A many-objective framework to design the restoration of damaged bridges on a distributed transportation network

Bridges serve as critical links in a transportation network. Closure of bridges due to damage resulting from an extreme event, such as an earthquake, can disrupt the transportation operations on the network leading to, potentially significant, economic and social losses. Rapid and simultaneous restoration of all damaged bridges is an ideal solution for minimizing these losses. However, this solution is not realistic for extreme events that might damage hundreds of bridges when considering limitations on the available financial and physical resources. Optimal restoration solutions, i.e. restoration designs, for disrupted transportation networks have been studied in the past. Most of these studies have relied on maximizing or minimizing one or two technical objectives, such as network functionality and restoration costs. However the restoration of a disrupted transportation network is necessarily complex due to the various economic and social aspects that need be considered, for example lost opportunity and mobility of citizens. A framework based on a many-objective approach, i.e. more than three objectives, that considers a broader array of technical, social and economic aspects so that robust solutions for the restoration design of damaged bridges on a distributed network can be identified is presented in this paper. The many-objective framework is applied to an example network to obtain robust solutions and compare these solutions to those obtained from optimization considering one and two technical objectives.