School of Highway, Chang'an University, Xi'an, China.
College of Transportation Engineering, Chang'an University, Xi'an, China.
PLoS One. 2021 Dec 30;16(12):e0261975. doi: 10.1371/journal.pone.0261975. eCollection 2021.
Under adverse weather conditions, visibility and the available pavement friction are reduced. The improper selection of speed on curved road sections leads to an unreasonable distribution of longitudinal and lateral friction, which is likely to cause rear-end collisions and lateral instability accidents. This study considers the combined braking and turning maneuvers to obtain the permitted vehicle speed under rainy conditions. First, a braking distance computation model was established by simplifying the relationship curve between brake pedal force, vehicle braking deceleration, and braking time. Different from the visibility commonly used in the meteorological field, this paper defines "driver's sight distance based on real road scenarios" as a threshold to measure the longitudinal safety of the vehicle. Furthermore, the lateral friction and rollover margin is defined to characterize the vehicle's lateral stability. The corresponding relationship between rainfall intensity-water film thickness-road friction is established to better predict the safe speed based on the information issued by the weather station. It should be noted that since the road friction factor of the wet pavement not only determined the safe vehicle speed but also be determined by the vehicle speed, so we adopt Ferrari's method to solve the quartic equation about permitted vehicle speed. Finally, the braking and turning maneuvers are considered comprehensively based on the principle of friction ellipse. The results of the TruckSim simulation show that for a single-unit truck, running at the computed permitted speed, both lateral and longitudinal stability meet the requirements. The proposed permitted vehicle speed model on horizontal curves can provide driving guidance for drivers on curves under rainy weather or as a decision-making basis for road managers.
在恶劣天气条件下，可见度和可用路面摩擦系数降低。在弯道上选择不当的速度会导致纵向和横向摩擦分布不合理，这可能导致追尾碰撞和横向不稳定事故。本研究考虑了联合制动和转向操纵，以获得雨天条件下允许的车辆速度。首先，通过简化制动踏板力、车辆制动减速度和制动时间之间的关系曲线，建立了制动距离计算模型。与气象领域常用的可见度不同，本文将“基于真实道路场景的驾驶员视线距离”定义为衡量车辆纵向安全性的阈值。此外，定义了横向摩擦和侧翻余量，以表征车辆的横向稳定性。建立了降雨强度-水膜厚度-路面摩擦系数的对应关系，以便更好地根据气象站发布的信息预测安全速度。需要注意的是，由于湿路面的摩擦系数不仅决定了安全车速，而且还由车速决定，因此我们采用法拉利的方法来求解关于允许车速的四次方程。最后，根据摩擦椭圆原理综合考虑了制动和转向操作。TruckSim 仿真结果表明，对于单辆卡车，以计算出的允许速度行驶时，横向和纵向稳定性均满足要求。该模型可为雨天弯道行驶的驾驶员提供驾驶指导，也可为道路管理者提供决策依据。
