A transportation network facilitates the connectivity of local residential areas, improves capability for movement of goods, and contributes to economic development. Recent flooding events in the U.S. have highlighted the vulnerability of our transportation network to such events. Flooding, a predominant destructive hazard, leads to significant direct damages to physical road infrastructures and also results in significant indirect losses to communities that rely on the road network. Decision-makers, designers and planners all must understand the risks associated with such events and make adequate preparations for them. This paper proposes a holistic framework for integrating flooding hazards with vulnerability analysis of transportation road infrastructures, topologic risk analysis, and flow-based risk assessment. Vulnerability analysis of infrastructures reveals the extent of closure on roads and bridges. Topologic risk analysis, based on graph theory, provides immediate information on network characteristics that could be linked to instantaneous connectivity measures. Flow-based risk assessment uses a user equilibrium model to compute traffic time for the entire network for assessment of user losses from increased traffic time. Finally, the developed framework can be used to assess risks for a segment of the primary road system in the state of Iowa when facing flooding events with return periods of 2, 50, 200 and 500 years. It is expected that this integrated framework and the network performance measures could inform future resilience assessment and enhancement strategies in the studied region and provide a framework for other states that might wish to adopt this approach.
