Two server dynamic coverage location model under stochastic travel time

This paper describes an optimization location model that minimizes the number of two kinds of ambulances, which are; advance life support (ALS) and basic life support (BLS), while meeting the coverage requirement. The purpose of this research is to improve the performance of the emergency medical service (EMS) by developing a two-server dynamic covering location model (TS-DCL). This model is considered with realistic operating conditions for the EMS system that is solved using a developed incremental search algorithm (ISA). The TS-DCL model includes the stochastic nature of travel time in response to service, so the ambulance location model becomes more realistic. Also, the approximate hypercube model is used to determine the dependence of ambulance busy fractions. An experimental study is carried out to examine the effects of the proposed model on the design of the ambulance services system. It is also including the application of the proposed model to a 144-node problem representing Al-karkh District in Baghdad City in Iraq. The experimental study shows that the TS-DCL model requires at least 26 ALS, 12 BLS backups and 24 BLS ambulances to meet the 95% coverage requirement of both the critical and non-critical calls.