France is reviewing its long-lived socio-economic appraisal of infrastructure projects, and recently a Commission has issued a report on this subject. After a rapid view of its conclusions we focus on some specific points more closely related to the present situation, marked by risk and possible changes in the rate and structure of economic growth, mainly due to environmental and energy constraints. The use of low discount rates together with growing uncertainties on future economic growth and climate change outcomes and counter-measures eagerly calls for research on long term issues. It becomes necessary to define a consistent, long term, strategic vision as an appropriate input for correct project appraisal, based on a set of scenarios. We discuss and illustrate concretely the changes that would be induced in investment choice procedures and CBA practice.