A Bucket Graph–Based Labeling Algorithm with Application to Vehicle Routing

We consider the shortest path problem with resource constraints arising as a subproblem in state-of-the-art branch-cut-and-price algorithms for vehicle routing problems. propose variant of bidirectional label-correcting algorithm which labels are stored and extended according to so-called bucket graph. This organization helps significantly decrease number dominance checks running time algorithm. also show how forward/backward route symmetry can be exploited eliminate arcs from graph using reduced costs. The proposed especially beneficial instances large capacity and/or window constraints. Computational experiments were performed on distance-constrained problem, including multidepot site-dependent variants, windows, “nightmare” heterogeneous fleet problem. Significant improvements over best literature achieved, many could solved first time.