Load scheduling of multiple yard crane systems in container terminal with buffer areas

This paper addresses the load scheduling problem of multiple yard crane systems in container terminals with buffer areas. In the problem several yard cranes are used to pick up a sequence of containers for a quay crane. The containers picked up ahead of schedule can be stored in buffer areas until they can be handled by the quay crane. An integer programming model is developed for the problem formulation. In the model the work schedules of different yard cranes are decided simultaneously to minimize the loading time. The yard crane scheduling problem is NP-complete by nature. Therefore a scheduling heuristic is designed to solve the proposed problem. Numerical experiments are conducted to compare the performance of the multiple yard crane systems in container terminals with and without buffer areas.