Fleet management for ambulance transports

Details :

Many emergency service providers and companies who provide non-public maintenance services meet the problem that their fleet of vehicles has to provide three different types of services: 1) Cover a certain region and be prepared for an emergency case. 2) Provide immediate service in an emergency case. 3) Provide some regular service (e.g.: dial-a-ride problems -- the pick-up and delivery of patients, predetermined service tasks, periodic pick-ups). In most cases the fleets are heterogeneous and some services can only be provided by specialized vehicles or workers. From the perspective of managing the regular services the objective is minimizing the total travelling distance subject to certain restrictions (e.g. be on time, use the appropriate vehicle, ..). Two types of the transportation services, emergency services as well as regular dial-a-ride services, have to be realized with one fleet.Therefore, specific dynamic aspects influence the schedule for the regular service. When an emergency occurs and an ambulance vehicle is required, the vehicle with the shortest distance to the emergency is assigned to serve the emergency patient. Therefore, it can happen, that an ambulance vehicle which has to carry out a scheduled transport order of a patient, which is not started yet, is used to serve the emergency patient and the schedule for the regular services has to be reoptimized and another vehicle has to be reassigned to the regular patient.Besides the constraints in classical Dial-a-Ride Problems we have the following features of our problem: 1) different (hard as well as soft) time constraint types.¿ e.g. dialysis patients must arrive exactly on time because the dialysis machine is reserved. 2) Heterogeneous fleet - We deal with a heterogeneous fleet concerning capacities of the vehicles and concerning the different available equipment on the vehicles. 3) Dynamic aspects - Some orders are known in advance. Additionally, the vehicle availability changes dynamically. The reason is the disappearance and reappearance of vehicles (emergency requests are serviced with the same fleet). 4) Stochastic aspects - Expected return transport orders (relatively long planning horizon), expected availability of vehicles, expected transport orders (relatively short planning horizon, in some cases emergencies occur and most probably additional vehicles are required.)

Start Date : 01.01.2006

End Date : 30.11.2009

Webpage : http://qse.ifs.tuwien.ac.at