Empirical Analysis of Traffic Bottleneck at Beijing Expressways.

The expressways in Beijing are confronted with more serious traffic congestions. Based on the survey data obtained fromthe typical sections at the expressways, the time dependent characteristics of traffic flow parameters were analyzed in detail and the data gap was found in this paper. The Fast Fourier Transform (FFT) method is proposed to transfer the data of traffic flow parameters for describing the fluctuation characteristics of traffic flow. Two methods of identification, the graph method and the control line method, were proposed as to the change time of traffic bottleneck forming and dissipating. The findings in this paper have already been applied in traffic management and ramp control at the expressways in Beijing. [ABSTRACT FROM AUTHOR]