| As China’s urbanization process accelerates,the city continues to expand.The highways in the city’s surrounding areas are more prone to streetization and urbanization,and gradually become urbanization regional highway.As an important corridor for the city’s external passenger and freight transportation,these urbanization regional highways face more prominent traffic congestion problems in the actual operation process.These problems have a significant bad effect on the safety and smoothness of the city’s external traffic and hindered the city’s social and economic development.Based on the research results of our team,the road traffic congestion in Wuhan’s urbanized areas mainly occurs in the upgrade sections with large slopes and joint sections where the number of lanes is changed.And the traffic bottleneck as a result of the low speed of large trucks and the traffic disturbance due to the vehicle lane change are the main causes of the traffic congestion in these two sections respectively.Therefore,the paper will research the key indicators of road profile and the transition section of road lane change in China.Firstly,in order to study the climbing ability of six articulated trains,which is the mainstream of freight cars in China,Dongfeng Tianlong tractor(DFH4251AX4AV)is selected as the target vehicle in the current research.It’s found that the climbing ability of the target model does not meet the requirements of the current design specification of the road longitudinal slope in China.Hence,a new design criteria for the longitudinal slope and slope length of the urban area is proposed.Then,the paper compared the difference design index of vertical curve limit minimum radius between the urban road and highway,find that the main reason of the difference between the two specifications is that the calculation methods and parameters of the stopping sight distance is different.Thus,based on the unification of two road line-of-sight indicator,the paper proposes a new vertical curve design indicator for urbanized areas.Finally,according to the fifth-order polynomial trajectory model,the paper studies the calculation methods of lane change trajectory equation under different design speeds and lane change widths,and calculated the value of the design indicators of the transition section with different speeds and lane change widths between highway and urban road. |
