Relationships between road geometry, drivers' risk perception and speed choice: an experimental study

This paper presents the results of an experimental trial conducted on a population of 64 road users. Test participants drove a vehicle equipped with GPS on an oval racetrack. The GPS system recorded the position and the speed of the vehicle. The objectives of this study were to analyze1) the correlation between risk and the speed perceived by the drivers, 2) the influence of the geometric layout on the perceived risk, 3) the influence of familiarity with the environment on the perceived risk, 4) the analytical perception of the speed. Test participants were recruited to drive on the test track for a total of 18 laps. The population demographics were identified through a questionnaire. Three different scenarios were used during the experimental trials. The scenarios consisted of different driving instructions given to the drivers, namely 1) the adoption of three vehicle speeds indicated qualitatively (low, medium, high) with no real time information to the driver about the speed, 2) the adoption of three speeds indicated quantitatively with no real time information to the driver about the speed, 3) the adoption of three speeds indicated qualitatively (i.e., using a low, medium and high level of safety) with real time information on the speed to the driver. The study permitted us to identify a correlation between risk perception and drivers’ familiarity with the test track. The test also showed the relationship between speed and perceived risk and the relationship between speed and the geometric layout of the racetrack