A Branch and Bound Algorithm for the Multiple Depot Vehicle Scheduling Problem

The Vehicle Scheduling Problem concerns the assigning of a set of time-tabled trips to vehicles so as to minimize a given cost function. We consider the NP-hard Multiple Depot case in which, in addition, one has to assign vehicles to depots. Different lower bounds based on assigment relaxation and on connectivity constraints are presented and combined in an effective bounding procedure. A strong dominance procedure derived from new dominance criteria also described. A branch and bound algorithm is finally proposed. Computational results are given