基于车速平稳过渡的高速公路出口限速方案

研究能够满足出口车速平稳过渡的逐级限速方案，对提高出口区域车辆平稳运行及安全提升有重要意义。利用无人机采集高速公路出口车辆运行参数，分析出口车辆运行特征，考虑驾驶员对相邻限速标志的认知反应，构建了连续限速标志设置间距计算模型，建立了高速公路出口不同级别的限速方案，利用驾驶模拟试验对设计的不同限速方案进行分析及评价。模型的计算结果显示，二级限速方案中，限速值为60-40km/h的限速标志间距为160m；三级限速方案中，限速值为80-60-40km/h的限速标志间距分别为：300，80m，限速值为90-60-40km/h的限速标志间距分别为300，85m；四级限速方案中，限速值为100-80-60-40km/h的限速标志间距分别为295，160，80m。利用驾驶模拟器对模型结果进行验证，试验结果表明：逐级限速方案的平均减速度指标小于1.3 m/s2，均在驾驶舒适性阈值内；随着限速级数增加，车辆离散幅度显著降低，表明逐级限速方案对出口车辆运行速度有明显管控效果；四级限速方案可使在分流鼻端车速标准差、平均减速度、V85分别控制在5.23km/h、0.52m/s2、54km/h左右，极大了满足车速平稳过渡要求。可见，借助模型定量优化的逐级限速方案可以显著提高出口车速过渡的平稳性和安全性。

Research on expressway exit speed limit scheme based on smooth speed transition

It is of great significance to study the step-by-step speed limit scheme that can meet the smooth transition of export speed to improve the smooth operation and safety of vehicles in the export area. Using the UAV to collect the operating parameters of the vehicle at the exit of the expressway, the operating characteristics of the vehicle at the exit are analyzed. Considering the driver ''s cognitive response to the adjacent speed limit signs, the calculation model of the setting spacing of the continuous speed limit signs is constructed, and the speed limit schemes of different levels at the exit of the expressway are established. The driving simulation test is used to analyze and evaluate the different speed limit schemes designed. The calculation results of the model show that in the two-stage speed limit scheme, the speed limit sign spacing with a speed limit value of 60-40km/h is 160m ; in the three-level speed limit scheme, the speed limit sign spacing with a speed limit value of 80-60-40km/h is 300,80m, and the speed limit sign spacing with a speed limit value of 90-60-40km/h is 300,85m ; in the four-level speed limit scheme, the spacing of speed limit signs with a speed limit value of 100-80-60-40 km/h is 295, 160 and 80 m respectively. The model results are verified by driving simulator. The test results show that the average deceleration index of the step-by-step speed limit scheme is less than 1.3 m/s2, which is within the driving comfort threshold. With the increase of the speed limit series, the vehicle dispersion amplitude is significantly reduced, indicating that the step-by-step speed limit scheme has obvious control effect on the running speed of export vehicles ; the four-stage speed limit scheme can control the standard deviation, average deceleration and V85 of the speed at the diversion nose at 5.23km/h, 0.52m/s2 and 54km/h respectively, which greatly meets the requirements of smooth transition of the speed. It can be seen that the step-by-step speed limit scheme optimized by the model can significantly improve the stability and safety of the exit speed transition.