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.

The effect of rainfall on high-speed train includes aerodynamic force and impact force of raindrop. Previous studies focused on the effect of rainfall on aerodynamic characteristics of high-speed train. In this paper, based on Marshall-Palmer raindrop size distribution, Euler-Lagrange method is used to establish the aerodynamic model of high-speed train under rainfall environment, and the influence of rainfall on flow field characteristics and aerodynamic characteristics of high-speed train is studied. Based on the energy conservation method, the formula for calculating the impact force of raindrops on the train is derived, and the characteristics of rain load on the train are analyzed. The results show that when the vehicle speed is the same, the longitudinal rain load coefficient, vertical rain load coefficient, aerodynamic drag coefficient and aerodynamic lift coefficient of the head car increase with the increase of rainfall intensity; When the rainfall intensity is the same, the longitudinal rain load coefficient, vertical rain load coefficient, aerodynamic drag coefficient and aerodynamic lift coefficient of the head car decrease with the increase of vehicle speed.