The Setup Of Climbing Lanes In The Reconstruction And Extension Project Of The Arterial Highway In Guizhou Province

With the continuous improvement of the reconstruction and extension project of the national and provincial arterial highways in Guizhou Province,the demand for highway traffic capacity and transport efficiency has been further improved.In view of the unfavorable conditions in Guizhou,climbing lane can be set up with the consideration of traffic capacity,traffic safety and project cost.The unfavorable conditions include the complicated terrain and geological conditions,the difficulty of environmental protection work,the low alignment technical index,the adoption of large and long longitudinal slope or combined slope sections,the serious conditions for passenger and freight vehicles mixed in lanes and frequent traffic accidents.The construction of climbing lane is an important measure to divide the fast vehicle and slow vehicle,increase the degree of driving freedom for vehicles,make full use of traffic capacity and transport efficiency and improve the driving safety.The paper,based a large amount of measured data collected from S106 Liuzhi Laojie to Shibangou Grade-II Highway in Guizhou Province(the new poverty alleviation and reconstruction project of national highway),analyses the running characteristics of vehicles when driving on the upgrade sections with longitudinal slope less than 3% and more than 3%.Besides,the speed change law of trucks on the upgrade sections is obtained.The change of longitudinal grade and slope length has little effect on the driving performance of the passenger car.However,it has a significant impact on the trucks uphill running characteristics,especially the long steep sections.After entering the uphill section,the running speed of truck reduce obviously,especially at a distance just entering the uphill,and then the rate of speed reduction slows down until it reached a steady driving state.According to the traffic volume survey of some Grade-II Highway in Guizhou Province,the tonnage cumulative curve of truck is drawn and 85% tonnage is determined as a fixed proportion.17 t is selected as the tonnage of the representative models which can meet the design requirements today,and the EQ1228v19D2 truck with 8.05kw/t power-to-weight ratio is further confirmed to be the leading model of the trucks.Based on the vehicle driving theory,the running on the uphill sections of truck is studied and analyzed.With the technical parameters of the leading vehicle model,the equilibrium slope length and the equilibrium slope are calculated theoretically and the climbing performance curves under different slope are plotted.Then,the relationships between the longitudinal slope,slope length and running speed are analyzed including the influencing factors of the slope length limitation.In view of the characteristics of reconstruction and expansion project,the paper analyzes the setting principles of climbing lane from aspects of traffic capacity,traffic volume and composition,and studies the specific construction conditions and requirements of climbing lanes from the plane,cross-section and traffic engineering facilities.At the same time,the setting details of climbing lanes in each example are analyzed with the example of the specific reconstruction and expansion project of highways in Guizhou Province.