Matheuristics for Waiting Time Minimization for Trailers with Uncertain Arrival Times

We present a new loading/unloading trailer scheduling problem for a logistics company.There is a building with several warehouses. Each warehouse stores pallets of different types ofproducts in rooms for loading into trailers. Each warehouse has two gates. One gate is for thetrailers, and the other one is for two forklifts from the central zone (production line). It producessome products which must be placed in warehouses according to the no wait rule. We assume thatthe arrival time for each trailer is uncertain. Our goal is to assign all trailers to warehouses andfind a schedule for servicing all the trailers with the maximum stability radius under the totalwaiting time constraint. For this NP-hard problem, we design a two-stage matheuristic. First, wesolve the simplified model using the Gurobi solver. Then the VNS algorithm is usedto return the solution into the feasible domain taking into account the detailed information aboutpallets in each warehouse. We generate some test instances using real data from a Dutch logisticscompany. Computational results for 6 warehouses, 18 types of products, and 90 trailers arediscussed.