Assessment of external costs for transport project evaluation: Guidelines in some European countries

Many studies have been developed in the last twenty years about the external costs generated by transport system. To standardize methodologies and assessment procedures to be used in the evaluation of the projects, some European countries recently have adopted specific guidelines that differ from each other in some aspects even sensibly. This paper presents a critical analysis of the British, Italian and German guidelines and is aimed at cataloguing the external cost types regarded and the assessment methods indicated as well as to highlight the differences of the results, in terms of applicability and reliability. The goal is to contribute to a European standardization process that would lead to the drafting of guidelines suited for all EU countries.