Research On Improving The Roadside Safety Facilities Of Low-grade Roads In Mountainous Areas Based On The Cost-benefit

China is a mountainous country,which determines the existence of a mass of mountainous roads.According to statistics,China’s low grade mountainous roads mileage account for total mileage by more than 85%,low technical grade and poor route line and little roadside facilities are popular in low grade mountainous roads,it makes high accident rate and massive loss,so that optimal design low grade mountainous roads ‘roadside become a urgent problem to be resolved.Firstly,the paper points out the main problems of our country’s in roads roadside safety design,clearing up low grade mountainous roads roadside forms.Colliding passengers and colliding motionless vehicle and jumping into side ditches and colliding avenue tress occupy total by more than 65%,which is the main accident form.Otherwise,falling into high bridges and cliffs hardly happened that we should pay attention to it because of leading to mass death and casualty.Analyzing the impaction of the human being & the vehicle & the road conditions & the road-side conditions and the poor weather on road-side accident by the theory of causing accident.Introducing detailedly the theory of how to using obscure method for identification to discern the accidental black spots.And grading the danger level from the accidental black spots.The paper introduces the seven of common road-side safety facilities design methods combining with the practical situation of mountain low grade roads.And calculate each road-side safety facilities design method basing on highway engineering quota calculation method.Using funds equivalent theory to calculate road-side safety facilities design methods’ operational and maintenance cost.Re-scaling road-side accident by the number of injuries and deaths people and property loss which reference to 《Road traffic accident treatment method》publishing in 1992.Then the paper analyzes systematically the total economic losses.In order to measure the road-side safety facilities plan safety benefit,introducing the road-side accident severity index indicator.And calculating varying degrees accident’s losses.The paper use implementing road-side safety facilities design method that reduced the losses as benefit of safety.It means that monetize safety benefits.Finally,The paper points out that road-side accident severity index indicator as a link between cost and security benefits.it introduce the cost-benefit method optimal decision of roadside safety design,deciding road-side safety facilities plan by present index which taking engineering cost into.The paper established the method which optimize decision-making low-grade mountainous road based on cost-benefit analysis methods.And verified the rationalization of the conclusion through The Fifth phase Home city road of WuShan,roadside safety optimization design case.