An Approximate Cost-integrated Modelling Approach to Cross Dock Design

Cross docking is a form of operating break-bulk freight terminals in which the receiving products are not stocked but, instead, the incoming cargo is internally transferred to be immediately shipped in distribution trucks. With this approach, inventory costs and lead-times are significantly reduced. In this work, an approximate, continuous, non-stationary queueing model is established to estimate the number of cargo discharging doors in the receiving dock. Since the traditional first-come, first-served queueing discipline is not applicable to this specific problem, an alternative formulation, called least-distance, firstserved queue discipline, is adopted and analysed with a simulation approach. The problem is modelled to support a preliminary design of a cross-dock terminal. The objective function, to be minimized, is the sum of the rent cost of the terminal facility, the waiting cost of inbound trailers when being attended at the terminal, and the cost of handling and moving freight inside the terminal.