A Branch and Price Algorithm for a Static Ambulance Routing Problem

Abstract

Emergency Medical Service (EMS) systems provide life-saving support to people in emergency situations via first aid treatment and emergency transport to medical facilities. Such systems must strive to make the best use of their limited resources; they have thus been studied in the context of static and dynamic vehicle routing problems. In this work, we study a static ambulance routing problem aiming to minimize the weighted sum of patients' waiting time while considering ambulance compatibility, patients' priorities, ambulance redirection, and ambulance reassignment. We implement an exact Branch-and-Price algorithm over a Set Partitioning Formulation, study the results of this algorithm, and compare them to previously studied online heuristics using data from Rio de Janeiro's public SAMU system. The results obtained allow us to assess the value of perfect information in such systems, providing a comparative baseline for subsequent developments of online algorithms.