analysis can be done using only financial data or can incorporate environmental and social considerations to the degree they can be quantified. Climate science is advancing steadily with respect to extreme precipitation, flooding, and sea level rise, and probabilities of these events occurring in the future under non-stationary conditions can be estimated for different scenarios. Potential damages associated with events of the magnitude witnessed recently, for example, can be evaluated and some of the damages, such as physical damages, detours, delays, and increases in accidents, can be estimated and quantified. Adaptation measures can be evaluated to estimate their impacts on decreasing risk and associated costs, and subsequently cost-benefit analyses can be completed to evaluate the NPV and BCR of each adaptation strategy. Similar approaches should be applicable to any event that has an associated return period. Research efforts also identified areas for future research and development: 1. Extreme Heat – The state of the practice appears to be less advanced with respect to extreme heat than to flooding and flood-related events. Additional research regarding considerations and

21 approaches for quantifying the impacts of extreme heat events/heat waves could benefit transportation practitioners in their understanding of costs and benefits in terms of continuity of operations and asset risk. 2. CBA Tool Development – DOTs indicated that the frameworks developed for this project are straightforward and easy to apply if all of the information is known. The perceived obstacle to using the frameworks is how and where to locate the data needed to perform the analyses. While the guidebook developed for this research includes a number of resources for finding this information, practitioners who are not familiar with these resources and/or not comfortable using them might be discouraged from completing CBAs for adaptation projects. A tool based on the frameworks could be developed to allow the user to select from a series of options that include or import/link to existing data sources to make CBA less intimidating. Wireframes for such a tool were developed as part of Task 4 and could be further conceptualized and developed into a working prototype tool. 3. Central Data Repository – Because CBA is reliant on data and many DOTs cited availability or understanding of needed data as a reason for not completing CBAs, a central data repository could be created to allow practitioners to access needed data through a central portal. Recognizing that each state has some data that is state- or geography-specific, the data repository would primarily house information and links to publicly-available federal data sources. Such a repository would need to be maintained indefinitely and updated periodically to incorporate new or updated data sources as they are developed. 4. National or multi-state analysis for transportation and public sector impacts, parallel to the holistic residential sector analysis performed by Zillow, based in National Oceanic and Atmospheric Administration (NOAA) and Intergovernmental Panel on Climate Change (IPCC) flood estimates for the business-as-usual scenario. What are the implications and what are the alternatives for transportation agencies? Implementation Plan Product Asset management planning processes are recognizing the need to consider and incorporate climate adaptation projects as appropriate into long-range plans and budget projections. Because of the uncertainty associated with future changes in climate as well as limited human and financial resources, DOTs desire to understand available resources and planning considerations that should help to inform decision-making processes regarding when, how, and to what degree to adapt. The guidebook developed for this research:  Provides a framework for DOTs to integrate climate adaptation and CBA into current planning processes;  Is a resource for state and local agencies desiring to evaluate cost-effectiveness of adaptation projects and mitigation approaches under consideration; and  Provides information on existing tools, methods, models, and data available to support CBA for climate adaptation and hazard mitigation projects.

