Network-based Assessment of Resilience of Road Systems

Transportation infrastructure has been identified by the US Department of Homeland Security as one of sixteen critical infrastructure systems essential to the well-being of modern society. In this study, we propose a resilience-based framework for mitigating risk to road systems, considering both community and regional scales. We utilize recent developments in modern network theory to introduce a novel indicator based on system reliability and network connectivity to measure resilience and resilience improvement of a road transportation network. Our formulation systematically integrates the network topology, redundancy level, traffic patterns, and functionality during a community’s post-disaster recovery period, includes structural reliability (failure probability) of individual bridges in the network, and permits risk mitigation alternatives for improving transportation network resilience to be compared on a common basis. We propose a project ranking mechanism for identifying and prioritizing bridge maintenance or retrofit projects that are critical for effective pre-disaster risk mitigation of bridge systems. We provide a decision methodology to select optimal solutions among possible alternatives when the prospect of new construction offers opportunities to improve the resilience of the network by altering its existing topology. Finally, we conclude with an illustration of this resilience-based risk mitigation framework using a hypothetical bridge network susceptible to seismic hazards.