Dispatching and layout rules at an automated container terminal

We study an automated container terminal in which Automated Guided Vehicles (AGVs) are used to internally transport containers and Automated Stacking Cranes (ASCs) to store and retrieve containers. In designing container terminals, the terminal management has to consider the choice for interrelated AGV and ASC dispatching rules and the layout of the stack. In this paper, we, therefore, examine the joint decision problem of dispatching containers to AGVs, selecting ASCs and the layout of the stack. In choosing a certain combination of dispatching rules and layout, we have considered criteria, such as, unloading times of a ship, number of vehicles required and utilisation of equipment. From this specific study, we can conclude that hardly any differences in unloading times can be obtained if we choose another combination of AGV and ASC dispatching rules. However, savings of approximately 20% in the number of AGVs can be obtained, if we apply the nearest-AGV-first rule in combination with the cyclic ASC rule. The results of the layout experiments only show small variations in unloading times, but they justify further research to the options for ASCs to span a wider stack. From the sensitivity analysis, it can be concluded that Quay Cranes should be distributed as evenly as possible over the ship and that twin-load AGVs can be used to obtain significant savings in unloading times and up to 50% reductions in the number of AGVs required.