Study on Braking Safety and Reliability of Highway Vehicles under a Heavy Rainfall Environment Based on Stopping Sight Distance

Based on the stopping sight distance and reliability theory, the braking safety reliability of road vehicles in heavy rainfall environment is studied. Starting from the principles of kinematics, the AASHTO model is improved, and the vehicle braking safety reliability model in heavy rainfall environment is established. Taking the vehicle speed, rainfall intensity and thinking time as random variables, the braking safety reliability and reliability sensitivity of road vehicles with different rainfall intensities and different vehicle speeds are researched by using Monte Carlo method. The result shows that (1) Compared with the original AASHTO model, the stopping sight distance calculation value obtained by the improved AASHTO model is larger and the difference value increases with the increase of vehicle speed. (2) the change of vehicle speed has great influence on the fluctuation degree of stopping sight distance, while the change of rainfall intensity has little influence on the fluctuation degree of stopping sight distance. (3) The safety speed limit in rainy days calculated by the deterministic method is dangerous, while more reasonable safety speed limit in rainy days can be obtained based on the reliability method. (4) There is a maximum value of the sensitivity of failure probability to the mean random variables. The maximum values of the sensitivity of failure probability to the mean vehicle speed and the sensitivity to the mean thinking time increase with the increase of rainfall intensity, while and the maximum value of the sensitivity to the mean rainfall intensity decreases with the increase of rainfall intensity. (5) There is a maximum value and a minimum of the sensitivity of failure probability to the standard deviation of random variable. The absolute values of the maximum and minimum of the sensitivity of the failure probability to the standard deviation of vehicle speed and the standard deviation of thinking time increase with the increase of rainfall intensity, while the absolute values of the maximum and minimum of the sensitivity to the standard deviation of rainfall intensity decrease with the increase of rainfall intensity.