高密度立交出入口车辆纵向运行特性

为明确车辆在高密度互通立交主线入口、出口以及连接段的纵向运行速度特征，在重庆市选取了5座立交为研究对象，开展了47名驾驶员的小客车实车驾驶试验。通过speedbox和mobileye等实验仪器采集的数据，包括车辆运行速度、纵向加速度等，对数据进行处理并按入口、出口及连接段分类提取数据，绘制出对应的速度曲线图，以明确车辆在高密度互通立交出入口以及连接段的纵向运行特性。分析结果表明：入口处速度趋势有两类，平行式入口是上升—平稳，直接式入口是持续上升，平行式入口速度均值高于直接式，平行式入口速度标准差小于直接式；不同类型入口对驾驶人的加速操作选择具有一定影响；平行式入口在纵向加速度均值上较直接式入口低；出口处速度分布整体呈平稳下降趋势，平行式的运行速度均值低于直接式，但速度标准差却更高；出口速度变化特征点受驾驶人在主线出口减速偏好性影响；平行式出口减速度最大值与均值均大于直接式；相邻立交净距较短时，连接段的速度变化较为平缓，并且不同驾驶人的速度幅值比较接近；而常规净距的相邻立交，连接段的速度波动性大且离散。研究成果为高密度互通立交出入口及连接段的安全性评价以及安全改善提供了理论支撑以及基础数据支撑。

Vehicle Longitudinal Operating Characteristics at the Entrance and Exit of High-density Interchange Based on Field Driving Test

In order to clarify the longitudinal running speed characteristics of vehicles at the entrance, exit and connection sections of high-density interchanges, five interchanges in Chongqing were selected for the study, and a minibus driving test with 47 drivers was conducted. The data collected by speedbox and mobileye, including vehicle speed and longitudinal acceleration, were processed and extracted by entrance, exit and connection sections, and the corresponding speed profiles were plotted to clarify the longitudinal operating characteristics of vehicles at entrances and exits of high-density interchanges and connection sections. The analysis results show that there are two types of speed trends at the entrance, parallel entrance is rising-steady and direct entrance is continuously rising, the mean value of parallel entrance speed is higher than that of direct entrance, and the standard deviation of parallel entrance speed is smaller than that of direct entrance; different types of entrances have certain influence on the driver''s choice of acceleration operation; parallel entrance has lower mean value of longitudinal acceleration than that of direct entrance. The overall speed distribution at the exit shows a smooth downward trend; the mean value of running speed of parallel type is lower than that of direct type, but the standard deviation of speed is higher; the characteristic point of exit speed change is influenced by drivers'' preference of deceleration at the exit of main line; the maximum value and mean value of exit deceleration of parallel type are larger than that of direct type; when the net distance between adjacent interchanges is shorter, the speed change of connecting section is flatter and the speed amplitude of different drivers is closer. In contrast, the velocity volatility of the connecting section is large and discrete for adjacent interchanges with regular clearances. The research results provide theoretical support and basic data for the safety evaluation and improvement of the entrances and exits of high-density interchanges and their connecting sections.