目前在有关文献中,表达铁路曲线各个特征诸如曲率二次导数K″、曲率一次导数K′、曲率K、倾斜角φ和渐伸线长度ε的表达式,缺乏一个全面的综合性的描述。在这种情况下,若要解决某一运算问题时,常由于不恰当地选用了直角座标系,或是图式选择不当,或是没有综合考虑问题,致使推导显得繁杂。因此,笔者在前人成就的基础上归纳整理,取自然座 At present, in the related literature, there is no comprehensive and comprehensive description of the expression of each characteristic of the railway curve such as the second derivative of curvature K ", the first derivative of curvature K ’, the curvature K, the inclination angle φ and the length of involute line ε. In this case, to solve a certain arithmetic problem, often due to improper selection of the Cartesian coordinate system, or the schema inappropriate choice, or did not take into account the problem, resulting in derivation is complicated.Therefore, I was On the basis of achievements made by predecessors, they should be sorted out and naturally taken