Iterative improvement to solve the parcel hub scheduling problem

This paper presents iterative improvement algorithms to solve the parcel hub scheduling problem (PHSP). The PHSP is combinatorial optimization problem that consists of scheduling a set of inbound trailers to a small number of unload docks. At the unload docks, the inbound trailers must be unloaded and the parcel sorted and loaded onto outbound trailers. Because the transfer operation is labor intensive, the transfer of parcels must be done in such a way as to minimize the timespan of the transfer operation. Local search (LS) and simulated annealing (SA) algorithms are developed and evaluated to solve the problem. The performances of the algorithms are compared to the performance of an existing genetic algorithm (GA). The computational results show that the LS and SA algorithms offer solutions that are superior to those offered by the GA.