Overtaking Lane Setting Conditions and Parameters on Two-Lane Highway in Plateau Mountainous Area
To provide the reference for overtaking lane design on two-lane highway in plateau mountainous area,this article conducts research on the geometric conditions,traffic volume conditions,and length of overtaking lanes on two-lane highways in plateau mountainous areas.The model effectiveness was verified through engineering examples,and the correlation between overtaking lane length and operating speed was studied.First,considering the influence of plateau mountainous conditions,from the perspective of ensuring overtaking vehicle drivers'comfort,the minimum circular curve radius value for overtaking lane on two-lane highway in mountainous areas was given.Second,from the perspective of safe vehicle steering,the maximum uphill and downhill slope conditions for overtaking lane were given.Then,the relation model among traffic conflict time,traffic volume,and design speed of two-lane highway was established.The traffic volume conditions for setting overtaking lane at various design speeds were given.Finally,based on VISSIM simulation experimental data,the model of overtaking lane length on two-lane highway in plateau mountainous area was constructed by using multiple nonlinear regression method.The result indicates that in the plateau mountainous areas,when the design speeds on two-lane highways are 40,60,80 km/h respectively,the road section traffic volume meeting the requirements for setting overtaking lanes should be greater than 318,364,392 pcu/h.The planar circular curve radii should be greater than 610,370,200 m.The maximum longitudinal slopes in the downhill direction are-2.4％,-2.7％,-3.2％respectively.The maximum longitudinal slopes in the uphill direction are 2.6％,3.0％,3.5％respectively.With the same traffic volume,as the length of overtaking lane on two-lane highway increases,the average operating speed of small bus shows the gradually increasing trend.When the length of overtaking lane reaches a certain value,the average operating speed remains at 80 km/h,and no more significant changes will occur.
road engineeringtwo-lane highwaysurface fittingovertaking laneovertaking lane setting condition
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