Sequencing storage and retrieval requests in a container block with multiple open locations

Abstract

We study the integrated problem of allocating containers and scheduling a yard crane in a block with multiple input/output (I/O) points. The crane moves each storage container from an I/O point to a location selected from a set of open locations. A location may be suitable to stack different containers. The crane moves retrieval containers from retrieval locations to I/O points. The objective is to minimize the total travel time. We model the problem as a generalized asymmetric traveling salesman problem with overlapping sets of open locations. A three-phase solution method and heuristic algorithm are developed to solve the problem.