Transportation officials are increasingly faced with challenging decisions about how to design, plan, and manage infrastructure to confront changes in climate and extreme weather events. An understanding of which impacts affect infrastructure and at what point damage begins to occur is a critical step toward assessing overall vulnerability and risk. However, few resources exist to help managers and designers identify key thresholds and indicators of sensitivity to weather and climate impacts. This paper introduces a sensitivity matrix, a tool developed for the U.S. Department of Transportation's Gulf Coast Study, Phase 2, adaptation pilot project in Mobile, Alabama. This matrix is an important step toward a more comprehensive understanding of relationships between climate and transportation. Transportation planners can use this matrix to screen for assets that are particularly sensitive and, therefore, potentially vulnerable to climate change. Where possible, the matrix includes key thresholds at which damage may be observed. This resource can assist the transportation community in conducting climate vulnerability and risk assessments. This sensitivity matrix reveals three main conclusions about the sensitivity of the transportation system to climate stressors. First, transportation assets tend to be more sensitive to extreme events than to incremental changes in the mean of climate variables. Second, services such as maintenance, traffic conveyance, and safety often are more sensitive to climate stressors than are physical assets. Finally, an asset is often sensitive to stressors whose occurrence is relatively unlikely in comparison with typical weather variability.

From installing culverts with larger safety margins to instituting more frequent training for weather emergencies, transportation agencies around the world are adapting to extreme weather and climate change. An understanding of when and how to adapt (i.e., improve infrastructure preparedness) requires evaluating existing and future vulnerabilities to climate change and prioritizing adaptation efforts. A successful vulnerability assessment lays the groundwork for adaptation by building stakeholder relationships, spurring data collection, and prioritizing needs. One barrier faced by transportation agencies in conducting vulnerability assessments is a lack of financial and staff resources. The process of collecting climate and asset data can be particularly onerous for agencies struggling to meet daily operational needs. Two recent projects piloted a cost-effective screening method for highly vulnerable assets that used indicators developed from data already being collected by many state departments of transportation and metropolitan planning organizations. The indicator that libraries developed during the course of these two studies is described. The results of the data-driven vulnerability screen provide transportation managers with a low-cost starting point toward understanding their system's vulnerabilities. Future research should focus on testing the indicators to identify and eliminate areas of overlap and on evaluating the prediction accuracy for exposure, sensitivity, and adaptive capacity.

Although many state and local transportation agencies recognize the need to make transportation assets more resilient in the face of a changing climate, there have been few methods and best practices they can draw on to determine which assets may be compromised under future conditions and how to evaluate and select adaptation measures. Federal Highway Administration’s (FHWA’s) Transportation Engineering Approaches to Climate Resiliency project sought to synthesize lessons learned and innovations from a variety of recent FHWA studies and pilots to help transportation agencies address changing climate conditions and extreme weather events at the asset level. This paper describes considerations for why, where, and how to integrate climate considerations into the project development process. It also discusses the types of climate information that should be considered, and summarizes lessons learned from FHWA’s studies and pilots—such as implementing adaptive designs, considering assets in a regional context, and exploring ecosystem-based adaptation solutions—that can be used to guide the process of developing adaptation strategies.

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