Study On The Safety & Security Of Freeway In Mountainous Area Under Rainy COndition

Nowadays traffic accident caused by rainy days has been put a new premium on all over the world. The traffic accidents in rainy days are always a series of chain contingency. For example, rear-end collision is not a one car accident, but many cars will be embroiled. The accidents caused by rainy days are more dangerous, which will cause higher casualties and economic loss.This study is based on the knowledge of Expressway Engineering, Traffic Engineering, Meteorology and Statistics, relying on the beltway of Chongqing, targeted to carry out the accident causes of freeway and guarantee technology research based on safety in rainy days.First of all, by collecting the information on road conditions, traffic flow and accident date of a freeway in Chongqing, analyzes the characteristics of wet weather accidents with the method of statistics . Rain accident vehicle dominated by small cars, single vehicle take higher percentage of rain accidents, trailing collision and hit fixtures are the main accident form, the accident risk on curve segments is larger than straight line. Observe the rain accidents distribution along the freeway, and analyze the characteristics of the distribution of the rain accidents. The ratio of rain accident on the curve is greater than the proportion on straight-line segment, of which 70% of accidents on the bend in circular curve segment, 30% occurred in the superelevation transition, and to analyze its causes.Second, through field research and experiments, analyzes the causes of rainy days'accidents when wet pavement and surface water. By analyzing the relationship between lateral acceleration and the rainy day accident rates, proposed use the suitability of lateral acceleration of the rainy days to evaluate the driving safety.In the performance analysis of road surface drainage, by analyzing the by the geometric characteristics of the superelevation transitions, flow paths of the superelevation transitions and water film thickness characteristics on superelevation transitions, in combination with the mechanical model of surface runoff to assess the drainage characteristics. Then, proposed the drainage improvement program of the superelevation transitions, and the programs were evaluated.At last, water film thickness and hydroplaning speed calculation software was edited by Java programming language, and actually calculate the general limit value of the hydroplaning speed and water film thickness under different rainfall conditions.