Sequential ordering problems for crane scheduling in port terminals

The sequential ordering problem is a version of the asymmetric travelling salesman problem where precedence constraints on vertices are imposed. A tour is feasible if these constraints are respected, and the objective is to find a feasible solution with minimum cost. The sequential ordering problem models many real world applications, mainly in the fields of transportation and production planning. In particular, it can be used to optimise quay crane assignments. In this paper we experimentally evaluate the contributions of the basic ingredients of the state-of-the-art algorithm for the sequential ordering problems: local searches, ant colony and heuristic manipulation. Copyright © (2008) by CAL-TEK S.r.l