高等级公路超高渐变率的探讨

Discussion on the Gradient Ratio of Freeway Superelevation

超高设计是曲线路段安全设计的重要环节。超高渐变率作为超高设计的重要组成因素,直接影响超高设计的优劣。通过对《公路路线设计规范》JTG D20-2006中关于超高设计部分规定的研究分析,详细说明了如何选择超高旋转轴位置;提出了一种以旋转角速度来控制排水不畅段落长度的方式,代替超高渐变率最小值的规定;而后分别从车道数与硬路肩两方面分析了其对超高渐变率的影响,得出在现状交通量不断增加、路幅宽度不断增大的情况下,简单采用原定渐变率设计超高是不可取的。

Superelevation design is of great importance to the safety design of curved sections. As one of the important factors,the gradient ratio of superelevation has a direct influence on the quality of superelevation design.By analyzing the regulations about superelevation design on Design Sepcification for Highway Route（ JTG D20-2006）,how to choose the axis of superelevation rotation is explained thoroughly. A method,controlling the length of poor drainage by controlling the rotational angular velocity,is proposed,which can replace the regulation for the minimum value of the gradient ratio of superelevation. Relevant effects are also analyzed through the number of lanes and the hard shoulder respectively,reaching the conclusion that with the increasing traffic volume and width of road,it is not advisable to use the specified value of the gradient ratio of superelevation directly.