B型喇叭式立交环圈出口匝道运行速度过渡段长度研究

Reserach on the Operating Speed Transition Section Length at Ring off-ramp of B-type Trumpet Interchange

为确定车辆在B型喇叭式立交环圈出口匝道满足安全行驶需求的运行速度过渡段最小长度,分别建立了满足超高过渡需求、车辆变速行驶需求、横向加速度变化率适中等要求下的运行速度过渡段长度计算模型。采用UMRR开普勒链式雷达测速仪,实测不同主线设计速度下环圈出口分流鼻运行速度,结合SPSS软件分析,得到分流鼻运行速度。基于运行速度过渡段长度计算模型和典型参数的分析论证,得到满足不同需求的运行速度过渡段最小长度。结果表明:车辆变速行驶需求是B型喇叭式立交环圈出口匝道运行速度过渡段长度的主要控制因素;并基于满足车辆安全行驶需求,提出了运行速度过渡段长度最小建议值及纵坡修正系数。

In order to determine the minimum lengths of the operating speed transition section which meet the safe driving demand of vehicles at ring off-ramp of B-type trumpet interchange,the calculation models of the operating speed transition section length were set up respectively to meet the requirements of ultra-high transition,speed-changing driving and moderate lateral acceleration change rate.Through UMRR Kepler chain radar tachometer,the operating speeds at the diverging gore nose of the ring off-ramp were measured under different main line design speeds,and with SPSS software,the operating speed representative values at the diverging gore nose were obtained.Based on the length calculation models of the operating speed transition section and the analysis of the typical parameters,the minimum lengths of the operating speed transition section were obtained to meet different requirements.The results show that vehicle variable speed driving demand is the main control factor for the length of the transition section at the ring off-ramp of B-type trumpet interchange;and based on the safe driving demand of the vehicles,the minimum recommended values where proposed,as well as the correction coefficients of longitudinal slopes.