Implications of Risk Perception under Assumption of Rational Driver Behavior

This paper presents research on driver risk perception and its connection with driver selection of speed and with highway safety. The paper also supports the theory of rational behavior. The implications of driver risk perception on the speed–safety relationship and on use of speed as a surrogate measure of safety are discussed. The authors distinguish two distinct speed–safety relationships: one under fixed roadway conditions and the second under changing roadway conditions. The paper demonstrates that a population of drivers can perceive risk that is consistent with the actual risk of crash, and that assumption of rational behavior is useful in explaining why roads with higher speeds are perceived as, and tend to be, less risky. Road improvements are used by drivers mainly to improve mobility and, to a lesser extent, their road safety. Speed can be used as a surrogate measure of safety if the change in speed has been accomplished without changing the road geometry. Otherwise, the safety effect of the improvement is not clear and should be evaluated directly using crash-based statistics.