Freight transportation planning considering carbon emissions and in-transit holding costs: a capacitated multi-commodity network flow model

To mitigate climate relevant air emissions from freight transportation, policy makers stimulate the application of intermodal freight transport chains. The evaluation and selection of intermodal routes based on the key objectives, i.e., greenhouse gas emission, transportation cost and transit time improvements, are the main challenges in the design of intermodal networks. It is the aim of this paper to provide decision support in intermodal freight transportation planning concerning route and carrier choice in transport service design and the assessment of emission abatement potentials. Core of this approach is a capacitated multi-commodity network flow model considering multiple criteria and in-transit inventory. Thereby two processes are modeled, i.e., the transport and transshipment of full truckloads (FTL), to define the material flow of goods through the network. The objective function of the developed network flow model minimizes the number of transported and transshipped FTL assessed by the weighted and normalized criteria (i.e., CO2-equivalents, cost, time) taking into account tied in-transit capital and the distance traveled. Thereby, the model regards carrier and terminal capacities, the option to transfer or either shift the mode and/or change the carrier at predefined terminal transshipment points. The model is incorporated in a decision support system and applied in an example application with industry data from an automotive supplier to demonstrate its application potentials. Within the application among others the potential benefits of the developed optimization model in comparison to a status quo are analyzed. Different criteria weightings and the influence of various levels of in-transit holding costs are investigated. In addition, the introduction of new transportation means such as the Eurocombi is assessed.