Analysis Of Driving Stability And Speed Management Strategies Of Curved Road Sections Of Mountain Expressways

With the continuous improvement of social and economic levels,the development of expressways in China is changing rapidly,especially in the mountainous areas of western China,which has been vigorously developed and improved.What follows is the speed limit between expressways and people ’s increasing vision of “speed-up Contradictions have become more intense.However,speed limit improvement is a very complicated and sophisticated project that cannot be achieved overnight.Most current speed management is mainly tunnels and long downhill sections.However,for the curved road sections with lower design indicators in mountain highways,Very few,so this paper studies on the background of the speed increase demand of highways and the driving safety of curved road sections.First of all,this paper takes the curved road section of mountain highway as the research object,analyzes its basic linear combination and traffic operation characteristics,and finds that the accident loss and severity of the curved road section are relatively large through accident statistics.Rollover is the main factor.Therefore,it is an important part to improve driving safety to ensure the driving stability of vehicles on curved road sections.The main influencing factors of safe driving are analyzed from the running speed,road conditions and weather conditions.Secondly,taking the driving stability as the starting point,taking the occurrence of side slip and rollover accidents as the safety critical state,and using multi-degree of freedom vehicle dynamics,the vehicle-coupling safety speed model of the curve section is established.Using this model to calibrate the design parameters of highways and the parameters of large and small vehicle models,the influence of the radius of the circular curve,the adhesion coefficient of the road surface,the super high cross slope and the longitudinal slope on the driving stability was analyzed.When the road design index is low and the pavement conditions are poor,the safe speed may be less than the design speed.And using Carsim/Trucksim vehicle dynamics simulation found that the calculated value of the model is slightly smaller than the simulated value,thus verifying the correctness of the model in this paper.Finally,the problems in the existing speed limit are analyzed.Based on the vehicleroad coupling safe speed model and the running speed model,the safe speed coefficient is introduced to divide the speed management strategy of the curved road segment into the speed limit zone and the recommended speed limit.From the perspective of driving safety,running speed coordination and running efficiency,the methods of determining and setting the speed limit value for different speed management strategies are discussed.Considering the partial speeding behavior,the compensation deceleration distance is proposed,and the leading distance of the curve under different strategies is optimized.Taking the typical mountain expressway Chengyu Expressway as an example,the speed management method is divided by using the safe speed factor,and the curving or curvilinear combination road section and the layout method of the speed limit zone management and the recommended speed limit management are determined.