The paper will try to determinethe effect of road tax and/or road environmental poli-cies on the intermodal split of ports in the Hamburg-Le Havre (HLH) range. We take the case of an EU-wide policy on trucks to reduce road traffic and we explore ascenario using the modified Generic Statistical Information Model (GSIM) model. A 10% EU road tax onall EU member states has ledto a reduction in the market share for the HLH range of ports vis-à-vis non-EU ports. The number of containers is expected to drop by 1 million TEU. The results are relatively less clear-cut: the EU road policy has a positive impact on the market shares of the ports of Amsterdam, Rotterdam and Bremerhaven, and a very negative effect, especially on the ports of Le Havre and Hamburg. As for the intermodal split, the results show that there is a decrease ranging from 1 to 5% of road transport share (with a decrease of 5% for the port of Le Havre, and a decrease of 1% for the port of Bremerhaven) to the benefit of rail and waterway transport. However, substitution is imperfect, so the increases in rail and inland waterway modes of transport do not com-pensate fully for the decrease in the number of containers transported by road.