Research on vessel scheduling strategies considering tidal constraints for port entry and exit

Efficient scheduling of large vessels entering and leaving ports is critical to improving port efficiency, particularly for ports affected by tidal constraints. This study investigates the ship scheduling problem in tide-influenced ports, incorporating tidal window constraints while accounting for berth size differences, vessel safety distances, and mooring/unmooring operations. A Mixed-Integer Linear Programming (MILP) model is developed with the objective of minimizing the total delay time of all vessels, and a Lagrangian relaxation heuristic algorithm is designed for its solution. A case study using real tidal data from the Ningbo-Zhoushan Wai Diao operation area was conducted. The results show that the proposed scheduling model and algorithm, which consider tidal window constraints, can reduce vessel delays by 28.5% while meeting safety requirements. This approach provides valuable insights for scheduling in ports significantly affected by tides.