Coordinated dock operations: Integrating dock arrangement with ship discharging

The operations of material docks involve two major tasks: dock arrangement and ship discharging. The former concerns the sequencing of ships waiting to be berthed for discharging whereas the latter considers the combinations of ship unloaders, conveyors and stackers, so that the total demurrage cost incurred is minimized. Apparently, different arrangements of the docks have different effects on the time required for the subsequent discharging operations. On the other hand, the arrangement of the docks is also affected by the time required for discharging. Hence, a careful coordination of these two tasks is deemed necessary. In this paper an interactive procedure which passes the necessary information between the two subsystems is devised to integrate the two tasks. This procedure is applied successfully to the material docks of the China Steel Corporation. Under complicated situations, the demurrage cost saved is estimated to reach 70%. An example is provided to stress that the performance of the integrated system is better than that of conducting the two tasks independently.