Dynamic tugboat scheduling for container ports

Tugboat service is important for maintaining the safety and efficiency of ship movements in container ports. In practice, requests for tugboat service are not fully known when the planning horizon begins, but continually revealed while the existing tugboat scheduling is being performed. Thus, a tangible method is required to schedule tugboats to fulfill the continually arrived requests. However, there is no study on addressing this issue. Thus, we propose a dynamic tugboat scheduling problem, formulate the problem mathematically, and develop a tailored solution method that dynamically updates tugboat scheduling as new service requests arrive, so as to minimize the tugboat operation cost of whole planning horizon. We evaluate the effectiveness of the proposed solution method by comparing it with a benchmark method, and show that the solution method is able to achieve satisfactory performance within a reasonable computation time. In addition, we investigate managerial insights via computational experiments on a variety of instances created based on real-life container port operations.