| With the rapid economic development and social transition of our country,it is necessary for the southwest and northwest underdeveloped regions to realize economic development.At present,the density of China’s road network is increasingly dense.In the northwest and southwest regions,it belongs to the second and third-tier transition zones of our country with high ground difference,topographic relief,mountains and rivers.Therefore,in the mountainous area highway route layout difficult complex,in order to overcome the ground gap and control the longitudinal slope design of quantities tend to be more big,it will be that driver the load of vehicles on the road in order to control the speed not fast and frequent deceleration,the load of vehicle brake drum temperature is too high and the misfunction of brake and may cause one car down,or the malignant accident.In this paper,based on this,combining with the current standard about hedge lanes and research status at home and abroad,with the actual type and engineering common and often used on slope safety lane as the research object,it will make comprehensive research of the geometric design indexes.Truck-escape ramp of safety design,specifications and standards did not give a clear design index.At the same time,related research is also from a study on the design parameters and indexes.It leads to tha lane safety index parameter design can’t meet the emergency safety when the load of vehicle brake failure.Set up in this paper,from the position of the truck-escape ramp,plane,profile and cross section study.For the position of the hedge lanes setting use lateral stability safety lane by changing the maximum design speed,considering the different types of vehicles in our country,combining with the actual project traffic to select representative models.Meanwhile,according to hedge lanes instance project to hedge lane position setting process is given.Based on a large collection of relevant data and documents,it controls lanes of plane,profile and cross section design index by calculating and detailing discussion on the research from the main line type(straight,turn left and right curve)analysis to hedge lane outflow.Angle of the size,it will propose the length of the ramp,braking lane values,the setting calculation of auxiliary lane length values.Profile reference related literature,the analysis of the main line of hedge lanes of transition,vertical acceleration,3s responses from stroke and visibility at night,it is considered through three aspects,calculation and gives the approach road “concave” in the transitional period of vertical curve length and the average,minimum radius values.Hedging lane lane cross-sectional index by the main line to the braking process of each section to analysis: the gradual,ramp and brake the cross section width of lanes,lane and braking of transverse slope and drainage,etc.In this article,the geometrical design elements of the safety lane are studied in this paper.The conclusion is of guiding significance and practical value for the establishment and the secure designing-lane of highway in mountainous areas in China. |
