Vehicles Safety Distance on Freeway

The rear-end collision is a main type of traffic accidents of freeway, and the distance between vehicles is a main factor. By analysis of driver's reaction characteristics and factors such as age, gender, speed, drug or alcohol; and combining brake system structure and deceleration process of vehicles, and friction coefficient of road surface, this paper attempts to model the safety distance between vehicles. On the base of analyzing and quantization the factors which affect safety distance, authors calculate the value of safety distance between vehicles. It is found that if the vehicle-gap ranges from relative safety distance to absolute safety distance, the rear-end collision accident can be avoided; and the velocity difference of vehicles is a key factor of the frequent and number of traffic accidents.