山区双车道公路运行速度预测模型的加速度标定

Calibrating of acceleration and deceleration rate for the operating speed prediction models of two-lane roads in a mountainous area

摘要:

为标定运行速度模型中的汽车加速度值，在山区双车道公路上开展小客车连续行驶实验，采集轴向加速度的连续数据，并通过断面观测得到大客车和大货车的加速度值，获得峰值加速度的累积频率曲线以及统计分布特性，并建立加速度-道路几何参数关系模型.结果表明：小客车的入弯减速度幅值要比出弯加速度高一倍左右，不宜将加、减速度简化成同一个值，应该分别进行标定；加速度和减速度累积频率曲线的斜率突变点都不是发生在85^th百分位，而是临近95^th，应重新考虑85^th百分位的使用价值；大客车的加、减速度幅值非常接近，而重载货车的减速度要明显大于加速度，同时，重载货车的加速度和减速度值要双双低于大型客车；小客车的加速度与弯道半径负相关，而与弯道转角正相关.

Abstract:

To determine the acceleration and deceleration rate for the operating speed prediction model, the continuously driving tests of passenger car, bus, and heavy trucks were carried out on two-lane roads in a mountainous area. Longitudinal acceleration of vehicles was collected, and the cumulative frequency curves of peak acceleration and deceleration rate were analyzed. The statistical distribution and the eigenvalues of acceleration (a_x) and deceleration (a_b) were obtained, and the models of a_x and a_b with road geometry parameters as independent variables were established. The results show that: due to that the magnitude of a_b of passenger cars is about twice higher than a_x, the a_x and a_b could not be simplified to a same fixed value. Slope breakpoint of cumulative frequency curve of a_x and a_b does not appears on the 85^th percentile but near the 95^th percentile. The a_x and a_b of large buses display very close amplitude, and a_b of heavy-duty trucks is significantly greater than a_x. a_x and a_b of heavy-duty trucks are lower than large buses'. There is a negative correlation between longitudinal acceleration of passenger car and curve radius, and a positive correlation with curve deflection angle.