Measuring the driver's perception error in the traffic accident risk evaluation

The perception of risk, as the expectation of being involved in a traffic accident, is evaluated mainly in a subjective manner being perceptions as highly individual, and depending on experiences with accidents. However, both individual driver characteristics and driving behaviour entail certain perception errors in the risk level evaluation; as a consequence, drivers are very often not aware of the actual risk they are taking. For this aim, the paper presents a methodology for measuring the driver's perception error in the traffic accidents risk level evaluation based on the comparison between a measure of the risk perception subjectively obtained, and an objective measure obtained from kinematic parameters defining the driving style. Starting from a procedure that describes the relationship between lateral and longitudinal accelerations and speeds, we classified car drivers' behaviour as safe or unsafe. Then, we defined three levels of risk of being involved in a road accident (low, medium, and high risk). The subjective measure of the risk perception is obtained by the judgements of drivers regarding their driving behaviour.