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-andPrice 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.