Driver behaviour in car-following: a driving simulator study

This paper describes the results of a study performed with the interactive fixed-base driving simulator of the Inter-University Research Center for Road Safety aimed: a) at analyzing the driver behavior in car-following situations in different traffic-flow conditions and b) at providing the first elements to choose the most appropriate threshold value of Time-To-Collision (TTC) in order to discriminate unsafe from safe car-following behaviors. A test alignment 8.5 km long and 4 different traffic scenarios were implemented in the simulator. Thirty-two subjects drove in the simulator. Several values of threshold were used to quantified advanced TTC-based indicators. The results highlighted that: 1) the car-following behavior is significantly affected by the volume-to-capacity ratio; 2) the most efficient threshold values of TTC seem to be 2.5 and 3s. These results should be considered for the development of Collision Avoidance System