01556993

Component

In urban transportation networks, the concept of Macroscopic Fundamental Diagram (MFD) expresses a well-defined relation between space-mean flow, density and speed at a network level when congestion is homogeneously distributed. Existence of MFDs in homogeneous network and the effects of traffic heterogeneity on shape of MFDs have been examined in recent studies. In this paper the authors analyse large-scale traffic data in a heterogeneous network with adaptive signal control for the city of Sydney to observe MFDs for different regions of the city. Data contains measurements of volume over green time (VOPT) and a proxy for occupancy named degree of saturation (DS) for different links in the network that utilized by Sydney Coordinated Adaptive Traffic System (SCATS). Firstly, different traffic states are extracted from highly scattered fundamental diagrams of stop-line detectors and a transformation method is proposed to better estimate link densities. Secondly, a clustering algorithm is proposed and extended in a way that is able to deal with networks with missing data, which is a main limit of existing methodologies. In the proposed method, clustering is done without imposing any bias by estimating values for missing data. Furthermore, hysteresis loops are observed for the congested regions of the network after clustering. The classical explanation of spatial heterogeneity does not provide additional insights for the hysteresis, but it is a feature of the control algorithm, which is further elaborated. Based on the results, simple control strategies like perimeter control could be utilized to alleviate the congestion in networks with adaptive signal control.

This paper was sponsored by TRB committee AHB45 Traffic Flow Theory and Characteristics.

01550057

15-2071

English

16p

2015

Transportation Research Board 94th Annual Meeting

Digital/other

Figures; References; Tables

Data analysis; Hysteresis; Intelligent transportation systems; Macroscopic traffic flow; Networks; Traffic data; Urban areas; Vehicle detectors

Sydney Coordinated Adaptive Traffic System (SCATS)

Fundamental diagram

Sydney (Australia)

Data and Information Technology; Highways; Operations and Traffic Management; I73: Traffic Control

Transportation Research Board Annual Meeting 2015 Paper #15-2071

TRIS, TRB, ATRI

Dec 30 2014 12:44PM