Evaluation on roadside safety degree based on grey theory

The issue of roadside safety is significant in China, especially for mountainous rural two-lane highway. Now there are no systematic methods and effective tools to evaluate the roadside safety degree (RSD) in China. In order to help engineers to make an informed decision or take the most effective measures in highway roadside safety improvement program, the author attempt to put forwards a roadside safety degree evaluation method based on the theory of grey clustering. The method that author offered integrate four categories factors, namely, geometry alignment, traffic volume, history crashes and roadside features. More than ten variables are adopted in the evaluation model. This method can quantify roadside safety performance in terms of level of RSD degree. In this paper, RSD is divided into I, II, III and IV four levels. The higher the level is, the worse the roadside safety performance is. The author introduced this method into Highway Safety-Enhancement Project (HSEP) launched by Ministry of Communications in 2003. In practice, this method revealed favorable feasibility. Additionally, the author has developed an auxiliary computer program (Roadside Safety Degree Evaluation Program-RSDEP), because of the complicated calculating process of the method