Mountain Road Steep Sections Of Additional Climbing Lane

At present, with the implementation of the national road network of Shandong, the road construction has turned to the mountainous areas, which requires that the roadway capacity chould be increased and traffic safety be improved. Larger and longer longitudinal gradient or composite gradient has to be employed, because of the limitation of the terrain, geological conditions, the difficulties in the work of environment protection and so on. It also has much influence on the road traffic. The climbing lane is an effective means by which to increase roadway capacity and improve safety, on mountainous and rolling terrains where significant trucking prevails.Based on great amount of field data and aimed at the present traffic circulation situation of the specific upgrades, the paper studied the regularity of free flow speed along grade and grade length in different gradient, namely for upgrade vehicles, the steeper in grade, the greater in vehicle speed reduction under the same grade length; the longer of grade length, the greater in vehicle speed reduction under the same gradient. Operating speed of passenger car did not fall much on 4%-5% upgrades, but the influence on truck is big, especially the section of upgrades which entered the upgrades at first. Afterwards the truck speed dropped slow, reduced to an end it can achieve a kind of stable, constant travel condition.Based on the truck climbing travel characteristics, the truck power-to-weight ratio computation model was put forward, the performance of 15% truck power-to-weight ratio used in the longitudinal gradient design typical truck was adopted, and a set of definite power-to-weight ratio experimental plan was proposed. Based on the observation data, this study determines the design standard of the power-to-weight ratio equal to 8.05kw/t in the south and central area of Shan'xi Province, and the EQ1228V19D2 truck was selected as the longitudinal gradient design typical truck. Based on its technical performance parameters, and the nominal dynamic, kinematic, and operating characteristics of trucks on grades, the highway grade and the truck operating speed as well as the speed along with grade length change rule was studied during trucks climbing upgrades, and climbing performance curves of typical truck with the power-to-weight ratio equal to 8.05kw/t under different grade was accomplished. With the speed loss which allowed and the average operating speed of trucks on near-level grade road section, and based on speed loss in different gradient and grade length, this study also brought forward grade length limit of the road.The climbing lane establishment has mainly been depended on highway capacity and the allowable speed value. Embarked from the truck climbing performance, and based on the climbing performance curves of the truck with the power-to-weight ratio equal to 8.05kw/t, and the allowable speed loss, this study brought forward the condition and index for setting the climbing lane of mountain terrain road.