Efficient model and heuristic for the intermodal terminal location problem

A multimodal transportation system transports freight using at least two transportation modes. Among available transportation modes, intermodal freight transportation transports freight in an intermodal container or conveyance without handling the freight itself when changing modes. The locations of intermodal terminals constitute the foundation of an intermodal transportation network. The intermodal terminal location problem therefore aims to determine terminal locations and routes within a transportation network in order to minimize the total transportation and operation costs through collaborations of unimodal road transport and intermodal transport chains. Relevant research includes that of Arnold et al., who first presented mathematical programming models for the problem. Sörensen et al. recently proposed a standard model for the same problem. However, these models are complex and time consuming. Some decision variables and constraints of Sörensen et al.׳s model are proven to be redundant. A modified mixed integer programming model is then developed to increase computation efficiency. The modified model finds more optimal solutions to the benchmark problems than current approaches do, within a reasonable time. Furthermore, two matheuristics are presented to solve the problem more efficiently while obtaining near optimal solutions.