Vehicle Scheduling with Time Constraint

We present methods for solving the vehicle scheduling problem with time constraint. Such problem consists of minimizing the costs related to the assignment of vehicles for performing a set of short trips. The vehicles are located at a single depot and one must consider the additional constraint that no vehicle can be away from the depot longer than a maximum time period. For two integer programming models we consider the corresponding Linear Programming and Lagrangean relaxations. The mathematical programming approach as well as a heuristic approach are tested on real-life problems.