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Transportation networks are one of several critical infrastructures on which first responders rely in order to deliver emergency services. However, there is no guarantee that a transportation network will be fully operational following a regional event, such as a hurricane or earthquake. Emergency planning and response tools should explicitly integrate this possibility to ensure the completeness of the risk assessment process. This paper considers the elevated vulnerability to which a community is exposed when disruptions in a transportation network slow emergency response. An average weighted vulnerability metric is defined to favor a network restoration strategy that quickly reduces emergency response times to their nominal levels. This metric is incorporated into an algorithm to prioritize network restoration, so that individuals who might require assistance are not exposed to prolonged periods of lengthy response times. The formulation considers a number of types of emergency response facilities and different types of hazard; the hazards can require a response from more than one type of facility. The utility of the approach is illustrated through a series of examples. Our results demonstrate that the approach can offer systematic guidance to reduce emergency response times after a partial or complete outage of a transportation network.

Homeland Security Presidential Directive-8 establishes a framework for national preparedness, including a vision, specific scenarios of concern, as well as a task list and target capabilities to be developed. The Department of Homeland Security Science and Technology Directorate has fostered enhanced resilience through sponsorship of tools to simulate the impact of the various disaster scenarios identified. However, the default simulations implemented for each of these scenarios implicitly assume availability of public transportation networks for task such as evacuation and response, yet such availability cannot be guaranteed without explicit consideration of the triggering events on transportation networks. Transportation is especially important as a majority of the scenarios indicate that over half of the affected population will need to be evacuated or selfevacuate and this population may be on the order of hundreds of thousands of people. Given the volume of traffic such scenarios may generate, the automobile transportation network will need to carry the majority of this flow of evacuees. Thus, methods to assess and mitigate the negative impact of transportation network disruptions on all aspects of disaster management, will be essential to reduce communal risk. This paper examines the criticality of public transportation in the context of the planning scenarios, suggesting methods to explicitly incorporate the impact of transportation network disruption. Methods based on dynamic traffic assignment are explored and applied to a small hypothetical scenario inspired by the 2010 Times Square car bombing attempt.