Formulating a mathematical model for container assignment optimization on an intermodal network

In this paper we deal with container assignment optimization on an intermodal network. We propose a linear programming model, following a frequency based approach, addressing both the maritime and the inland component, and taking into account custom times at ports and service frequencies. The proposed arc-based formulation, in which only variables related to arcs which actually exist are explicitly created, is particularly suitable for very large but sparse networks, typical in maritime long distance transport, because it allows strongly reducing the number of variables involved. Finally, we discuss computational results obtained on a real size instance.