超高-道路几何设计.ppt

Members： 2011.4.13 Superelevation 超高 Content Domestic design method of superelevation Foreign design method of superelevation Comparison Question：  某双车道公路，设计车速为60km/h，交点桩号为K87+952.00，偏角a右=26o37’,圆曲线半径R=160m, 试：     （1） 按中国相关标准规范，作此平曲线的超高加宽设计（超高过渡方式为绕路中线旋转）；     （2）按附件“Superelevation.ppt”（美国绿皮书方法）有关双车道超高设置的方法，分别对设缓和曲线（transition curve or spiral）和不设缓和曲线时的超高加宽进行计算。（超高、加宽取值同上；超高过渡方式仍为绕路中线旋转） Domestic The choosing of parameters: Determine Ls: Comfortable: 2. Moderate p: 3. Enough travel time: Finally Ls= 50m Ls(min)=0.0214v3/Ras (m) Ls=Lc Ls(min)=v/1.2 (m) Domestic The choosing of parameters: The determination of Ls The stake number of ZH： K87+889.11 Choose: Domestic Results: Domestic Results: Foreign（with transition curve） Foreign（with transition curve） Results: Foreign（with transition curve）有 Foreign（without transition curve） Foreign（without transition curve） ih=0.04 iG=0.02 iJ=0.04 Foreign（without transition curve） Results: Foreign（without transition curve） Comparison Compared with the domestic norms, when the transition curve is used, the rotation of superelevation starts from straight line, which can ensure that the transition curve’s length is enough to meet the superelevation. When there is no transition curve, the AASHTO does not make the whole superelevation in the straight line. The AASHTO provides a table to choose appropriate ratio. Thank you