Abstract: In order to analyze the complex characteristic of traffic flow on expressway, multifractal detrended fluctuation analysis method have adopted to calculate the general hurst index of traffic flow time series. The result show that the capacity time series and speed time series are multifractal, capacity time series has more fluctuation than speed time series. The general hurst indexes of rearranged time series which disrupt the order of original series have been calculated, the rearranged general hurst indexed are not 0.5 and far smaller than the original series, then, the multifractal characteristic most decide by the long distance relevance, and has certain relation with the probability density.

Key words: multifractal, multifractal detrended fluctuation analysis, traffic flow time series, general hurst index

摘要： 采用多重分形消除趋势波动分析法研究城市快速路交通流的多重分形特征。首先，计算和比较了实测的流量和速度序列的广义hurst指数，结果表明：流量序列和速度序列均呈现多重分形，且流量序列的波动程度强于速度序列。然后，对两种序列的重排序列的计算结果显示，重排序列的广义hurst指数远小于原序列且不为0.5，说明交通流的多重分形特征主要由序列的长程相关性决定，同时与概率分布有关。

关键词: 多重分形, 多重分形消除趋势波动分析, 交通流时间序列, 广义hurst指数