A comparison of different solution approaches to the vehicle scheduling problem in a practical case

The Vehicle Scheduling Problem (VSP) consists in assigning a set of scheduled trips to a set of vehicles, satisfying a set of constraints and optimizing an objective function. A wide literature exists for the VSP, but usually not all the practical requirements of the real cases are taken into account. In the present paper a practical case is studied, and for it a traditional method is tailored and two innovative heuristics are developed. As the problem presents a multicriteria nature, each of the three algorithms adopts a different approch to multicriteria optimization. Scalarization of the different criteria is performed by the traditional algorithm. A lexicographic approach is followed by an algorithm based on logic programming. Finally, a Pareto optimization approach is implemented by a modified genetic algorithm. All the algorithms are tested on the real problem, and two of them produce interesting practical results.