Determining the locations of emergency medical service facilities

This study deals with the problem of optimally locating and designing emergency medical service systems. The problem is formulated as a multi-source capacitated fixed charge facility location model. The model minimizes the total cost of meeting demand while guaranteeing a maximum service response time. In order to determine the locations and capacities of emergency medical service locations, defined in terms of the number of emergency service vehicles, service requests are first assumed deterministic. The uncertainty in service requests is then introduced using a scenario-based two-stage stochastic programming approach together with the concept of service levels that allows a maximum number of service requests being not responded. Both optimization models are coded in JAVA programming language and solved using the optimization solver CPLEX. For the deterministic model, a two-stage constructive heuristic is proposed; the performance of the proposed heuristic is evaluated in terms of the solution quality and solution time using a large set of problem instances. The impact of the changes in the problem parameters on the performance of the heuristic is also investigated.