Multimodal Freight Transportation Network Design Problem for Reduction of Greenhouse Gas Emissions

At the strategic level, multimodal freight network design problems are limited in that they reflect the costs and constraints associated with emissions. The network design problem (NDP) addressed in this study determines investment alternatives for minimizing total system cost, including costs related to greenhouse gas (GHG) emissions, while satisfying the emissions constraint. The NDP can accommodate improvement alternatives in transfer terminals as well as in road and railroad links. In this study, mode-specific travel time functions were used to represent the differences between the modes explicitly, even for the transfer facility. Emission factors were calculated by link travel speed and level of facilities. The empirical application to a container freight network from the Port of Pusan in southeastern South Korea showed the optimal investment strategy for meeting emissions reduction policy objectives. The conclusion is that investment should concentrate on railroad and terminal facilities to induce modal shift. In contrast, investment in congested roads might be a better option for corridors in which the level of railroad service is low and short-distance freight demands are dominant. These results indicate that the proposed network design problem can provide the appropriate investment strategy for reducing GHG emissions and therefore can be a useful approach with regard to GHG emissions reduction policy.