Optimization of Transportation-Infrastructure-System Protection Considering Weighted Connectivity Reliability

Abstract

This study proposes a model and a solution method to optimize protection planning for transportation-infrastructure systems such as highway networks, which are subject to disasters given a limited budget. When links of a highway network fail because of disasters, the connectivity of the highway network can be damaged and travel demand cannot be served. In this study, a situation is considered when links of a highway network can be protected against disasters to maintain its connectivity. Given that damage to a highway network caused by a disaster is probabilistic, a two-stage stochastic programming (SP) model is developed to identify the optimal protection plan that maximizes connectivity reliability for highway networks. The measure of connectivity reliability is defined as the expected number of origin–destination pair groups that can be served under all scenarios of link failure caused by a disaster. The main contribution of the model formulation is that the travel cost of alternative paths and (normal or postdisaster) travel demand can be simultaneously considered in the optimization. As the probability of failures caused by a disaster can be extremely low, the required number of scenario samplings to obtain accurate estimates for connectivity reliability could be large, which causes computational difficulty for solving the SP problem. Therefore, a solution method is developed to practically solve the SP model. The proposed methodology is demonstrated with a highway bridge system that is subject to earthquakes. Results show that the proposed model has potential for improving the connectivity reliability of highway networks that are subject to disasters.