Cross-dock facility for disaster relief operations

In an emergency logistics operation, quick delivery and fair distribution of relief items are of extreme importance. Using direct shipments from suppliers to the affected areas for distributing relief items may be challenging because of scarcity of trucks after a disaster and underutilization of limited trucks due to direct shipments (i.e., full truckload shipments may not be achieved). A warehouse or a cross-dock may help overcome these challenges. Warehouses are essential for storing a predetermined level of goods for disasters. However, as a distribution center, they lack agility as there is a need for sorting, storage and order picking. In this paper, we incorporate the concept of opportunistic cross-docking (sending items directly from incoming to outgoing vehicles whenever possible) into emergency logistics operations as a means of more efficient delivery of relief items. Unlike the traditional cross-docking, where temporary inventory should be zero at the end of each period, the opportunistic cross-docking allows storage at the cross-dock facility. We compare cross-docking approaches for emergency logistics operations. After formulating the integrated cross-docking and distribution problems, we discuss several solution methods, namely: fix-and-relax, fix-and-relax combined with local search, local branching, and local branching combined with fix-and-relax. Computational experiments performed on three sets of randomly generated instances and a case study of Tehran’s district #1 data yield results in favor of opportunistic cross-docking. Furthermore, the solution methods are compared to each other and a commercial solver.