A Risk-Reduction Approach to Roadway Infrastructure Adaptation Prioritization for Improved Public Protection.

Measures to safeguard transportation infrastructure from uncertain hazard events, such as a flooding event, are crucial for public safety, but require significant investment. As it is impractical to try to protect all assets from all possible futures, a risk-based analysis approach for choosing a best protective strategy for adaptation can prove useful. This paper proposes and applies a need-based, risk-reduction methodology to more deeply understand how alternative approaches to mitigating risk via protective infrastructure investments can affect our neighborhoods. A risk measure, based on remaining connectivity to critical facilities, is employed that gives more weight to neighborhoods (represented by census tracts) that have the greatest gap in protection and, therefore, are at greatest risk of being disconnected from critically needed services. The measure is compared against four alternative investment strategies. The analysis is applied to a study area in the Washington, DC metropolitan area under a variety of hazard modeling assumptions. Trade-offs using ten distinct performance metrics are made. The results demonstrate that the choice of risk model in protective investment planning can greatly impact the recommended adaptation plan and which neighborhoods "win" and which "lose." The suggested method provides a balanced distribution of risk and may be a more acceptable approach for setting community protective investment priorities.