Existing design standards and procedures may fall short in our goal of creating transportation infrastructure that is resilient with changing climate. Assumptions based on the past can be misleading when applied to the future. This presentation describes the proposed new design standards and procedures for designing roads and bridges to withstand inland flooding that enhance resilience to changes in climate. This research and development effort is part of the National Cooperative Highway Research Program (NCHRP) dedicated to applied research (Project NCHRP 15-80). Historically, inland flooding has been a significant consideration in the design of roadways and potential changes in climate may increase these stresses. Stressor characteristics include the nature and degree of the stressor, e.g., a flood with a peak flow of a certain amount. A stressor can be described using a target stressor, e.g., the 0.01 annual exceedance probability (AEP) flood, or a small number of target stressors. Alternatively, a stressor can be described using a range of characteristics for more detailed analyses. Specific assets of interest for this design flow process are bridges, culvert stream crossings, stormwater collection, and stormwater detention and retention. The presentation describes a new risk screening methodology that leads to recommendations for the level of analysis appropriate for specific road and bridge projects including when and to what degree future climate should be considered. The risk screening considers criticality, exposure, equity, and other factors that can be customized by transportation agencies. Not all projects are exposed in the same way and, therefore, many more routine types of projects will not demand intensive analysis. Conversely, some projects will benefit significantly from comprehensive analysis of risks and how a changing climate might affect those risks. The presentation will also describe proposed new standards for design that depend on the type of project and degree of climate risk. These new standards are based on taking the current AEP flood standards and providing multiple options for appropriate standards that consider the uncertainty related to climate change and the risk of flooding over the project lifetime. The proposed standards are simplified so that they can be easily integrated into the design process.
