Study On Scheme And Alignment Of Helix Line Development In Mountain Highway

With the development of social and economic, highway extends to the mountain depth. When using natural development unable to overcome the elevation difference between the control points, Helix line development begins to receive attention because it has better line conditions than back development and the potential of meet mountain highway alignment. But the application of helix line development in mountain highway is still in the exploratory stage, in the mountain highway route selection, it needs for in-depth study in the use of helix line development and its technical indicators to protect traffic safety.This paper firstly defines the concept of Helix line development, concludes its features and favorable terrain. And based on the special natural and route characteristics of helix line development in mountain highway, used the idea of life cycle cost, it builds a relativly program evaluation system which is suitable for special natural conditions of helix line development, demonstrates its rationality in mountains highway from the technical, safety, economic and environmental.Secondly, according to the highway helix line development characteristics, this paper works out the design indicators considering the inside and outside of the tunnel. These indicators have guiding significance in the helix line development. Moreover, on the basis of determining highway helix line development indicators, this paper studies its design principles, method of alignment design linear, proposes some creative suggestions to the problems in helix development design.Finally, according to the characteristics of helix line development, this paper studies researches the results of line safety evaluation at home and abroad, refined the evaluation methods in the "Guidelines for Safety Audit of Highway", complements its insufficiency. Then it puts forward the evaluation method based on the operation speed, the long vertical slope and the tunnel section, enables the evaluation method based on the operation speed to be suitable for the helix development, and enhances the security of it.