A Computer Aided Design Method for Oval Curve in Road Route Design

Abstract

The invention relates to a computer-aided design method for oval curves in road route design, which belongs to the technical field of road computer-aided design, and provides a computer-aided design method for oval curves in road route design. The design method of the present invention is based on the isotropic curve that can not directly constitute the complex curve and has short straight lines, or the C-type curve, through selecting the tangent point D on the small garden curve of the isotropic curve and choosing the tangent point on the large garden curve C. The design steps of calculation of intermediate transitional curves and data correction of intermediate transitional curves are drawn according to point-by-point coordinates to complete the oval curve design. The oval curve formed by the design method of the present invention eliminates short straight lines that cannot form complex curves between curves in the same direction, solves the problem of unfavorable line types such as C-shaped curves with zero curvature, and significantly improves the driving safety environment. It can be widely used in the linear design of interchange ramps and the same direction curves of various roads, and the design calculation method is simple and convenient.

Description

Technical field [0001] The invention belongs to the technical field of road computer-aided design, in particular to a method for computer-aided design of oval curves in road route design. Background technique [0002] To form an oval curve, theoretically, it is formed by inserting a transitional curve between two large and small circles, that is, a clothoid curve. There are currently three methods, one is to insert a section of intercepted clothoid curve; the other is to use a transitional circular curve; the third is to Intercept and insert a cubic function curve that meets the requirements. For the first type, the use of intercepting a section of the clothoid curve to form an oval curve is advocated in the design of road routes, but in practice, due to the difference in curvature radius, distance and relative position between two circular curves, it is very difficult to use difficulty. The current design calculation method is in A 2 =L S R 2 On the clothoid curve, int...

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Problems solved by technology

However, through a large number of computational studies, it is shown that the connection of the great circle R at this time 1 and Madoka R 2 The clothoid curves of the two circular curves are not the same clothoid curve as the initially determined clothoid curve. In other words, the clothoid curve segment is used as the intermediate transition curve. Otherwise, the sudden change at the junction of the large circle or the small circle cannot be eliminated; in addition, it is difficult to find a suitable tangent baseline in actual surveying and setting out, and the current route design software cannot handle this problem well. The design and calculation method of the oval curve is possible in theory, but it is almost impossible to use it in the actual route survey and design

In order to eliminate short straight lines between the same direction curves, or C-shaped curves with zero curvature, which are very unfavorable to driving safety, using a transitional circular curve as an alternative is sometimes used, but the disadvantages It is impossible to eliminate the mutation of the radius of curvature, and it often occurs that the difference in the radius of curvature when multiple circular curves are combined with complex curves is greater than 1.5 times

For the third case, the cubic curve is used as the transition curve, which is more complicated, and it is difficult to determine the parameters for actual use. It is difficult to establish an equation that meets the actual needs, so it is hardly used.

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