Neighborhood Strategies for the Truck Dock Assignment Problem in Cross-Docks

In this paper, we are interested in the truck dock assignment problem in cross-docks with several constraints. A cross-dock is a warehouse with limited storage capacity. Arriving trucks are assigned to docks and have to deliver goods to a warehouse. These goods are sorted out and loaded into the outbound trucks immediately. The objective is to find an optimal dock assignment for each truck in order to minimize the cost of transferring shipments within the cross-dock while avoiding delivery problems. To solve this problem, we propose several meta-heuristics. The first one is a local search that is characterized by different neighboring operators. These operators are tested and compared one by one on various instances of the cross-docking problem. The second metaheuristic is a Variable Neighborhood Search (VNS). According to the efficiency of the local search operators, we test the way they can be combined in a VNS structure. Our experimental study shows that VNS makes use of the operators depending on their properties.