The "Two Points" Method Of Horizontal Alignment Design And Calculation

The rapid development of high-grade highways in recent years has also set a higher standard for the design of road alignments.Traditional methods have been difficult to meet people's needs for economy,aesthetics,and coordination.It is very necessary to further study the road route design method.This paper proposes a "two points" method for the calculation of road alignments.A variety of linear combinations can be determined based on the starting point parameters and end point parameters(symmetrical basic curve,asymmetrical basic curve,S-curve,back-curve,oval curve," clothoid + circle " curve).When designing routes sequentially,the end of the previous segment should be the starting point of the new laying segment,indicating that the parameters related to the starting point of the new route are known.The "two points" method is based on the above rules.Only the end point parameters need to be drawn to determine the required planar linear shape.The "two points" method is mainly used to select one or several unknown parameters from the to-be-designed curve as the search parameters in the method,and the corresponding search range and search step length are given,combining the geometric characteristics of each linear combination.In the calculation of the planar linear design,the parameters of the flat curve used for the search are also different for different plane linear combinations.the symmetric basic curve can be selected as the search parameter by the length of the gyration line or the ratio of the length of the circular curve to the length of the gyration line.Asymmetrical basic curve can use round curve radius as search parameter.S-curve combined with basic curve parameter calculation method.The back curve can use the length of the gyration or the ratio of the length of the curve and the length of the gyro as the search parameter.The length of the first round curve was selected as the search parameter for the oval curve.The radius of circular curve can be selected as the search parameter for the curve of "cycloid + circular curve".Using the general parameters of plane parameters,a range of feasible solutions can be obtained within the search range.In order to improve the effectiveness of the design,the "two points" method gives a corresponding optimization method for each type of linear combination,and can automatically select the optimal solution.Finally,specific examples are given for each linear combination,the corresponding parameter calculation table and the preferred results are obtained and plotted as a plan view.From the research results,this method can obtain multiple feasible solutions of the symmetric basic curve,asymmetric basic curve,S-curve,back-curve,oval curve," clothoid + circle " type curve respectively through "two points".