Study Of Safety Drive On Expressway Under Partly Hydroplaning

If water between tires and the ground cannot be completely excluded and tires float upward even out of the ground completely when tires are rolling on a wet way, then a phenomenon called partly hydroplaning occurred. Once the partly hydroplaning happens, the friction coefficient between tire and road surface decreases significantly, less experienced drivers are more vulnerable to making misjudgments toward speed and distance during driving and braking, which lead to traffic accidents. Therefore, in order to determine the safe driving speed and distance and guarantee the safe traffic environment on highway in the rain, it is vital to study water film's influence mechanism and rules between the tire tread and road surface.The paper relies on the western technology project of Ministry of Communications—Research on Expressway Safety Operation Strategies Under Atrocious Weather Conditions, and studies key issues of hydroplaning for sedan cars on rainy days.First, tire's compressive deformation capability and market share are considered to select the appropriate representative tires. Three-dimensional finite element model of tire possessing vertical and horizontal grooves is established based on correlation parameter. Tire deformation of representative vertical loading is simulated by software; then after adjusting the water film thickness, FLUENT is used to study hydrodynamic pressure suffered by the tire model under different driving conditions to got the critical hydroplaning speed.On the basis of analyzing the influence factors about of tires and wet road's adhesion coefficient, the road adhesion coefficients under different driving conditions, such as speed, water film thickness, is researched. And according to hydrodynamic pressure when partly hydroplaning happens, representative models'stopping sight distance is calculated. Meanwhile, by analyzing the relationship between rainfall intensity and visibility, drivers'reaction distance rule in the rain, and by combining road longitudinal slope, radius of circular curve environment and other factors, longitudinal stopping sight distance and the amendment safe speed of expressway on the rainy day are proposed.Finally, according to the research results of stopping sight distance and safe speed under partly hydroplaning, velocity (distance) feedback instrument workflow and layout methods are designed. To reduce the accident of partly hydroplaning by misjudgment, highway management departments'setting the velocity (distance) feedback instrument in the steep and dangerous sections of sharp bends combined with Chevron confirmed signs are recommended.