Optimization of Container Terminal Unloading Operations Based Upon Multistage Flexible Flowshop Scheduling

Modeling unloading operations at maritime container terminals has increasingly become crucial to container terminal planners. This paper presents the multistage flexible flowshop scheduling problem (MFFSP). The objective of the MFFSP is to determine a schedule that minimizes the schedule length for a given number of containers and handling equipment over a finite planning horizon. Since the MFFSP is NP-hard in the strong sense, metaheuristic solution method is employed. A global lower bound to measure the efficiency of the metaheuristic procedure is derived. The optimization procedure is based on Genetic Algorithm (GA) which is used to estimate the minimum schedule length for a number of problem instances. Computational experiments validate the developed MFFSP.