The Research Of Mountain Area Road Bend Design Theory Based On Vehicle-road Coupling Safety Evaluation Model

Due to the special geographical conditions as well as the dual economic constraints of the budget, the western mountain road is resulted in some sections which can only be close to or lower than the actual design specifications at the early time. A mountain road can simultaneously exist grown downhill, curve and a combination of curved and dangerous road, and this giving the risk when vehicle is running. With the rising rates of vehicle ownership, the accidents of west region have become increasingly prominent. Taking Chongqing as an example, the rate of Chongqing mountain highway accident increased year by year, and this resulting in serious economic losses. If we can give a scientific and rational design theory before the highway alignment designed, the accident rate can be able to reduce effectively. With the "along the way" policy guidelines published this year, it will set off a new round of road construction in western China. Identify the cause of frequent accidents, improving the design specifications is the purpose of this article.Curve sections of mountain road have a higher traffic accident rate per mile than straight sections, and the curve accidents mainly include rollover and sideslip. This paper presents an effective method for evaluating the design specifications of the curve sections of mountain road. Usually the safety evaluation of road alignment is based on the test trial, but due to the road test experiments of curve sections are too dangerous, we use a computer simulation. First, by analyzing the mechanical characteristics of the vehicle when driving in the curves, study from the whole vehicle and from the front and rear axle, the state of the vehicle rollover and sliding, the establishment of the force model consists of horizontal curve radius parameters. Using formula to calculate the minimum radius values and comparing with norms minimum radius value. The results of the radius is close to the limit the minimum radius, and the rear axle of the previous analysis of the calculated values are generally close to the minimum radius, proving the rationality of the formula. Compare the pros and cons of different vehicle simulation software and determine the use the simulation software Carsim. First establishing the vehicle- road model, making model about the state of sliding and rollover, and this can establish a road when the car skidding parameters studied. Comparing different radius, different ultrahigh, different simulation models, the simulation result data linear fitting curve design to determine the threshold level, the threshold is much less than the specified value. Re-definition of the vehicle skidding, taken vehicle lateral yaw angle factors as a research, determining the critical value. Through simulating, it provides vehicle steering angle, the front and rear side of the angle. Takes the data into the formula to calculate the critical value of radius and makes linear fit to the data. Ultimately determining the level curve design reasonable threshold, and also proved the accuracy of Carsim software.This research provides a theoretical reference about safe driving of vehicle in the curve sections, put forward a reasonable proposal on the existing specification values, the research has a certain practical significance.