Sequencing two cooperating automated stacking cranes in a container terminal

The containerized trade market is growing rapidly with the uprising of the Far East. Container ports worldwide should be responsive by developing tools to handle these massive volumes of containers in order to retain their level of competitiveness. One of the areas in a container terminal that is highly affected by the increase in the demand of containers is the stack. The stack is used to temporarily store containers upon further transport to their destination. This study is concerned with scheduling sea and landside storages and retrievals in a stack with two cooperating automated stacking cranes working in a single block. We present a mathematical model to minimize the makespan for both cranes. Both an algorithm to derive a lower bound for the makespan and a simulated-annealing based heuristic are proposed to efficiently solve the problem. Numerical experiments show that the solutions of the heuristic method are within 2% of the lower bound for large instances.