The crane scheduling problem

This paper examines crane scheduling for ports. It starts with a simple static case and uses it as a building block to develop a better understanding of the dynamic problem with berth length limitations. The paper assumes that ships are divided into holds and that (usually) only one crane can work on a hold at a time. Cranes can be moved freely from hold to hold, and ships cannot depart until all their holds have been handled. In the most general case, ships arrive at different times and must queue for berthing space if the berths are full. The objective is to turn around (serve) all the ships, while minimizing their aggregate cost of delay. The paper presents exact and approximate solution methods for crane scheduling. The approximation methods are based on optimality principles and are easy to implement. The exact methods can only be used for a few ships. The paper includes examples, performance tests, and a discussion of port operations and further work.