山地城市长上坡路段小客车行驶速度的模式特征

与平原城市相比,山地城市道路具有弯道多、坡度陡、曲率变化大、交叉口间距长、路侧干扰少等特点,车辆的运行状态存在特殊性。关于小客车在上坡路段的速度变化特征此前一直存在不同推测。为明确山地城市长上坡路段小客车的行驶速度特性,在重庆市主城区内选择多条具有代表性的上坡路段为对象,采集多个测试断面的行驶速度,得到了小客车在夜间和日间的速度变化趋势和影响因素,以及大型车与小客车之间的速度差异、以及路段环境和昼夜因素对速度的影响。结果表明:1小客车在山地城市上坡路段的速度变化趋势呈典型的多样性特征,比如持续递减、维持不变、持续升高、以及不同类型的波动,共确定了6种变化模式;2面包车在上坡路段的速度均值最低、三厢/两厢轿车居中,SUV速度最高,SUV与面包车的平均速度相差约5 km/h;3在日间,道路坡度对小客车速度无明显影响,受路侧、交通量和信号灯影响更大;夜间小客车在上坡路段的行驶速度会出现衰减;4在直坡路段,小客车的夜间行驶速度高于日间,并且速度在各观测断面的分布比较离散;而对于弯坡组合路段,速度在各断面的分布比较集中,且速度幅值低于日间。

Pattern Character of Passenger Car Speed on Uphill Section of Mountainous City Streets

Compared with plain cities, mountain city streets have more corners, steep slope, frequently changed curvature, spacing long intersections, and less interference from roadside. Therefore, operation state of the vehicles has particularity. For passenger cars, it had been speculated there being different characteristics of speed change on uphill sections. To clarify the speed characteristic of passenger cars on mountain city street with a long uphill, this study chooses a number of representative uphill section in Chongqing main urban area, driving speed was collected on the pre-set cross-sections, trends and factors affecting speed of passenger car at night and day are obtained, as well as the speed difference between large vehicles and passengers cars, and the effect of road environment and circadian factors on speed. The results showed that: (1) The speed change of passenger cars on uphill section of mountain city was typical of the diversity of features, such as continuous decline, unchanged, continues to rise, and the volatility of different types; six modes for speed changes were identified. (2) On uphill, vans have the lowest average speed, then sedan/hatchback, SUVs have the highest speed; difference of average speed between SUV and minivan is about 5km/h. (3) The slope had no significant effect on passenger cars speed in the day, but the roadside, traffic volume and traffic lights have a greater impact on passenger car speed; however, at night small passenger car speed attenuates on uphill. (4) On slope of straight sections, passenger car driving at night faster than during the day and speed distribution is more discrete on each observation point; but for curved slopes, speed distribution is more concentrated on each observation point, and the velocity amplitude is lower than during the day.