互通立交单车道入口小客车运行速度模型

Operating speed model of passenger car at single-lane entrance of interchange

为了确定高速公路互通式立交单车道入口小客车运行速度特征,计算小客车在高速公路互通式立交入口处的运行速度模型,确保车辆在衔接段运行速度之间的协调,使车辆安全运行,在分析高速公路互通立交单车道入口处小客车运行速度实测数据基础上,得出小客车在入口处运行规律。使用链式开普勒雷达测速仪对入口处小客车速度进行实时采集,选取8条匝道特征点(合流鼻、合流点以及加速车道终点)处自由流状态下小客车速度作为分析样本,采用K-S检验对所取样本进行正态分布检验,在满足检验要求并分析三角区段和加速换道段速度及加速度特性后,确定自变量参数。最后利用SPSS软件进行回归分析,分别建立了小客车在合流点及加速车道终点处运行速度预测模型,并用4条匝道对模型进行了验证。研究结果表明:合流点处车辆运行速度与合流鼻速度及三角区段长度呈正相关,与平曲线半径倒数呈负相关;加速车道终点处运行速度与合流鼻速度及加速换道段长度呈正相关,与平曲线半径倒数呈负相关;模型通过了回归等式及回归参数显著性和平均相对误差检验,模型预测值与实测值相对误差平均值均小于10%,所建模型满足精度要求。研究结果对《公路项目安全性评价规范》(JTG B05—2015)中车辆运行速度相关规定进行补充说明,为高速公路安全性评价及设计提供理论支撑与参考。

The aim of this study was to determine the characteristics of a car’s operating speed at a single-lane entrance of an interchange,and to calculate a running speed model of cars at the entrance of a freeway interchange,to ensure coordination of operating speed in the convergencesection for improved vehicle safety.Based on the analysis of the measured data of passenger cars at the entrance of a single lane at an expressway interchange,the law of operation of a passenger car at the entrance was obtained.The speed of the passenger car at the entrance was collected in real time.The chain Kepler radar velocimeter was used to collect vehicle speed at entrance in real time.The feature points（including the starting point of the tapered section,diversion point,and the small nose point）of eight ramps were selected as the analysis sample for vehicle speed in the free-flow state.The K-S test was used to test the normal distribution of the samples.When the K-S test requirement was met,the speed and acceleration characteristics in the tapered section and deceleration section were analyzed,and the parameters of the independent variables were determined.Finally,SPSS software was used to perform the regression,and the operation speed prediction model of the passenger cars at the diversion point and the small nose points was developed.Then,the model was verified using data from four ramps.The results show that the running speed at the junction point is positively correlated with the velocity of the converging nose and the length of the triangle section,but negatively correlated with the reciprocal of the horizontal curve radius.The running speed at the end of the acceleration lane is positively correlated with the velocity of the converging nose and the length of the acceleration lane,but negatively correlated with the reciprocal of the horizontal curve radius.In addition,the predicted model was successfully tested using a regression equation,regression parameters,and average relative error checking.The relative error in the predicted value and measured value is less than10%.The established regression model met the precision requirements.The results of the study are a good supplementary explanation of the relevant regulations of running speed of the standards in Guidelines for Safety Audit of Highway（JTG B05-2015）.This study provides theoretical support and references for expressway safety evaluation and design.9 tabs,4 figs,23 refs.