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-  2018 

匝道车道数变化过渡段设计指标
Design index of transition section of ramp lane number change

Keywords: 交通工程,过渡段指标,换道模型,过渡段,仿真模型
traffic engineering
,index section of transition,lane changing model,transition section,simulation model

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Abstract:

为了研究匝道车道数变化过渡段长度和渐变率,参照前人研究成果分析匝道车道数变化过渡段的行车特性,提出利用换道模型研究这2个设计指标的方法。首先建立满足过渡段车辆行驶特征的等速偏移余弦曲线换道模型,并应用德国UMRR交通管理传感器的实测数据证明该换道模型的合理性;然后对该模型中最大横向加速度和最大横向加速度变化率2个关键参数进行深入研究;最后依据该模型,提出基于设计速度的匝道车道数变化过渡段长度和渐变率2个设计指标的推荐值,采用CarSim和TruckSim汽车动力学仿真软件分别建立了小汽车和大货车的仿真模型,利用该模型对提出的推荐值和《公路立体交叉设计细则》(JTG/T D21―2014)(下文简称规范)推荐值进行了对比验证。研究结果表明:基于等速偏移余弦曲线换道模型提出的匝道车道数变化过渡段设计指标,能保证车辆在过渡段沿特定最优轨迹安全、舒适行驶;规范推荐值仅能满足设计速度40 km/h车辆的换道行为,此时的货车最大横向力系数为0.142;当设计速度在40 km/h以下,横向力系数又远低于允许值,过度段长度浪费;当设计速度大于40 km/h时,车辆的横向力系数已经超限,速度达到80 km/h时,横向力系数超限达到315%,车辆在这种状态下行驶不安全。鉴于此,可以推测规范推荐值仅能满足设计速度40 km/h的车辆行驶,高于和低于此速度时,匝道车道数变化过渡段的指标存在不合理性。
In order to study the length and gradual change rate of transition section of ramp lane number change, the driving characteristics of transition section of ramp lane number change were analyzed, and a way to study these two design indexes by using lane changing model was put forward according to the previous research results. Firstly, the lane changing model of constant velocity offset cosine curve satisfying the vehicle running characteristic in transition section was established, and the rationality of the model was proved by using the measured data of UMRR traffic management sensor in Germany. Then two key parameters of the maximum lateral acceleration and the maximum lateral acceleration change rate of the model were studied in depth. Finally, based on this model, the recommended values of design indexes for length and gradual change rate of transition section of ramp lane number change based on design speed were proposed, and simulation models of cars and large trucks were built by using CarSin and TrcukSim vehicle dynamics simulation software, respectively. The proposed values were compared with the recommended values of guidelines for design of highway grade-separated intersections (JTG/T D21―2014) by using this model. The results show that the proposed design index of transition section of ramp lane number change based on the established constant velocity offset cosine curve model can ensure the vehicle to travel safely and comfortably along the specific optimal trajectory in transition section. The standard recommended values can only meet the lane changing behavior of 40 km/h design speed of the vehicle, at this time, the maximum lateral force coefficient of the truck is 0.142. When the design speed is below 40 km/h, the lateral force coefficient is far below the allowable value, resulting in the waste of length of transition section. When the design speed is greater than 40 km/h, the lateral force coefficient of vehicle exceeds the limit. When the

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