The Analysis Of Expressway Traffic Safety Under Unfavorable Weather Conditions

With the rapid development of the expressway, people face the threat of the traffic accident while enjoying more and more convenient and fast traffic. By analyzing causes of accidents, bad weather was one of the important factors. To control speed and safety distance in bad weather conditions was an effective means of reducing highway accidents.This paper analyzed the characteristics of China's expressway accidents such as people, vehicles, road environment. The reason of traffic accidents in bad weather was that adhesion coefficient between road and tire and visibility are reduced.From the theory of tribology, the mechanism of friction between road and tire, influencing factors and adhesion coefficient implication of water film were analyzed. Expressway traffic safety hazards, speed and safety distance in rainy day were explained.By hydraulics, this paper analyzed tires force under the action of hydrodynamic pressure in rainy day and implication of water film on contact zone of tire and road, and divided it into three regions. The adhesion coefficient in the zone of partially or completely water-skiing was deduced. The critical speed at the state of water-skiing was pointed out.The impact mechanism of rain, snow and fog in expressway under adverse weather conditions were analyzed. On the conditions that vertical grade is not well and adhesion coefficient is reduced, braking distance is less than visibility distance, the maximum speed in adverse weather conditions based on safety distance was derived in order to achieve a win-win transport efficiency and road safety.