Simulation-based analysis for hierarchical storage assignment policies in a container terminal

This paper describes the structure and employment of a discrete-event simulation model for the real-life detailed processes performed during the handling of import containers. In particular, the model focuses on the storage assignment problem at the operational level in a container terminal with a multiple-berth structure. A novel approach using a hierarchical structure is adapted to partition the assignment problem into two sub-problems and solve each of them using separate decision rules. Suggested storage policies are evaluated in view of the overall performance of the container terminal. Different traffic densities are simulated to reflect the real-time environment. Simulation runs emphasize the bottleneck at the quay cranes. Results confirm that quay-crane efficiency may be improved by using appropriate storage policies. Strategies that adopted the integrated assignment method at the first level, where travel distances and gantry-crane workloads are considered, performed best at coping with this bottleneck. At the second level of the hierarchy, by using a segregated strategy, in which estimated container departure dates are considered, the number of reshuffles is reduced.