A cost-based maritime container assignment model and port choice

Abstract

A recently proposed frequency-based maritime container assignment model (Bell et al, 2011) seeks an assignment of full and empty containers to paths that minimises expected container travel time, whereas containers are in practice more likely to be assigned to minimise expected cost. There are significant economies of scale in the maritime transport of containers; the cost per container per unit time falls with increasing ship occupancy and larger ships when full cost less per container per unit time than smaller ships. A cost-based container assignment model is proposed here. The objective is to assign containers to maritime routes to minimize sailing costs plus expected dwell costs at the ports of origin and transhipment. The constraints in the model are extended to include route as well as port capacity constraints. Although the cost per container per unit time depends on ship occupancy, it is shown that the problem remains a linear program. A small numerical example is presented to illustrate the properties of the model. The paper concludes by considering the many applications of the proposed maritime container assignment model.