Maximal Covering Location Model for Doctor-Helicopter Systems with Two Types of Coverage Criteria

Abstract

This paper considers the introduction of doctor-helicopter systems into an existing ground ambulance system. The doctor-helicopter delivers an emergency medical doctor at or near an accident point to provide primary care to patients. Since helicopters cannot always land at demand locations, rendezvous points are required at which heli-copters can meet an ambulance carrying the patient. We propose a maximal covering location model that determines the locations of the helicopters and the rendezvous points simultaneously. Two types of coverage criteria are considered. The first type of coverage is achieved when a patient can access primary medical care within a given time by helicopter but cannot reach a hospital within the same time by ambulance. In the second type, each location is covered when a helicopter can reduce the trans-port time by more than a threshold time in comparison with access to a hospital by ambulance. The model maximizes the weighted sum of the total demands met by the first and the second types of coverage. We provide a 0-1 integer formulation of the model. Some optimal solutions of the model are analyzed by using geographical and population data, and the locations of the actual emergency medical centers in Japan.