Based on the mechanical calculation, this paper comprehensively considers the safety, passenger comfort, environmental factors, construction and maintenance, traffic composition and other factors of the small bus, and proposes that the maximum ultra-high value of the special ramp for small bus on the expressway should be 10% under the condition of non-snow and ice.The maximum ultra-high value in snow and ice covered environment should be the recommended value of 8%. On this basis, the article compares the advantages and disadvantages of point mass-rigid body calculation model (PMR) and point mass-suspension calculation model (PMS), and proposes an ultra-high calculation model suitable for passenger cars. Finally, a new distribution model of ultra-high and transverse force coefficient based on dangerous speed is proposed.This model takes into account the general overspeed situation of small buses, which can guarantee the lateral stability of small buses running at low speed or normal speed, and can also improve the lateral stability and comfort of small buses running at high speed. According to the new distribution model, it is possible to calculate the recommended values for the super-high setting of different design speeds and radius intervals for the special ramps of the passenger cars.

CICTP