On driver´s braking behavior in car following

A new index have been proposed to evaluate danger situation in car following based on the hypothesis that drivers evaluate collision risk for preceding car and decide braking behavior with change of area of a preceding car on the retina. Based on the index, braking behaviors in car following situation is analyzed. Decelerating profile of a test driver is modeled using the proposed index and the gap D based on the experimental results of the test driver with a real car. In addition, the results of laboratory experiments using a driving simulator support the results of the real car experiments. In addition, braking initiation timing of the test driver is characterized as a brake judgment line in the plane of the modified index and gap D and the characterization is applied to analyze change of the braking initiation timing according to the change of road condition.