Dynamic dispatch policies for emergency response with multiple types of vehicles

Abstract

Emergency medical service (EMS) systems have two main goals when sending ambulances to patients: rapidly responding to patients and sending the right type of personnel to patients based on their health needs. We address these issues by formulating and studying a Markov decision process model that determines which type of ambulances (servers) to send to patients in real-time. The base model considers a loss system over a finite time horizon, and we provide a model variant that considers an infinite time horizon and the average reward criterion. Structural properties of the optimal policies are derived. Computational experiments using a real-world EMS dataset show that the optimal policies inform how to dynamically dispatch ambulance types to patients. We propose and evaluate three classes of heuristics, including a static constant threshold heuristic, a greedy heuristic, and a dynamic greedy threshold heuristic. Computational results suggest that the greedy threshold heuristic closely approximates the optimal policies and reduces the complexity of implementing dynamic policies in real settings.