Optimal Supply Location Selection and Routing for Emergency Material Delivery

Supplying emergent materials for a disaster area in time plays a vital role in emergency response. Supply location selection and routing problem including warehouse selection and fleets scheduling and routing to guarantee to meet the demand in the required time window considered in this paper is a new and difficult problem and is proved to be NP-hard. The salient feature of this problem lies in the incorporation of the location selection into the problem. Moreover, every supply source can send a commodity to any customer such that the supply system makes full use of the commodities among different warehouses. The jam caused by heavy traffic is also considered in our problem. Clearly this problem is closer to the requirements in a practical emergency response system and is solved with ILOG CPLEX for a small and medium scale problem. The numerical testing results show that our problem formulation is valid and is difficult to solve. It is also shown that the total transportation cost increases as the demand deadlines become tighter and the number of commodities is larger. The computational times generally become intolerable for problems with more than 60 nodes.