Study On Highway Alignment Technology Index In Sichuan-Tibet Plateau Gradient Belt

The geographical conditions of gradient land on Sichuan-Tibet Plateau mainlyshowed by the changing of terrain height, the great spectacular landscape isdemonstrated on the transitional areas. Dynamical system of vehicles may capable notto operate normally on roads whose gradient is overly steep caused by the rapidchanging of terrain height, especially on those roads which was designed by thedirection of current standards. Moreover, the project investment is uneconomic and toensure safety on roads is a severe challenge. It is worthy of studying that how toproperly define the appropriate linear indicators, especially the plane and verticalindicators, of high way constructed on this area under the condition that height variesgreatly in connection with high-altitude and low atmospheric pressure.In order to ensure the traffic safety and reduce project investment, thecharacteristics of dynamic performance changes of selected vehicles is researched underthe guidance of Vehicle Dynamics and Car Theory. The research based on the method oftheoretical calculation analysis, calculate the values of design speed corresponding tovarious gradient zones, maximum longitudinal gradient corresponding to each scale ofdesign speed, vertical indicators concluding grade length limitation, and horizontalcurve radius indicators concluding common minimum radius, minimum radius withoutultrahigh, minimum easement and so on. Besides, the grade value of combination ofaverage longitudinal and steep slope which unable to avoid is proposed refer to theconstructed highway in that area.Compare to the current standard, the methods of design speed in this paper is morerefined and more suitable for the special geographical environment of gradient land onSichuan-Tibet Plateau. And unitized alignment indicators which is more refined andmore specific is proposed in connection with each height gradient under the limit ofdesign speed. The results of this paper provide a reference of highway alignmentindicators selected gradient in that area.Transportation technology projects in Sichuan Province“Plateau gradient zoneexpressway alignment with technical indicators and Design Method”provided financialaid in2011.