基于累积流量比里程分布的区域交通状态评价

Evaluation of Regional Traffic Status Based on VKT Distribution of Accumulative Volume Ratio

准确地交通状态研判结果是有效地进行交通拥挤控制的前提和依据。以成都市金牛区二环路、人民北路二段、一环路、沙湾路围合成的局域路网为例,引入宏观基本图理论,建立了不同交通状态下路段累积流量比的里程分布模型,设计了基于路段累积流量比里程分布的区域交通状态指数(RTSI)。首先,利用宏观基本图理论,将区域交通状态划分为畅通、基本畅通、轻微拥挤、中度拥挤和严重拥挤5个等级并对各等级对应的累积流量比阈值区间进行了划分。然后,利用交通仿真数据,对城市区域路网上累积流量比的里程概率分布分别进行了统计及4种常用分布拟合,根据拟合结果建立了区域路网累积流量比累积里程分布模型。最后,通过关联宏观交通流状态与路段累积流量比累积里程分布,借鉴交通工程中最高限速的取值依据,构造了基于累积流量比里程分布的区域交通状态指数评价模型。实例分析表明:RTSI与北京交通发展研究中心提出的TPI契合程度达85%以上,充分证明了RTSI的有效性;同时,TRSI集成了网络中所有路段的累积流量比,其变化过程是连续的,避免了TPI指数的骤增和骤减的情况,因此其变化趋势对交通拥挤发生、发展、蔓延及消散过程的描述更贴近于实际,具有更好的适用性。

An accurate evaluation of traffic status is the precondition and basis for effective congestion control. Taking a regional road network formed by 2 nd Ring Road, 2 nd Section of North Renmin Road, 1 st Ring Road and Shawan Road in Jinniu District of Chengdu for example, by introducing the theory of macroscopic fundamental diagram(MFD), the VKT distribution model of accumulating volume ratio under different traffic conditions is established, and the regional traffic status index(RTSI) based on VKT distribution of AVR is developed. First, the regional traffic status is divided into levels of free-flow, near-free-flow, slight congestion, moderate congestion and severe congestion based on the theory of MFD,and the corresponding AVR threshold intervals of different traffic statuses are divided as well. Then, based on the traffic simulation data, the VKT probability distributions of AVR of regional road network are accounted and 4 common distributions are fitted respectively, and the accumulative VKT distribution model of AVR of regional road network is established accordingly. At last, by associating the macroscopic traffic status with the accumulative VKT distribution of AVR of the road sections and referring the gist of maximum speed limitation in traffic engineering, the RTSI evaluation model based on VKT distribution of AVR is developed. The example analysis shows that(1) the fitting degree of RTSI and TPI proposed by Beijing Transportation Development Research Center is more than 85%, which proved the effectiveness of RTSI;(2) as the RTSI integrated the AVRs of all the sections, its changing process is continuous, which avoided the sudden increase and decrease of TPI, so its variation trend is more realistic for describing traffic congestion occurrence, evolution, spreading and evacuation process with better applicability.