基于停车视距的高速公路最小圆曲线半径研究

Study on Minimum Circular Curve Radius of Expressway Based on Stopping Sight Distance

停车视距作为影响行车安全的重要因素,是公路设计中的强制性控制指标之一。曲线路段中央分隔带防眩设施和路侧护栏、边坡等均可能限制驾驶人的视线,导致停车视距不足。根据《路线规范》中现有高速公路横断面组成及其宽度,采用无人机采集了3条不同设计速度、不同横断面类型的高速公路不同车道内不同车型的横向位置视频,采用图像等比例的分析方法,提取了车辆横向位置数据后,采用统计分析的方法,得到了85%位的高速公路不同车道内不同车型驾驶人视点横向位置,进而确定了填方、挖方、隧道3种路段不同车型和偏向情况下的横净距。基于《路线规范》停车视距,考虑不同曲线偏向时视线受影响最不利车道与车型,根据曲线路段停车视距与横净距和圆曲线半径之间的几何关系,推导了曲线路段满足通车视距的最小圆曲线半径计算公式,并提出了填方、挖方、隧道,这3种路段曲线右偏与左偏两种情况下满足停车视距的圆曲线最小半径指标建议值。结果表明:对右偏圆曲线,《路线规范》中规定的圆曲线最小半径一般值能满足小客车的停车视距要求,也能满足曲线隧道内纵坡大于3%时货车停车视距,但不满足下坡或纵坡小于等于3%时货车停车视距;对左偏曲线,不满足小客车和大货车的停车视距,应取《路线规范》规定的圆曲线最小半径一般值的1.8~2.25倍。

As an important factor affecting driving safety, stopping sight distance is one of the mandatory control indicators in highway design. Anti-dazzle facilities, side guardrails, side slopes, etc. in the medium separation area of curved road sections may restrict the driver’s line of sight, resulting in insufficient parking sight distance. According to the cross-section composition and width of existing expressway in Alignment Specification, the lateral position video data of different vehicles in different lanes of 3 expressways with different design speeds and different cross-section types are collected by using UAV. After extracting the vehicle lateral position data by using the image equal proportion analysis method, the viewpoint lateral positions of V85 of different vehicle types in different lanes of expressways are obtained by using the statistical analysis method, and the lateral clear distances under different vehicle types and deflection direction conditions of sections of filling, excavation and tunnel are determined. Based on the stopping sight distance in Alignment Specification, considering the most unfavorable lanes and vehicle types when the line of sight is affected by different curve directions, according to the geometric relationship of stopping sight distance with horizontal clear distance and circular curve radius of the curved road section, the calculation formula of the minimum circular curve radius for the curved road section to meet the traffic sight distance is derived. The result shows that(1) for the right circular curve, the generally minimum radius of the circle curve specified in Alignment Specification can meet the stopping sight distance of passenger cars, and can also meet the stopping sight distance of trucks when the longitudinal slope in the curve tunnel is greater than 3%, but it cannot meet the stopping sight distance of trucks when the longitudinal slope is less than or equal to 3%;(2) for the left circular curve, it cannot meet the stopping sight distances of passenger cars and trucks, it should be 1.8-2.25 times of the general minimum radius of the circular curve stipulated in Alignment Specification.