The Fragility-Constrained Vehicle Routing Problem with Time Windows

We study a new variant of the well-studied vehicle routing problem with time windows (VRPTW), called fragility-constrained VRPTW, which assumes that (1) capacity is organized in multiple identical stacks; (2) all items picked up at customer are either “fragile” or not; (3) no nonfragile can be put on top fragile item (the fragility constraint); and (4) en route load rearrangement possible. first characterize feasibility respect to this constraint. Then, solve problem, we develop an exact branch-price-and-cut (BPC) algorithm includes labeling exploiting characterization efficiently generate feasible routes. This benchmarked against another BPC deals constraint column generation master through infeasible path cuts. Our computational results show former clearly outperforms latter terms has greater impact optimal solution cost (compared VRPTW) when decreases, stack height increases, for more balanced mix customers items.