Research on the Ultimate Velocity and the Ultimate Height of Gravity Center of Vehicles Going through Roadway Curve to Avert Rollover

The results of a study on the ultimate velocity and the ultimate height of gravity center of vehicle to avert rollover while the vehicle going through roadway curve are reported in this paper. An improved mathematical model is developed. The relationship between the ultimate velocity to avert rollover and the relative parameters, and the variations of the ultimate height of gravity center of the vehicle to avert rollover with the relative parameters while the vehicle going through roadway curve are obtained. The results show that in order to avert rollover, the ultimate velocity for the bus involved in Karuizawa Bus Accident should be limited to 77.2 km/h while going through Karuizawa roadway curve. However, the bus velocity recorded was 96 km/h, which exceeded the ultimate velocity and can be considered as one of the important causes that lead to the bus rollover accident. The ultimate vehicle velocity decreases with wind speed increasing for the studied four types of vehicles. The larger the lateral projection area of vehicle, the smaller the ultimate vehicle velocity to avert rollover. The ratio of H/W (the ratio of the ultimate height of gravity center to distance between the right and left wheels) of vehicle will influence the ultimate vehicle velocity and the ultimate height of gravity center to avert rollover markedly. The longitudinal gradients ? of roadway surface plays a role in increasing the risk of vehicle rollover.