Abstract
Infrastructure quality is an essential element in road safety as it is usually admitted that one third of accidents is due to a faulty design, for example of alignment, approaches, cross and longitudinal sections. Collective awareness is needed of course, together with a new approach: drivers and their behaviour must be taken into account at every step of thought and working our of solutions to be applied. Then come diagnosis methods to detect factors conducive to accidents. In France, an interesting identification method has been developed in case of serious accidents with a programme called REACT.