Flood risk assessment and application of risk curves for design of mitigation strategies

A transportation network is a critical infrastructure system that forms the backbone for economy, serves the everyday life, and is critical to national safety. Holistic design of such a system is required to ensure smooth operation under both operational and emergency conditions. However, with ever-changing climate, transportation systems are exposed to significant weather-related hazards. For example, flood events are proven to be a dominant hazard in the U.S. due to their frequency and intensity. While flood events affect state agencies by requiring direct tax-dollar investments to repair damages, they also adversely influence communities by producing substantial indirect losses. This motivates state agencies, asset owners, and planners to developcost-effective mitigation strategies. However, the uncertainty of flooding and the interdependency between assets (such as roads and bridges) within the transportation system and traffic users on one hand and limited budgetary resources on the other hand, challenge the design of a cost-effective risk mitigation strategy. This is exacerbated by the fact that the estimation of indirect losses associated with closures resulting from damaged assets is difficult to assess. To address such gaps, this paper develops an integrated risk assessment method that synthesizes various inputs, including hazards, geographic features, spatial distribution of assets, and traffic, to simulate the flood-induced risk to a real-life transportation system. This framework is capable of estimating actual physical infrastructure damages as well as quantitatively evaluating the indirect losses of traffic users such as traffic delays and opportunity costs closely associated with flood risk. The developed flood risk curves can be used by decision-makers to implement proper pre-event mitigation or post-event response plans.