The Study On The Placing Of Chevron Alignment Sign On High Level Road In Mountain Areas

Traffic accident has been a serious social problem, with the increasing use of vehicles. It not only makes great casualties, but also causes enormous economic losses. The happening of every traffic accident is due to the destruction of the coordinated function system composed by men, vehicles and road. The relationship between the traffic accident and the road feature is even tighter in high grade road in mountain areas.Due to limited factors such as terrain , geological condition .climate ,the lower designed standard, the radius of curve lane, the gradient of vertical slope as well as the condition of the road surface ,it's hard for the driver to drive fast, safely and comfortably in the high grade road in mountain area. In order to inform the drivers in advance to take measures to adopt to the change of the lineless, it is important to set traffic sign, especially the chevron alignment sign in the high grade road in mountain areas.Applying the method of tangential protrusion in distance of road metrical science, this paper has studied the distribution of chevron alignment sigh in each kind of curve line. This paper makes a deduction on the distribution of circle curve line: we have the curve central point of the central road line as the separating point, which cut the curve line into two parts, and each part was expressed by an equation respectively. As there is some distance between the central curve line and two side-line of the road, we must move these two central curve equation outside parallely. The starting point of each equation should be the same. The line of sight and visual angle of driver can also be expressed by equations. By combining these four equations, we get the key of these equations, and that is the distribution place of chevron alignment sigh. Then we have a discussion on the key according to different conditions. This distribution method can also be used in the road comprising adjustment curve line. In the end, the author put this theory into the practice and made an intensive description on how to set the chevron alignment sign on the roads which include adjustment curve line.