This paper has been produced as part of the activities of the TRKC (Transport Research Knowledge Centre) project of the Sixth Framework Programme. The role of TRKC, as its predecessor project EXTRaWeb, is to collect, structure, analyse and disseminate transport research results. TRKC provides comprehensive coverage of transport research in EU programmes as well as key research activities at national level within the European Research Area and selected global programmes. The paper is one of the thematic research summaries (TRS). The TRSs aim at providing a synthesis of research results and policy implications from completed projects. Each TRS deals with a theme according to the classification which the TRKC project has adopted. The theme of this TRS is "efficiency of transport systems". The first part of the paper includes a brief analysis of the scope of the theme, and a policy review where the main policy developments at EU level are summarised. The theme "efficiency of transport systems" deals with the minimisation of the resource costs of a given transport system and the maximisation of its performance. Costs considered include those borne by the transport users and those by the transport operators. The relief of congestion and reliability is a significant element in the consideration of efficiency. External costs borne by society at large such as those of accidents and of environmental impacts are not considered as they are tackled within other TRSs.