Countermeasures for traffic accidents due to road conditions in China

As the postulate of traffic infrastructures and vehicles, the effect of road conditions to accidents should be given much attention to. With large numbers of actual traffic accidents of Shenda Freeway, Liaoning Province and Harbin City in China, the parameters and effect on accidents of horizontal alignment, vertical alignment, cross section and intersection are studied systematically, and the disciplinary analysis of the effect is presented. The critical value and the reasonable range of curve radius and angle of deflection are put forward in view of road safety. The safe grade value and the proposed critical grade are raised in vertical alignment design. The effect which number of lanes, type of cross section, height and gradient of subgrade influence traffic accidents are analyzed deeply, therefore safety influence factor of lanes number (SIFLN) and safety influence factor of cross section type (SIFCST) are presented. The viewpoint is put forward that high subgrade and steep slope are against to traffic safety, which especially common and ignored in high-class highways in China. Furthermore, the causes of traffic accidents are studied in intersections and interchanges, which lead to the presentation of safety influence factor of intersection type (SIFIT). The suggestions of design parameters of the current Design Criteria and the corresponding countermeasures are advanced for safety.