The Interport: A Logistics Model and an Application to the Distribution of Maritime Containers

In a container transportation and logistics network, an interport is a common user facility located in the hinterland of one or several seaports where services are available to carriers and shippers such as transshipping, customs clearance and inspection, temporary storage, tagging, and sorting. Interports pose opportunities and challenges for operators involved in freight transport and trade. Mathematically, the authors identify the "interport model" as an extension of the conventional transshipment problem in a hub-and-spokes configuration with the interport treated as a novel kind of hub. The model highlights the advantages that shippers may enjoy in routing their containers from the seaports to their final hinterland destinations via one or several interports. They also discuss an empirical application portraying the intermodal transportation network in the Campania region, Italy. The major seaports of the region are Naples and Salerno; the recently constructed terminal, warehousing and processing facilities at Nola and Marcianise are recognized as interports. A linear programming model minimizes the sum of all container-related logistic costs throughout the entire network, including customs inspection, handling, and storage costs. The solution demonstrates the critical role of adequate customs facilities at the interports, and adequate railway connections between the seaports and the interports.