Coverage versus response time objectives in ambulance location

Abstract

Background: This paper deals with the location of emergency medical stations in a large-scale area. Operations research tools are used to design a new infrastructure that reflects demographic changes.Methods: A bi-criteria mathematical programming model is proposed. The criteria include the accessibility of high-priority patients in a short time limit and response time of all patients. The model is compared with the p-median model with a single response time objective and with a hierarchical pq-median model that considers different vehicle types. A detailed computer simulation model is used to evaluate the solutions.Results: The methodology is verified in the conditions of the Slovak Republic using real historical data on ambulance trips. Considerable improvements regarding the average response time, coverage of population and coverage of high-risk patients can be achieved by redistributing current stations. In a large-scale area, the coverage objective does not work well. It does not outperform the response time objective that enables saving more lives. The best results are achieved by the hierarchical median-type model.Conclusions: The resulting distribution of ambulances significantly improves the accessibility of urgent health care to patients.