The Research Of Computer-aided Fitting Technology On Old Highway Plane Curve

With the development of China's social and economic, the demand for road transport growth fast. However, due to China's large population, poor natural resources, especially arable land resources, only rely on the construction of new roads to meet the growing demand of transportation is not feasible. Renovate the existing highway network expansion to enable it to play a better social and economic benefits, has become a good solution for the contradictions between traffic demand growth and the increasing scarcity of resources.For various reasons, the design data of lots existing highways which are much-needed for reconstruction have been lost, make much trouble to the design of reconstruction, with the result that the old road horizontal alignment control of the situation of large error is not effectively improved. A linear key to solve this problem is resumption the missing design data of the roads.This paper is based on scientific research projects " The Research of Computer-aided Fitting Technology on Old Highway Plane Curve ",in Hunan Province , in 2007, combined with the project of highway G321 reconstruction to carry out the research.The reasearch was based on highway design theory, computer program design theory, combined with the mid-point coordinates of old highway pavement , divid the coordinates into three kinds: coordinates of line, coordinates of circular curve and uncertainty coordinates,Use the Least-squares method to fitting the straight-line, and then calculate the solution adjacent to the intersection line segments to form a broken line graph. When the intersection points are identified, then use the coordinates of circular curve of the road to establish a number of equations, solving a number of circular curve and calculate the arithmetic mean, to be a circular curve fitting data Use the geometric relationship between circular curve and a straight line, calculate the inside displacement value, and then use the function relationship between inside displacement value and easement curve to calculate the length of easement curve. Amend the result will get the initial value of old highway fitting.With the research on the relationship between the mid-point coordinates of the road and the fitting precision, study shows that: the more points a straight line fitting, fitting a straight line segment in the more uniform distribution, then the higher the accuracy of line segments; circle point curve fitting the more concentrated focus on the location of curve, then the precision of a circular curve higher.