高速公路出入口与主线纵坡间净距对行车速度影响仿真分析

高速公路出入口与主线纵坡净距较小时,车辆上下坡时易受分合流影响,速度变化差异性较大,不利于行车安全。为研究纵坡车辆速度实时变化规律,基于出入口与主线纵坡间最小净距,利用三维虚拟现实仿真软件UC-win/Road建立入口-上坡与下坡-出口路段仿真模型,通过Forum8驾驶模拟仪进行实验并采集数据。通过控制变量法调整大型车混入率、分合流比例等特征指标；构建速度度量模型,量化特征指标与速度之间的关系,针对特征指标进行单因素敏感性分析。结果表明：分合流比例及大型车混入率对速度变化影响显著；不同类型车辆的速度大小和变化趋势差异性较大。其中,大型车混入率对上坡段车辆运行状态影响较大,而分流比例对下坡段车辆运行状态影响较大；大型车混入率和分合流比例分别为30%~40%、10%~15%时,速度波动最大,敏感性较强。研究结果可用于为出入口与主线纵坡净距较小时的车辆运行管理及安全措施改进提供理论依据。

Simulation Analysis of Influence of Clear Distance between Ramp and Longitudinal Slope of Main Road on Driving Speed

When the clear distance between the ramp and the longitudinal slope of the expressway is small, vehicles are easy to be affected by the diverging and merging when going up and down the slope, and the variation of speed is large, which is not conducive to driving safety. Based on the minimum clear distance between the ramp and the longitudinal slope, UC-Win /Road was used to establish the Inlet-uphill and downhill-exit section simulation model, and the experiment was carried out with Forum8 driving simulator and data were collected. The control variable method was used to adjust the characteristic indicators such as the mixing rate of large vehicles and the proportion of diverging and merging to study the real-time variation law of vehicle speed in longitudinal section. A velocity measurement model was built to quantify the relationship between the characteristic indicators and the velocity, and a single factor sensitivity analysis was conducted for the characteristic indicators. The results show that the change of ratio of diverging and merging and the mixing ratio of large vehicles have significant influence on the speed change, and the velocity magnitude and change trend of different vehicle types are quite different. The change of mixing ratio of large vehicles has a great influence on the running state of vehicles in the uphill section, while the change of diverging ratio has a great influence on the running state of vehicles in the downhill section. When the mixing ratio of large vehicles and the ratio of diverging and merging is 30%~40% and 10%~15% respectively, the velocity fluctuation is the largest and the sensitivity is strong. The research results can be used to provide a theoretical basis for vehicle operation management and improvement of safety measures when the clear distance between ramp and the longitudinal slope is small.