The main factor of over-risk related to road infrastructure is fixed roadside obstacles. Due to their high stiffness, they represent a major danger in the event of loss of car control.

In France, on the road network outside of urban areas, about one third of the car fatalities recorded in 1990 were in crashes against fixed objects, and involved about 1600 fatalities. As far as trees alone are concerned, it should be emphasized that 900 fatalities are related to this kind of obstacle, mostly for lines of trees along the roadside.

Impact characteristics will be given for primary safety factors (circumstances, road conditions, driver state, etc.) and also for secondary safety aspects (impact types, violence of impacts, intrusion frequency, etc.).

Expected benefits (saved lives) from road infrastructure improvements by using guardrails, principally in front of trees, are studied on the basis of extensive and well-documented fatal crash police records established by the police force network over 6 months for all of France.