Abstract: To explore ACC's impact on driving safety, actual road driving tests were carried out, Chinese typical road scenes were acquired, then these scenes were rebuilt in a driving simulator. Driving tests were made on a driving simulator under with/without ACC conditions, so as to contrastively analyze ACC's performance, and detect drivers' emergency reaction, by analyzing TTC of drivers belonging different characteristic groups. The results show that ACC can handle most types of road situations, that when faced with dangerous situations that ACC can't handle, all kinds of drivers' emergency reaction with ACC driving is slower than that in manual driving, that female, old drivers or drivers with little ACC knowledge are more vulnerable to ACC's adverse impact, and that safety of ACC driving is dependent on driver's ACC knowledge.

Key words: adaptive cruise control(ACC)system, driving safety, simulated driving, time to collision (TTC), characteristic of driver