A Multi-Period Location-Allocation-Inventory Problem for Ambulance and Helicopter Ambulance Stations: Robust Possibilistic Approach

Abstract

For saving as many as possible human lives, designing an efficient Emergency Medical Services (EMS) network seems necessary, especially by considering world complicated conditions, such as multi-facility locations and multi-transportation modes (e.g., ambulance and helicopter ambulance). The aims of this study are to locate the stations, allocate the accident-prone points to them, determine the required hospital bed capacities provided for patients with critical conditions, and decide about the inventory levels at opened stations including blood banks, medicines, etc. The model is subjected to resource limitation (e.g. budget and a limited number of helicopter ambulances). Since the real-world uncertainty stated by fuzzy numbers, a possibilistic method is used for solving the given problem. To immune solutions in front of fluctuation, it is combined with robust optimization; therefore, a robust possibilistic approach is used. Finally, an augmented ∈-constraint method is used to cope with the bi-objective problem that minimizes the cost and the arrival time. In practice, the model is applied to a real case.