基于高空视频图像的山地城市信号交叉口到达车辆运行特征分析

An Analysis of Operating Characteristic of Vehicles at Signalized Road Intersections in Mountainous Cities Based on Aerial Video Data

为明确山地城市信号交叉口到达车辆的运行特征及其影响因素,通过无人机采集4个位于山地城市的道路信号交叉口的高空视频图像数据,利用基于DataFromSky云平台的AI视频分析技术,获得车辆运行参数。基于车辆运行时空图,得到了交叉口直行道停止线前车辆停滞延误特征、停止线位置车头时距和车头间距统计特征,分析车头间距、停止线截面处速度及道路平均坡度之间的相关性。结果表明:不同路段同一排队位次和同一路段不同排队位次的车辆运行特征均有所不同,排队位次越靠前的车辆,停车点分布区间越集中,下坡路段整体停车位置分布范围比上坡路段大;无论是上坡、下坡,还是缓坡,排队位次越靠前的车辆停滞延误分布范围越大,而靠后的车辆停滞延误分布范围小,最大值出现在下坡路段;不同路段类型车头时距分布均集中于1.5 s,上坡路段的车头时距离散程度最大,但峰值比下坡路段和缓坡路段小;不同路段类型的车头间距分布均集中于10 m,上坡路段和下坡路段车头间距分布出现左偏现象,而缓坡路段车头间距分布更为集中;车头间距在上坡、下坡和缓坡路段均和车辆经过停止线位置处时的速度存在较强的正相关性;道路平均坡度与相邻2车车头间距存在正相关性。

In order to identify operating characteristics of vehicles approaching signalized intersections in mountainous cities and their influencing factors, aerial video data of the traffic are captured at four signalized intersections in a mountainous city by drones. The operating characteristics of vehicles are extracted by AI video analysis from DataFromSky cloud platform. Based on a time-space diagram and the obtained data, the statistics of delay value,time headway and space headway before stop lines of straight lanes at intersections are calculated. Moreover, the correlations between the space headway, speed of a vehicle passing through the stop line, and average gradient of road are analyzed. The results show that the operating characteristics of a vehicle vary with its position in a queue.Furthermore, even with the same position in a queue, the operating characteristics of a vehicle still vary with different road sections. When waiting behind a stop line, the distribution of stop positions of vehicles closer to the stop line is more concentrated than that farther from it. The overall distribution of stop positions of vehicles is more dispersed in downhill sections than that in uphill sections. No matter it is an uphill section, a downhill section, or a gentle slope, the distribution of delay at a location closer to the stop line is larger than that at a location farther from it,and the maximum value of delay appears in the downhill sections. The distribution of time headways is concentrated at 1.5 s for all types of road sections, and it is more dispersed in uphill sections than that in downhill sections or gentle slopes, but the maximum value of time headways in uphill sections is smaller than that in downhill sections or gentle slopes. The distribution of space headways is concentrated at 10 m for all types of road sections, and it is skewed to the left in uphill and downhill sections, while that is more symmetric and concentrated to the mean value in gentle slopes. For all types of road sections, there is a strong positive correlation between space headway and the speed of a vehicle passing through the stop line. Besides, there is a positive correlation between average gradient of road and space headway of adjacent vehicles.