山地城市螺旋匝道驾驶仿真与关键设计指标

山地城市受道路资源等因素的制约，常将螺旋匝道作为衔接两侧道路高差的方案。由于目前缺乏针对螺旋匝道的设计标准，导致螺旋匝道在设计时往往沿用环形匝道甚至支路的线形标准。选择重庆市主城区的7个螺旋匝道开展自然驾驶实验，并通过Carsim仿真软件建立道路环境模型，分析比较导致车辆轨迹偏移的关键影响因素。研究结果表明：在利用Carsim进行驾驶员仿真模型建立时，采用闭环控制模式仿真结果可信度较高；当仿真运行速度超过实测运行速度62.5%以上时才会出现轨迹偏离的现象，建议适当提高螺旋匝道设计速度；部分螺旋匝道设计最小圆曲线半径可根据实际情况适当下调；对于设计速度较低的螺旋匝道，可通过提升超高值以保证实际运行速度的提升。

Driving Simulation and Key Design Index of Helical Ramp in Mountain City

The helical ramp is often taken as the scheme to connect the elevation difference between the two sides of the road because of restricts of road resource and other factors in the mountain city. Due to the lack of design criteria for helical ramps in existing studies, as a result, the design of helical ramp often follows the linear standard of circular ramp or even branch road. 7 helical ramps in the main urban areas of Chongqing are selected to carry out the natural driving experiments. The environmental model of road is established through Carsim simulation software to analyze and compare the key influencing factors to cause the trajectory offset of vehicles. The research result shows that when Carsim is used to establish the driver simulation model, the simulation result of closed-loop control mode is more reliable. The trajectory deviation occurs only when the simulation running speed exceeds the measured running speed by more than 62.5%. It is recommended to increase the design speed of helical ramp appropriately. The minimum circular curve radius in the design of some helical ramps can be properly reduced according to the practical situation. For the helical ramps with the lower design speed, the actual running speed can be increased by increasing the ultra-high value.