Research On Highway Alignment Safety Design Theory And Method Under Great-danger Sections

Highway traffic safety has a close relation with road condition, especially the linear conditions. The route which meeting the driving expectstion that contains continuous and smooth linearis, clear direction and sufficient sight distance is the basic guarantee of vehicle safety driving. The purpose of this paper is to find out the great-danger sections and investigate the theory and method of highway alignment safety design, based on analysis of the effect of road linear on road safety.This paper studies the risk sections and the theory of road linear safety design. The method of highway alignment safety design is also discussed in the newly built and the renovated roads. In addition, few management suggestions on road alignment safety design are put forward. The main research results are as follows:Firstly, through analyzing the statistical feature of the traffic accident, the paper studied the relationship between road alignment and traffic safety, and clarified the connotations and the linear characteristics of the great-danger road sections. The characteristics include poor coordination of driving speed, small radius but huge superelevation, steep longitudinal gradient, deficiency of driving sight distance and so on.Secondly, from the composition and the combination of the highway horizontal alignment, the condition of keeping the linear continuity was inquired. Furthermore, the design principle of satisfying the linear safety was discussed, including the highway driving sight distance, superelevation, the longitudinal gradient, and the synthetic slope selection. Meanwhile, the article put forward not only the method to design the newly built road alignment based on virtual scene technology, but also the method of the reconstruction road alignment safety design based on cubic spline curve fitting.For the newly-built roads:with the aid of virtual scene technology of computer, road reconnaissance design system was developed which can carry on the safety examination for each indicator of the linear design (e.g., curve radius, gradient, superelevation, driving sight distance, etc.). This can make the scene road and the virtual linear into a combination, check the rationality of the design index and the safety of the alignment design, identify high-risk road sections, and provide methods and means for the immediate inspection and real-time modification of the design results.For reconstruct and extended roads:the paper researched the characteristics of four kinds of curve fitting method which contained Lagrange interpolation method, piecewise interpolation method, least square method and spline curve method, proposed the method of selecting the linear parameter based on cubic spline curve fitting and MATLAB software, analyzed the determining basis of the linear design parameters and the influencing factors of fitting accuracy. By applying the fitting technology in practice, put forward the method of selecting the linear parameter and revising suggestions under great-danger roads.Furthermore, according to high correlation between the road accidents and the design of the cross-sectional superelevation, the accident reasons of the S-shaped curve were analyzed. Also, the characteristics of the S-shaped curve were expounded using the whole section superelevation method. At the meanwhile, this paper proposed the basic principle of superelevation transition design of S-shaped curve and the calculating method of superelevation of characteristics cross-sections.Finally, the rationalization proposals of linear safety design were put forward, from the aspects of the selection of main parameters of the linear, roadside alignment design and road design management, etc.This paper brings forth the judgment basis for high-risk roads, by discussing the relationship between road alignment and traffic safety. Then, taking the newly-built and reconstruct and extended roads as the object, the method of highway alignment safety design was explored, using the virtual scene technology and alignment fitting technology. At last, the whole section superelevation method of S-shaped curve design was proposed. The conclusions of this paper, have an important role for promoting the rationality and legitimacy of alignment design indexes and the safety of road alignment, and are useful supplements for highway alignment design theory.