螺旋匝道（桥）小客车横向行驶特性实测研究

螺旋匝道和螺旋桥的数量近年来与日俱增，但其驾驶行为模式和汽车运行特征一直未得到明确，为此，在涪陵长江一桥、乌江二桥、重庆融侨大道和涪陵金凯装饰城环形高架4处地点开展了螺旋匝道实车驾驶实验，采集了自然驾驶状态下的汽车连续行驶轨迹、横向加速度以及周围行驶环境等信息. 基于自然驾驶数据，得到了螺旋匝道范围内汽车横向加速度的变化模式、幅值特性、影响因素，以及驾驶人的车道使用特性. 研究结果表明:汽车横向加速度幅值在螺旋匝道范围内的变化趋势有多种模式，包括保持恒定、单调上升、单调下降、鼓型等；内圈匝道的横向加速度高于外圈；在单向行驶匝道上，横向加速度实测值远高于规范中的推荐值甚至超出可忍受范围，导致一部分被试行驶时横向舒适性较差；匝道半径和行驶空间对横向加速度幅值有显著影响，行驶空间保持一定时，横向加速度与匝道半径成负相关关系；单幅混合双向行驶的螺旋匝道，横向加速度幅值最低；对于单向双车道螺旋匝道，不管是上行方向还是下行方向，使用内侧车道是占主要比例的驾驶行为. 

Field Tests on Lateral Operational Characteristics of Passenger Cars on Helical Ramps (Bridges)

Helical ramps and helical bridges are widely used in recent years, however the driving patterns and dynamic characteristics of vehicles running on them are still unclear. Therefore, to obtain the driving pattern of passenger cars on helical ramps (bridge), driving tests using real cars were carried out on Fuling Yangtze River Bridge, Second Fuling Wujiang River Bridge, Rongqiao Helical Bridge and Jinkai Helical Bridge in Chongqing. Trajectory and lateral acceleration speed of cars under drivers’ naturalistic driving were continuously collected, as well as environment information. Based on naturalistic driving data, the variation, amplitude and influencing factors of speed and lateral acceleration were obtained, together with lane usage pattern. It was found that diversified lateral acceleration patterns on helical ramps were observed, such as stabilized, increasing, deceasing, and drum-typed. Larger lateral acceleration were recorded on ramps along the inner ring than on ramps along the outer ring. Lateral acceleration measured on some one-way ramps are significantly higher than the recommended valve in highway design guidelines and even exceeding the unbearable threshold, which cause passengers discomfort in side direction. Ramp radius and driving space greatly affect lateral acceleration, lateral acceleration drops as ramp radius increases if driving space holds constant, and the smallest lateral acceleration was measured on mixed two-way helical ramp. For one-way helical ramps with two lanes, regardless of on upward ramp or downward ramp, driving on inside lane accounted for a major proportion of driving patterns.