Integrating Discharge/Loading Services with Internal Transfer Services in a Maritime Container Terminal

The 2008 crisis-guided reverse has put an end to the continuous growth of containerized goods in the Mediterranean Area, while boosting, at the same time, gains for the logistic platforms in North Africa because of their low platform and labor costs. As a result, the platforms on the other side of the Mediterranean can only achieve competitive advantages through the ability to ensure a higher level of handling and storage services for container import and export. According to most of the literature on container terminals, this purpose is mainly served by optimizing both container discharge/loading (D/L) and yard organization. In previous modeling efforts, a queuing network was proposed to represent container D/L services in the quay area. This model took into account forking and joining features following which blocking and starvation phenomena were likely to occur, whereas yard operations were represented by pure delay stations. Here we consider integrated models in which D/L services interact with yard operations and, in particular, with specific internal transfer services called housekeeping. In this case, groups of containers undergo an "indirect discharge" to dedicated areas and are later transferred and repositioned by appropriate vehicles in other areas. In the transshipment terminal under analysis, internal transfer is based on a DTS system and yard space is organized in blocks. Internal transfer on the yard is provided by tractor vehicles which cycle between blocks. These tractors move empty multi-trailers to the source blocks for container loading and loaded multi-trailers to the destination blocks for container discharge. Straddle Carriers perform the discharge/loading operations by accessing the single rows in the yard area, while reach stackers directly provide empty containers from the blocks to the SCs for discharge/loading. For this complex service system, in which housekeeping is integrated into a overall queuing framework already accounting for vessel berthing, crane assignment, D/L operations and yard stacking, we exploit a Simulation-Optimization approach to determine the type and number of handling equipment required to minimize the vessel turnaround time.