Study On The Traveling Velocity Character And Trajectory Character Of Vehicle In Mountainous Two-Lane Highway

More than two thirds territory of China are mountainous areas,and fatal traffic accidents happening in mountainous areas have caused great thread to people's lives in recent years,hence,the traffic safety of mountainous complex roads should not be ignored.In fact,the abnormity of travelling speed and travelling trajectory of the vehicle are always the direct cause to traffic accident in mountainous highway.While In existing researches,relatively less studies on characters of travelling speed and trajectory of vehicles can be found.As a result,the studies about characters of travelling speed and trajectory of vehicles have very important practical significance about improving the traffic safety in mountainous highway.In this thesis,six two-lane mountainous roads in Chongqing together with the vehicle and many drivers are selected to make vehicle-road tests.Based on the test results,analysis software,such as VBOX,EXCEL,MATLAB,SPSS,and theories,like correlation analysis and other mathematical method are used to analyze the travelling speed and trajectory regularity of vehicles on several types of roads;comparative analysis are made on the travelling speed and trajectory characters of vehicles driven by different drivers on single curve and continuous curves sections;An index named MSRC is proposed to evaluate the safety of a curve,analysis are made on the relationship model of MSRC and accident rate.Also,the distribution characteristics of the minimum radium of vehicle trajectory are discussed.The research results show us: the change of road height in curve sections has strong influence on travelling speed;the driving direction on flat road sections has little influence on continuous travelling speed;the vibration frequency of continuous travelling speed on linear complex uphill road sections increases obviously by comparison to which on the linear flat sections,however,the vibration amplitude has the tendency to decrease;the curve of vehicles speed are similar to parabola curve when the vehicle travels through a single curve bend;to the same curve section,dispersion degree of running speeds in driving out of the curve are higher than that into the curve;fluctuation range of trajectory curvature in driving downhill are higher than that in uphill,and fluctuation range increases in curved slope combination sections;fluctuation range of trajectory curvature is high in long downhill and multi bend roadsections,but in long uphill and multi bend road sections,the trajectory curvature is 1.5bigger than it in flat road sections;in curved road sections,the ratio between average travelling speed out the curve and average travelling speed in entering the curve gradually increases and approaches to 1 means the driving safety is declining;in curved road sections,the difference between the road radius and the minimum radium of vehicle trajectory is common and the dispersion of the difference becomes lower when the road radium gets bigger.The research result in this thesis may be a suggestion to the study on travelling regularity of vehicles running in mountainous areas,meanwhile,the research result in this thesis may be applied to evaluate the geometric linear safety of mountainous roads,at the same time,the research result in this thesis may provide new thought for road safety study based on travelling trajectory of vehicles.