Analysis Of The Setting Conditions Of The Climbing Lane Of The Secondary Road In Mountain

Because of restriction of the terrain,topography and engineering construction and other factors,the secondary road with double lane in mountain area often adopts large and long longitudinal slope,which forms the climbing section.In which the running state of heavy-duty lorry is affected heavily by road longitudinal slope due to its lower power to weight,its speed slowed.Furthermore,with the restriction of the number of lanes,trucks,lower speed,could cause serious influence on upslope direction traffic capacity of cars which have higher speed.The setting of the climbing lane could reduce the influence of slope of climbing section of the secondary road,but the unreasonable setting not only has little influence on the improvement of the car traffic capacity,but also wastes resources.This article,originated from research project of Shaanxi Provincial Transport Department,15-27K: ‘Research on decision making techniques for climbing lane of two lane highway in mountain area’,systematically analyzed the effect of the climbing lane through demonstration on increase of the absolute and relative quantity of the upgrade direction car traffic capacity caused by the setting of the climbing lane.This could provide reference and guidance for the setting of the climbing lane and ensure the setting scientific,reasonable.This article analyzed the characteristics of overtaking,following and vehicle confluence to determine the models and the mandatory lane changing probability.On the basis of the investigation of a section of the highway of Jiangmei(Meitai line)with an average slope of 4.3% and slope length of 2.89 km,this article determined the speed change conditions of truck and car and the dominant truck model.By theoretical analysis and computer simulation,the equilibrium speed and equilibrium slope length of 3%,4% and 5% longitudinal slope sections are determined.On the basis of introducing the principle of cellular automata,the influence of the slope gradient on the speed of the truck is introduced in the cellular automata model.Moreover,the speed optimization model,the model of the constant speed and acceleration overtaking of car utilizing the reverse lane and mandatory lane changing probability were introduced into cellular automaton.The road model was established in accordance with the speed of the load truck influenced by the slope of the secondary highway in the mountainous area.The simulation scheme was determined through the analysis of the influence of the road and traffic conditions of the secondary road.On the basis of the elimination of impact of traffic volume on the simulation data,this article analyzed the impact of traffic composition,traffic volume,climbing lane ratio and longitudinal slope on the uphill direction car traffic capacity.Furthermore,this article also analyzed the impact of the setting of climbing lane on the double direction truck and downhill direction car traffic capacity.Principal component analysis was used to determine the setting order of the influence of the climbing lane,multiple regression was made for the amount of the car added by the climbing lane.Then the conditions of setting up the secondary road in mountain area were put forward.