Evaluating ship-to-shore schedules using simulation

During military operations in coastal regions, resources, such as personnel and vehicles, are brought from large amphibious ships to the shore using smaller ships and helicopters. The aim is to transport these resources as fast as possible while adhering to different types of constraints. This is called the ship-to-shore problem and has been solved assuming deterministic parameters regarding the speed and (un)loading time of the connectors. These schedules might therefore not be robust to delays. We developed a simulation model to analyze the effect of uncertainty in these parameters on the execution of a schedule. We analyze (1) whether these discrete time periods are able to capture the delays, (2) the effect of using more conservative parameters when constructing a schedule, and (3) the effect of being less rigid in the execution, i.e., when being allowed to depart a limited time ahead of schedule. We find that significant delays occur and that using more conservative parameters for the (un)loading time can have a positive significant effect on the duration of the operation. Being less rigid can also have a positive significant effect on the duration; however, it comes at the cost of violating constraints regarding the grouped delivery of resources.