Open issues in the practice of cost benefit analysis of transport projects

Cost benefit analysis is the commonly used tool to evaluate transport investments. Despite its diffusion, both the technicalities and the purpose of the analysis differ among countries. This paper focuses on some common issues and lacks still present in the evaluation of transport projects, in the light of the most recent contributions in the literature. We try to clarify two open issues: the treatment of the mode shifting component of induced traffic, the treatment of lost fuel taxes due to mode shift and of generated fare revenues and the evaluation of impacts during construction and maintenance. Moreover the paper describes and discuss the use of some advanced techniques: the use of conversion factors to assess the shadow value for labour costs and public funds, the treatment of wider economic effects, the use of distributive analysis and the use of risk analysis.