Study On The Safety Evaluation Methods In Mountainous Freeway

With the increasingly traffic safety problems on mountainous freeways, it is veryimportant and significant to research the safety assessment method of mountainous freeways.This paper discusses the appropriate way for mountainous freeways safety assessment fromthree aspects, that is, the vehicle’s operation speed, accident prediction and the relationshipbetween traffic accidents with the road alignment.Both the GSAH (‘Guidelines for Safety Audit of Highway’) and the DCM (DesignConsistency Model) of IHSDM (‘Interactive Highway Safety Design Model’) establish theroad speed prediction model and give the way of assessment of road design consistency. Thepaper analyzes the two different predictive modes and the similarities and differences betweenthem, and then applies to the design consistency evaluation of mountain highway. The resultsshow that: the speed result predicted through the DCM model is superior to that predictedthrough the GSAH model, and the results of design consistency evaluation are different; thetwo kinds of methods can not be effectively used to evaluate mountain highway designconsistency and they are lack of targeted.The CPM, which is used for mountain highway accident prediction, is calibrated. Theresults show that: the prediction results given by the CPM module vary greatly with thefindings, which can not reflect the characteristics of mountain highway accident; then thereasons are analyzed.The paper analyzes the relationship between the common road with the mountainoushighway in the alignment factors. Combined with three evaluation criteria based on the rate ofchange of Horizontal Curve curvature(CCR), the practicality of the two models in mountainhighway is discussed; combined with the ratio of Horizontal Curve radius to the averageradius (CRR)and the ratio of the average longitudinal slope of single Horizontal Curvesections to the average slope according to the number of Horizontal Curve(LSS), the roles oftwo different models as the road alignment factors in the evaluation of mountain highway isresearched. The results show that: road alignment factor plays a small role in mountainhighway safety evaluation, and the applications are not effective.