[en] Transportation of goods contributes to the economic development of societies but it generates negative impacts on its environment called negative externalities. In its White Paper on Transport, the European Commission encourages the flow transfer from road to more environmentally friendly modes like rail or inland waterways (IWW). This objective can be reached by the development of intermodal transport.
A literature review on transport externalities and their valorization methods highlights the small number of studies related to the general modeling of transport externalities through dedicated mathematical formulas. However, the latter are important for identifying the key parameters that influence transport competitiveness in terms of externalities. This is demonstrated by analyzing two external cost functions for road and rail. The location of intermodal terminals stands out from the environmental perspective as one of the most important competitiveness factors of intermodal transport regarding road.
An innovative mathematical model for the location of terminals and allocation of flows between road and intermodal rail and IWW transport is developed. The model is based on a bi-objective formulation which evaluates the trade-offs between transport operational costs and CO2 emissions. Economies of scale of intermodal transport are integrated. The model is applied to the Belgian network. Results indicate that terminal locations are relatively stable, whatever the optimized economic or environmental objective. The type of terminal located changes according to the followed strategy. Minimizing CO2 emissions leads to an increased use of intermodal transport.
The impact of transport on air pollution is also evaluated. On the Belgian case, an economic optimization of transport operational costs is compared to an environmental optimization of transport air pollution external costs. The intervention of public authorities through a taxation policy for trucks is also studied. Results show that the introduction of road taxes leads to a more intensive use of intermodal transport than in the absence of taxes. The maximum intermodal market share is observed when air pollution external costs are minimized.
Finally, a new model which considers other intermodal chains than the traditional “road-rail/IWW-road” modeling is applied on experimental data at the European level. The model allows to choose between any direct transport by one mode (road, rail or IWW), and any intermodal transport of up to three modes. Results indicate that several connections may benefit from the use of other combinations of modes than the “road-rail/IWW-road” combination.
