| With the auto industry development and improvement of living standard, vichle is gradually entering the family, and the results is the non-professional drivers, traffic flow and vehicle density of high speed, traffic safety problem becomes increasingly prominent, so higher requirements are needed in the traffic management and vehicle safety.Speed is a core element of road safety issues, inextricably linked with the highway traffic efficiency, traffic efficiency and safety has been a contradiction. How to handle the relationship between safety and efficiency, doing the speed limit is a concern and a hot issue. The article analyze the safety speed affected by different road conditions, weather conditions under the free flow ,at the same time, research the the coordination relationship between capacity of highway and security ,and analysis the speed of different traffic flow condition impact, then computer the safe speed under the common influence of multi- factors by establishing model.the first is braking safety, establish the relationship model between speed and braking distance and analyze the speed of other factors effect of the model, given the safety speed on the driving brake; followed by the analysis of handling and stability, analyze the relationship between speed and the typical accidents (side touch, turn sideslip, roll) ,establish the appropriate speed - road dynamic model, given the safe driving speed based on manipulation of the stability of the highway; again the analysis of the car safety of turning braking condition , accroding to force analysis of automobile tires during cornering braking, establish the dynamic model of vertical and horizontal security, and get the safe speed; in this basis, consideration of relationship between the traffic flow capacity and the security on highway, to find out the safety speed when security and capacity are optimum under certain conditions. Finally, set the square speed of traffic flow as the evaluation criteria, use the fuzzy control method to evaluate the safety of traffic flow, and give the appropriate safe speed adjustment factor.based on the model ,the article design speed expressway traffic safety simulation model system. The simulation system has a window concise, and easy operation, can calculate the safe speed under different conditions. Calculate the safe speed under different parameters of cars and trucks. |
