Accident prevention first of all entails actions based on shared common sense - by acting on alcohol, training and speed, the leve! of safety can be improved. When it becomes harder to obtain safety gains, tools must be developed using statistical approaches and clinical diagnostics to gain a good understanding of the origin of the dysfunctions. System approaches are now recognized as the best scientific reference for analyzing road safety and accidents. Among them, an analytical approach to the system is needed to understand how it works and the origin of dysfunctional situations. The resemblances that appear between different accidents lead to believe that all accidents are not structured in disparate ways, but rather that there are regularities in how they happen. In France, the medical metaphor, often used in road safety, have been extended one step farther and allow to speak of road pathologies while defining prototypical traffic accident scenarios. This approach used in France is the result of different circumstances such as the decentralization and territorialization of various sectorial policies. It is said to be a guarantee of a real adaptation of safety actions to the problems that are actually posed.
