Cost-Benefit Analysis (CBA) is a tool used to evaluate the potential socio-economic impact of public investment choices. In many countries, particularly in France, this tool is used to support decision-making related to transportation infrastructure. In the context of questionable budgetary arbitrations, taking the multiple effects of the different choices into account makes choosing among transport infrastructure investments is a two-fold problem. On the one hand, public decision-makers have limited resources that they must use in the best way possible. On the other hand, when choosing among alternative investment projects, the decision-makers reveal the priority they have assigned to the different stakes, and these priorities must be perceived as legitimate. The French case illustrates the difficulty of striking the right balance between the expert knowledge produced by CBA methods and what is induced by the participation of various stakeholders to the decision making process. Based on a study of how French institutions make use of the CBA method, this paper aims at examining how the use of cost-benefit analysis (CBA) interacts with the practice of public debate and stakeholder participation in France today.
