A Bi-Level Mathematical Model for Hazardous Materials Transportation Network Design Problem Considering Response Planning

Hazardous materials (Hazmat) transportation and emergency response during Hazmat incidents is a very important issue in transportation field. In this paper, a new bi-level optimization model for Hazmat transportation network design is proposed. The bi-level framework involves a regulatory authority (government) and hazmat carriers. The government (upper level) affects the carrier's decisions by locating Hazmat emergency response stations and Hazmat network design. The government aims to maximize the coverage of network routes according to available budget. The coverage of routes means responding to Hazmat incidents. The carriers (lower level) by deciding on Hazmat flows and selecting transportation routes, seek to minimize their travel cost. Using KKT condition, we reformulate the non-linear bi-level model as a single-level mixed integer linear programming one which is solvable by an optimization solver like CPLEX. Through computational analysis, different aspects of proposed model are investigated to evaluate the model performance. The results show that increasing in coverage radius and risk tolerance result in higher network responsiveness.