考虑多因素修正的山区二级公路弯坡组合路段小型车运行速度模型

Operating Speed Model of Small Car on Combined Horizontal and Vertical Curves of Mountain Secondary Roads Considering Multi-factor Correction

为确定山区二级公路弯坡组合路段小型车运行速度规律,使用Metro Count 5600设备对国道G108和G244山区二级公路共128.8km的71个特征断面车辆速度进行采集。基于实测数据分析了道路平纵线形及前一个断面车辆初始速度对当前断面运行速度的影响,在初步拟定自变量的基础上,分别采用偏相关分析和因子共线性分析对与因变量相关关系不显著及高度共线性的变量予以剔除,基于非线性回归方法构建曲线中点及曲线出口小型车运行速度预测基础模型;结合山区公路运行环境特点,分别考虑驾驶人视距、路侧静态和动态环境的干扰、交叉口密度对建立的基础预测模型予以修正,最后根据实测数据和预测数据的相对误差对模型进行验证。结果表明:曲线半径、曲线前半段坡度以及曲线入口运行速度对曲线中点运行速度有显著影响;曲线平均半径(当前曲线半径和即将驶入路段半径的平均值)、曲线出口前方坡度和曲线中点运行速度对曲线出口运行速度有显著影响;曲线中点和曲线出口处运行速度实测值和预测值的平均相对误差分别为5.64%和7.35%,模型较为有效。研究结果可为山区二级公路安全性评价及道路设计提供参考。

In order to determine the operating speed rules of small car on combined sections of mountainous secondary roads, Metro count 5600 equipment was used to collect vehicle speeds in 71 feature sections of 128.8 km of G108 and G244 mountain roads. Based on the measured data, the influence of the road horizontal and vertical alignment and the initial velocity of the vehicle in the previous section on the current section operating speed is analyzed. Based on the preliminary formulation of independent variables, partial correlation analysis and factor collinearity analysis are used to eliminate the variables that are not significantly correlated with dependent variables and are highly collinearity. Based on the characteristics of highway operating environment in mountainous areas, the basic prediction model was modified by considering the interference of drivers’ visual distance, static and dynamic environment on the road side, intersection density, and finally the prediction model was verified by using measured data based on relative error. The results show that the radius of curves, slope of the first half of the curve and the velocity at the entrance of the curve have significant effects on the velocity at the center of the curve. The average radius of the curve(the average of the current curve radius and the radius of the incoming section), the slope in front of the curve exit and the operating speed at the middle point of the curve have significant effects on the operating speed at the curve exit. Midpoint and the curve between measured and predicted at the exit of the average relative error of 5.64% and 7.35% respectively, the model is more effective. The results provide reference for secondary highway safety audit and road design in mountainous areas.