Effect of activation timing of automatic braking system on driver behaviors

Automatic braking systems have been studied to prevent rear-end crashes. Commercialization of such system is not so widespread since it is pointed out that drivers´ over-reliance or over-trust on the system by introducing such a system could lead to unsafe driving behavior and crashes. On the other hand, the authors proposed a deceleration control method of the collision avoidance system based on the driver´s perceptual risk of collision. The system has the advantage to generate deceleration profile automatically even when the braking timing of the system is changed. In this paper, effect of the braking timing of the system on the driver´s behavioral changes that may reflect over-trust on the system will be investigated. The driving simulator experiments will show that the braking timing close to the driver´s timing might cause smaller THW in the following situation and smaller TTC at emergency situations. In addition, it will be shown that the over-trust may be prevented by making the braking timing will be delayed than the driver´s timing.