As far as sustainable transport development is concerned, transfer of cargo from road transport to short sea shipping, which, according to the common opinion, generates lower external costs, is one of the objectives of the European Union policy. However, the latest research results indicate that some Ro-Ro vessels and ferries generate higher external costs than road transport. In light of this, benefits resulting from transferring the cargo from road to sea seem to be questionable. The main aim of the article is answering the question whether, and if so, how ferry and Ro-Ro shipping contributes to development of sustainable transport? In order to answer this question, an analysis of ferry and Ro-Ro shipping lines functioning in European transport system has been conducted.

The article presents research results based on an analysis of approx. 900 ferry and Ro-Ro shipping lines considering the length and time of voyage compared to alternative road transport. Usually, the course of sea shipping route does not cover the route of the road transport, and therefore the lengths of both routes frequently considerably differ, which significantly affects the total external costs generated by them. On the basis of the analysis, the shipping lines have been classified according to the criterion of their substitutability to road transport and their role in sustainable transport development.