Study On The Safety Of Highway Horizontal Alignment Index And Its Combination

The highway plane alignment is the key factor of the highway alignment.There is an inseparable relationship between plane alignment and traffic safety.Therefore,the safety study of plane alignment is indispensable to enhance the level of highway traffic safety.Based on the plane alignment data and traffic accident data collected and sorted out in Zhejiang Province,this paper studies the safety of the plane alignment index and its combination of expressway from the aspects of human,vehicle and road.It mainly discusses the plane alignment index of expressway(line length,radius of plane curve,length and its deviation angle,length of transition curve,parameters of gyration line).As well as the safety of the plane alignment combination(the ratio of adjacent radius of S-shaped curve,the ratio of basic curve cycloid to length of circular curve),the relationship model between the line length,radius of plane curve,length and its deviation angle,length of transition curve,parameters of gyration line and their combination and accident rate is established,and the specific impact of the above mentioned plane alignment indexes and their combination on traffic safety is discussed and the relationship curve is drawn.The plane alignment combination focuses on the safety of the ratio of adjacent radius of S-shaped curve and the ratio of cycloid of basic curve to length of circular curve.The change characteristics of traffic accidents under different S-shaped curve adjacent radius ratios,basic curve cyclotron and circular curve length ratios are studied,and the relationship models of Sshaped curve adjacent radius ratios,basic curve cyclotron to circular curve length ratios and accident rates are established.The accident data are processed with SPSS software,and the ratio of adjacent radius of S-shaped curve and basic curve cycles are drawn.The relationship curve between the length ratio of the spiral curve to the circular curve and the accident rate.The above research results on the safety of plane alignment index and its combination will be of guiding significance to the plane safety design of expressway.The grey clustering method is used to evaluate the safety of each horizontal alignment combination section,and the discriminant model of the relationship between the horizontal alignment combination section and traffic safety is established.According to the different severity of highway accident,the method of distinguishing the safety of different linear combination is given.With the help of the research results of the relationship between horizontal alignment combination and traffic safety,this paper puts forward the safety improvement safeguard measures of the bad horizontal alignment combination section after discrimination,mainly including safety fence,traffic signs,traffic markings,isolation facilities,anti-glare facilities and sight guidance facilities and so on,which provides a certain reference for the safety design and safety guarantee of expressway.