BUS606: Operations and Supply Chain Management

The basic motivation of this study has been the necessity to analyze the queues generated at the unloading of products that arrive at a cross-dock terminal, a methodology not encountered so far in the literature. In fact, the vehicles must remain the minimum possible time at the terminal, only the time needed to be unloaded, letting their cargo to be internally transferred to the trucks that will deliver the cargo to the final destinations. To this respect, the employment of simulation modeling in the present work allowed for more realistic analysis of a cross-dock terminal operation. Specifically, it permitted defining a number of dock doors more compatible with the quantity of trucks received per day at the terminal, thereby reducing the congestion observed when unloading incoming vehicles, and consequently inducing a reduction of operating costs.

Through the simulation model we studied a specific application of the methodology to a cross-docking terminal of a supermarket chain. We obtained very similar results when applying a theoretical queuing model formulation, compared to the simulation analysis results. The advantage of employing a theoretical framework is the ease of computing via explicit mathematical formulas and numerical computation techniques. On the other hand, the use of simulation opens to the analyst a plethora of representation possibilities, allowing for a more detailed simulation approach level. Another simulation advantage is that it can detect possible bottlenecks in the system and produce graphical representations which are very handy in the discussion of system drawbacks and possible corrections.

It remains a need for more research investigation on this sector of logistics supply chain problems, namely, cross-dock design and operation. An associated problem to be tackled by researchers is the internal displacement of cargo units from the discharging doors to the areas allocated to shipping trucks. The assignment of trucks to doors in such a way as to minimize internal carrying costs might lead to substantial operational savings.

Finally, although it has been not easy to apply such modeling tools to real cases in developing countries like Brazil, due to empirical approaches and proprietary restrictions, the search for possible practical applications will be explored further. Presentation of such methodology possibilities at technical and academic conferences, many of them attended by transportation and logistics professionals, is a likely promising alternative.