Scheduling Trucks in a Cross-Dock with Mixed Service Mode Dock Doors

The problem considered in this paper is how to schedule inbound and outbound trucks subject to time windows at a multidoor cross-dock. Dock doors can either be dedicated to inbound or outbound trucks or be capable of handling both truck types. In addition, loads are allowed to be temporarily buffered to bridge the time between load arrival and departure. We minimize operational costs consisting of the cost of handling loads in temporary storage, as well as the cost of tardiness caused by processing outbound trucks after their respective due times. A mathematical model is derived and an adaptive large neighborhood search heuristic is proposed to compute near-optimal solutions of real size instances. Computational experiments show that the proposed heuristic algorithm can obtain high-quality solutions within short computation times. We apply the model to cross-dock scheduling and design problems of four warehouses of a large retailer and show that substantially smaller cross-docks can be used by using dock-doors flexibly and properly scheduling the trucks.