计算既有铁路曲线坐标法拔距的一种新方法

为克服传统方法计算缓和曲线段拨距时,用弦长代替弧长引起的误差,基于坐标法整正既有铁路曲线的相关原理,提出了利用既有测点沿径向到拨后曲线的距离计算拨距的新方法.按照该方法,推导了测点的拨距及拨后坐标的计算公式,并将其计算结果与传统方法的计算结果进行了比较.结果表明,采用传统的坐标法计算拨距时,缓和曲线越长、半径越小,拨距和拨后正矢误差越大;拨距最大误差为1.3 mm,拨后正矢误差最大值为1.0 mm. 

New Method for Move Distance Calculation with Coordinate Method for Existing Railway Curve

To overcome the error resulted from substituting chord length for arc length in the traditional method to calculate the move distance of a transition curve, based on the theories related to existing railway curve realignment by the coordinate method, a new method to calculate move distance was put forward by using the distance from the existing measurement points to the points on the moved curve in the radial direction. The analytical method was utilized to derive the calculation formulas of move distance and moved coordinates of measure points. The calculation results were compared to those calculated by the traditional method. The results indicate that the traditional coordinate method to calculate move distance has errors, and the errors of the move distance and moved versine increase with increasing of transition curve length and decreasing of its radius. With the traditional method, the maximum errors of the move distance and moved versine reach 1.3 and 1.0 mm, respectively.