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通行能力预测是公路设施规划、设计与运营中的基础环节.本文基于埃及曼努菲亚省12条农村双车道路段数据,研究了公路线形等几何特征对通行能力的影响以及线形由切线变为平曲线时通行能力的损失.所选取的路段线形包括直线和随后的平曲线.同时,采集了各路段上车流量及速度数据,利用基于基本图的外推法研究流量和密度关系.路段上不同车型的车辆均转换为小客车当量.此外,针对不同情形(切线、平曲线及对应流量损失),分别建立了最佳回归模型.结果表明,切线型道路的关键自变量是路宽、肩宽以及切线长;平曲线道路的关键变量是曲线半径和路宽.通行能力和几何特征关系最佳模型的自变量为曲线半径.本文的模型可用于分析评价农村双车道道路的通行能力,尤其是评价文中所研究路段的通行能力.
Traffic capacity prediction is the basic link in the planning, design and operation of highway facilities.Based on the data from 12 rural two-lane sections in Manufia, Egypt, the effects of geometric characteristics such as highway alignment on traffic capacity and the change of traffic line from tangent to The loss of traffic capacity when the flat curve is selected.The line shape of the selected road includes the straight line and the following flat curve.At the same time, the traffic flow and speed data of each section are collected and the relationship between the flow and density is studied by extrapolation based on the basic map. In addition, the best regression model is established for different situations (tangent, flat curve and corresponding flow loss) .The results show that the key variables of the tangent road are road width, shoulder Width and tangential length. The key variables of the flat curve road are the curve radius and the road width. The independent variable of the best model of relationship between capacity and geometry is curve radius.The model of this paper can be used to analyze and evaluate the capacity of two-lane rural roads, especially Is to evaluate the passage capacity of the study section.