城市车路协同系统下实时交通状态评价方法

交通状态评价方法能够为交通管理系统提供可量化的实时路网信息，为动态引导交通流、缓解交通拥堵提供依据。受限于交通路网的时变性和评价过程的主观性，目前传统评价方法的精度时常无法满足需求。基于城市车路协同系统动态获取路网信息优势，提出一种利用车路信息融合的实时交通状态评价方法。首先，定义了一种网联汽车与路侧终端间的无线交互方式，并确定数据协议以保证实时车辆数据的准确性；其次，从实时数据中选取平均通过时间、平均停车次数、平均停怠时间作为一级评价指标进行模糊综合，应用多算子对计算的一级评价结果构成二级交通状态评价指标，并根据层次分析法确立指标权重，同时根据仿真和试验结果建立适用于各级道路参数的可变隶属度规则，从而融合动态车辆数据与静态路段参数，计算得出交通状态评价结果与评分；最后，由网联汽车、车载终端、路侧终端和无线通信模块搭建实际协同测试系统对该方法进行了试验验证。试验结果表明：测试系统所得到的路段实时交通状态评价得分与对应的交通状态变化趋势一致，能够准确体现城市车路协同环境下的交通状态特点。该评价方法运用信息融合方法提高了交通状态评价结果的实时性与客观性，同时为车路协同技术应用于实时交通诱导，缓解城市交通拥堵提供了理论依据。

Real-time Traffic Status Evaluation Method for Urban Cooperative Vehicle Infrastructure System

To guide traffic flow dynamically and alleviate traffic congestion, real-time traffic status evaluation methods can provide traffic management systems with quantifiable dynamic road network information. Owing to the time-varying characteristics of traffic networks and the subjectivity of the evaluation process, the accuracy of traditional evaluation methods has not been achieved. With the advantage of acquiring road information dynamically in an urban cooperative vehicle infrastructure system (CVIS), a novel real-time traffic status evaluation method using vehicle and infrastructure information fusion was proposed. First, a method for wireless interaction between connected vehicles and road side units was identified, and an improved data protocol was established to ensure the accuracy of real-time vehicle data. Second, the average travel time, average number of stops, and average stop time were selected as first-level evaluation indexes of a fuzzy comprehensive evaluation. Then, the first-level evaluation results calculated by the multi-operator were used to establish the second-level traffic state evaluation indexes, and the index weights were determined according to the analytic hierarchy process. Meanwhile, according to the simulation and experimental results, a variable membership rule for all levels of road parameters was established, which combined dynamic vehicle data with parameters of static road sections, and the final traffic evaluation scores were calculated. Finally, an actual urban CVIS system was developed to test the reliability of the real-time traffic status evaluation method. The experimental results show that the real-time evaluation scores were consistent with the corresponding trend of real traffic status, thus, accurately reflecting real-time traffic status in an urban CVIS. The proposed method improved the real-time capability and objectivity of the traffic status evaluation results; furthermore, it can be used to provide a theoretical basis for the application of a CVIS in guiding real-time traffic and alleviating urban traffic congestion.