Integrated quay crane and yard truck scheduling for unloading inbound containers

To lower vessel turn time, it is crucial that the operations of quay cranes, yard trucks, and yard cranes are well coordinated. Most studies have sought to optimize each of these processes independently. Since the operations by quay cranes and yard trucks are highly interrelated it is necessary to develop and solve these operations in an integrated manner that reflects the characteristics of the marine container terminals. This study developed a mixed integer programming model for scheduling quay cranes and yard trucks jointly. The integrated model explicitly considered real-world operational constraints such as precedence relationships between containers, blocking, quay crane interference, and quay crane safety margin. To solve the integrated optimization model, a genetic algorithm (GA) combined with a greedy algorithm was developed. The results indicated that the solutions obtained from the integrated model are superior to those obtained from the non-integrated approach. The GA solutions demonstrated that the developed integrated model is solvable within reasonable time for an operational problem.