交通流速度-密度模型特性分析

Analysis of Characteristics of Traffic Flow Speed-density Relation Model

描述交通流流量、速度和密度关系的基本图是交通流理论与交通工程领域的基础模型之一。本文通过对10种典型的速度-密度模型的总结分析,采用北京快速路实测数据时上述模型进行参数标定与误差分析。结果表明,速度-密度模型的拟合误差在不同的数据集下不会发生很大的变化;如自由流速度、阻塞密度等具有明确物理意义的参数会随着不同数据集合发生较大的变化;Newell模型和Logisitic模型在不同的数据集下都表现出良好的稳定性。上述研究将为速度-密度模型结构优化、模型参数标定提供实践支撑。

The fundamental diagram, as the graphical representation of the relationships among traffic volume, speed and density, has been the foundation of traffic flow theory and transportation engineering. By summarizing and analyzing 10 typical speed-density relationship models, parameter calibration and error analysis of the above models are done using measured data of Beijing expressway. The result shows that （ 1 ） the fitting errors of speed-density models have less change under different sets of field data; （2） some physical meaningful parameters, such as free-flow speed and jam density, have great difference under different sets of field data; （3） Newell model and Logisitic model show good stability under different sets of field data. The above research will provide practical support for optimization of structures of speed-density relationship models and calibrations of model parameters.