Scheduling trucks in a multiple-door cross docking system with unequal ready times

Abstract

Cross docking is a new strategy in logistics mainly consisting of unloading products from inbound trucks, resorting and loading directly into outbound trucks with minimum possible transitional storages. In this paper, we study the truck scheduling problem in a cross docking terminal with multiple receiving and shipping dock doors. The objective is to find the best door assignments, the docking sequences of both inbound and outbound trucks and also product assignments to trucks to minimise the weighted number of tardy trucks, when the ready times for inbound trucks, and different distances between the inbound and outbound doors are considered. The problem is formulated as a mixed-integer linear programming (MILP) model and since the optimisation problem is NP-hard, we suggest simulated annealing and genetic algorithms to solve the model. To evaluate the performance of meta-heuristics, we benefit from numerous different problem instances in the literature and compared the results to a pure random search algorithm and also to GAMS software results for the MILP model. [Received 23 July 2014; Revised 12 January 2015; Revised 30 April 2015; Accepted 20 May 2015]