22 Target Audience This research developed guidance and frameworks for DOTs and transportation practitioners to determine when and how to incorporate cost-benefit analyses into decision making regarding incorporation of climate adaptation into projects. The guidebook includes information regarding types of economic analyses and how each is typically used, considerations when selecting a discount rate for climate change conditions, summary information regarding climate conditions that might be trigger adaptation considerations, typical costs and benefits (often in terms of losses avoided) considered in CBA analyses, and frameworks for completing a sketch-level and climate resilience CBA. The guidebook is applicable to a wide variety of users faced with adapting to changing climate conditions. It will also be of interest to academic research bodies like the National Academies of Sciences, Engineering, and Medicine, and more specifically TRB. Application Changes to climate and extreme weather tax the effective operation of our transportation systems, and extreme weather events tend to leave damage and debris in their wake. Furthermore, certain types of extreme weather are increasing locally in either frequency, such as heavy precipitation events (e.g. Alexander et al., 2006 and Trenberth et al., 2007) or destructive potential, such as Atlantic hurricanes (Knutson et al., 2010). These changes represent a divergence from historical weather and climate patterns and increasing hazards for transportation assets and operations (e.g., NCHRP, 2014). For DOTs, increasingly frequent weather events present a connected set of issues with potentially serious, costly impacts on infrastructure; moreover, much of our nation’s transportation infrastructure is reaching the end of its useful life, and in some cases, competing priorities and limited budgets have resulted in underfunded preventive maintenance programs. In addition to extreme weather events, aging infrastructure is also being stressed by increases in population and development. Scientific studies widely show climate is beginning to exacerbate extreme weather. Higher temperatures mean more evaporation and moisture in the atmosphere and stronger storms, droughts, and heat waves. DOTs are preparing for:  Increased incidence and magnitude of extreme events common to the region  Unseasonal or unusual types of extreme weather hazards (Figure 4Figure 4)  The gradual shifting of climate zones outside the parameters for which infrastructure was designed (NCHRP, 2014), potentially reducing an asset’s lifespan, including: o Higher maximum temperatures Figure 4. EF3 tornado in Springfield, MA. On June 1, 2011, Massachusetts and southern Maine experienced seven tornadoes, mostly in the Connecticut River Valley. Tornadoes are uncommon in this region, and the 2011 event caused several deaths and damage to homes, businesses, and infrastructure.

23 o Depending on geography, wetter or drier climates o Changes to expected types of winter precipitation o Rising sea level In the face of changing climate and increased incidences of extreme weather, policies addressing cost- effectiveness can help DOTs make informed decisions about how to invest limited funds. In particular, CBA for climate adaptation helps provide a rigorous foundation for decision making, improving stewardship of limited public monies, and improving overall transportation system resilience. CBAs can strengthen the case for resilience investments, particularly as peak benefits usually occur later in the infrastructure lifecycle (Coley, 2012). Climate resilience means recognizing that extremes are not necessarily extraordinary, and effective CBA methodologies are needed to support efficient selection between project alternatives, allowing transportation agencies to prepare, respond, and recover quickly. Implementation One effective way to familiarize DOTs with the sketch-level and climate resilience CBA frameworks is through webinars. Based on the webinars and meetings conducted with DOTs as part of Task 6, a webinar lasting approximately 90 minutes allows the materials to be presented and explained and for participants to ask questions. In addition to webinars, in-person workshops lasting about 90 minutes could be conducted at conferences such as TRB and AASHTO annual meetings to explain the processes and materials. The webinars or workshops could be recorded and posted online to allow future users to access the training information. The guidebook would also be made available through normal online access through the TRB and NCHRP web portals. Impediments The target audience may be resistant to using CBA for several reasons cited during the research:  CBA is considered too time-consuming and labor-intensive  CBA requires too much data  Engineering practice already includes factors of safety; adaptation may not be needed  Uncertainties associated with climate change could result in completing analyses based on incorrect assumptions The guidebook includes examples and case studies that demonstrate how CBA can be useful in making adaptation decisions, some of which demonstrate adaptation is not cost-effective while others show that multiple approaches can be cost-effective. It also includes tables that summarize existing tools and data sources with web links whenever possible to make searching for information easier for users. Worksheets with examples are also included to provide users with step-by-step guidance on applying the frameworks. Judging Progress A tally of the number of webinars and/or workshops delivered, number of participants, geographic dispersion of participants, number of guidebooks requested and/or downloaded, number of web hits registered, and number of reprints can all be kept to measure the usefulness and acceptance level of the guidebook.

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Cost-benefit analysis (CBA) is useful for climate change response and adaptation, and if used properly, it has great potential for long-range planning. CBA should help agencies navigate the spectrum of decisions from mitigation and greenhouse gas reduction to adaptation: where does investing public funds generate the most public good?

The TRB National Cooperative Highway Research Program's NCHRP Web-Only Document 271: Guidelines to Incorporate the Costs and Benefits of Adaptation Measures in Preparation for Extreme Weather Events and Climate Change is published as a companion document to NCHRP Research Report 938. It includes two frameworks that were developed for the project to allow practitioners to conduct CBAs to a level of detail they deem appropriate; a sketch-level analysis can serve as a screening tool to evaluate if adaptation is even appropriate, while a more detailed climate resilience analysis can help to answer the question, “How much can I spend on an adaptation project and have it remain cost-effective?”

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