Transportation Networks are a fundamental part of cities, allowing the flow of goods and people that are indispensable for the proper functionality of communities. However, these systems are formed by bridges and roads that may experience damage during an earthquake. It is in that regard that policymakers allocate money to prevent significant disruptions in traffic. Given the limited availability of resources, it is essential to define optimal strategies to invest public resources. In this study, we propose the retrofitting of Corridors as a strategy that minimizes the effect of earthquakes on traffic disruption, indirectly allowing for a faster recovery of the network, that is, a more resilient system. We define a Corridor as a set of bridges that works together to deliver a transportation service. Intuitively, a Corridor is a segment of an important road or a highway. For instance, Figure 1a shows a segment of the transportation network of the city of San Jose, and Figure 1b shows corridors with different colors that point to some specific segments of the system. To detect a corridor, we use the Markov Clustering Algorithm. Once sets of Corridors are defined, we perform a two-step stochastic optimization to choose actions to manage the transportation network, which can be two: retrofitting the bridges in a corridor before the disruptive event or repairing the damaged bridges after an event. After proposing a set of bridges to retrofit, the evaluation of the policy comes from a probabilistic assessment of travel time increase for hazard-consistent seismic scenarios.
Given that the retrofitting strategy is subject to the results of the clustering process, we also present different trends and guidelines of Corridors selection. As a conclusion of this study, we observe that the implementation of the Corridors Optimization approach in the San Francisco Bay Area yields better relative performance than other management approaches, such as considering bridges as individual entities or using graph centrality measures to rank them. Besides the improvement in performance, the use of corridors as a technique to select bridges to perform a seismic retrofit is closer to the current processes followed by decision-makers in transportation agencies.