Study On The Typical Truck Running Safety Tests Along51km-Distance Downhill On Yaxi Expressway

In Sichuan province, Yaxi highway is the important part of the highway from Beijingto Kunming (G5), which is located in Liangshan Prefecture, Ya’an City. Because locatedin the Qinghai-tibet Plateau and Sichuan Basin combine belt, complex topographic andgeologic conditions along the line,the whole journey go through six times crosslinealtogether,form three long length continuous longitudinal slope, amomg the journeycontinuous longitudinal slope of the Tuowu Mountain’s north slope crossline reach51kmlong, average longitudinal grade is2.97%, and mileage above the snow line is16.7km,which is China’s first long downhill. In addition to the driving safety issues caused by thelong downhill itself factors, sections are also affected by ice, snow, rain, fog and otherinclement weather conditions, these will bring new challenges to the operation safety afteropening.Around the Yaxi mountainous area highway51km-distance downhill highway truckdriving safety problem, this research systematically studies highway truck safe operationcondition of China southwest mountainous area, the difference among truck brake safetyperformance bench test,field test and real road test, the51km-distance downhill in Yaxihighway truck driving safety testing method, carry out51km-distance downhill drivingsafety test of the two axis, three axis, six axis typical trucks, and synchronously take thelong downhill driver visual characteristics. Finally, study and analyse the various testresults, apply the forming research results to traffic safety engineering and real operationsmanagement before opening the highway. The main content of study are:(1)Study the mountainous area highway long downhill about truck safety operation ofthe status quo in recent years, including: our country and sichuan province highway truckoperation conditions, accident characteristics and driving safety factors analysis in recentyears； Mountainous area highway truck safety technical conditions and truck auxiliarydriving brake systematic appling situation survey；Mountainous area highway professionaldriver safety related factors investigation and analysis.(2)Study the difference among truck braking performance bench test, field test androad test,including: the feature and shortage of truck brake performance test； the featureand shortage of truck brake performance field test；The feature and advantage of the trucksactual vehicle road test.(3)Study the schematic design for trucks real vehicle long downhill performance testing,including: systematic integration and development program of test equipment；match the installation and commissioning of the testing system； experiment content andmethod design of the long downhill section； Test data acquisition and results analysismethod.(4)Study Yaxi highway51km-distance downhill trucks about running securityimplementation scheme of real vehicle test, including: the whole testing process scheduling,vehicle use, coordination of various departments, capital budgeting, risk aversion, andsecond implementation plan, etc.（5）Study Yaxi highway51km-distance downhill truck about analysis method ofrunning safety operation parameter and application scheme of results.The innovation point of this study is mainly reflected in the following aspects:(1) For the first time test running safety of the real vehicle including two axis truck,three-axis truck bicycle, six axle semi-trailer train under standard load and overloadconditions at Yaxi highway,51kilometers long slope sections, and under different workingconditions test the single truck exhaust butterfly valve, Jacobs engine retarder, Voithhydraulic retarder in the long downhill driving auxiliary safety performance, provideempirical basis for different types of auxiliary brake system on the different types of truckmatching scheme in the long downhill road section.(2)Develop and use online truck brake drum temperature real-time monitoring system,monitor the brake drum temperature rising condition in real-time when the truck drivedownhill,in order to determine the easy to get out of control sections in51km-distancedownhill truck； Through the brake drum emergency braking test under cold and hot state,analyse the heat recessionary degree, and take comparative study between the actual testresults and the industry commonly used brake drum thermal recession theory model.(3) Apply driver’s visual information test to51km-distance downhill experimentsynchronously, evaluate signs, marking, signs of the51km-distance downhillsystematically, and optimize according to the experiment results,then the road safetyimprove.(4) Apply real vehicle test results to the highway operation safety engineering timelybefore opening Yaxi highway, effectively improve the long downhill operation safety, andobtain obvious economic and social benefits.