Hysteresis Phenomena of a Macroscopic Fundamental Diagram in Freeway Networks
Observations of traffic pairs of flow vs. density or occupancy for individual locations in freeways or arterials are usually scattered about an underlying curve. Recent observations from empirical data in arterial networks showed that in some cases by aggregating the highly scattered plots of flow vs. density from individual loop detectors, the scatter almost disappears and macroscopic relations exist between space-mean network flow and network density. Despite these findings for the existence of well-defined relations with low scatter, these curves should not be universal. In this paper we investigate if macroscopic relations exist for freeway network systems, by analyzing real data from Minnesota’s freeways. The authors show that freeway network systems not only have curves with high scatter, but they also exhibit hysteresis phenomena, where higher network flows are observed for the same average network density in the onset and lower in the offset of congestion. The mechanisms of traffic hysteresis phenomena at the network level are analyzed in this paper and they have dissimilarities to the causes of the hysteresis phenomena at the micro/meso level. The explanation of the phenomenon is dual. The first reason is that there are different spatial and temporal distributions of congestion for the same level of average density. Another reason is the synchronized occurrence of transitions from individual detectors during the offset of the peak period, with points remain beneath the equilibrium curve. Both the hysteresis phenomenon and its causes are consistently observed for different spatial aggregations of the network.
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Availability:
- Find a library where document is available. Order URL: http://worldcat.org/issn/18770428
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Supplemental Notes:
- Abstract reprinted with permission from Elsevier.
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Authors:
- Geroliminis, Nikolas
- Sun, Jie
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Conference:
- 19th International Symposium on Transportation and Traffic Theory
- Location: Berkeley CA, United States
- Date: 2011-7-18 to 2011-7-20
- Publication Date: 2011
Language
- English
Media Info
- Media Type: Web
- Features: Figures; References; Tables;
- Pagination: pp 213-228
- Monograph Title: International Symposium on Transportation and Traffic Theory, 19th
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Serial:
- Procedia - Social and Behavioral Sciences
- Volume: 17
- Publisher: Elsevier
- ISSN: 1877-0428
- Serial URL: http://www.sciencedirect.com/science/journal/18770428/53
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Publication flags:
Open Access (libre)
Subject/Index Terms
- TRT Terms: Arterial highways; Freeway operations; Hysteresis; Loop detectors; Macroscopic traffic flow; Peak hour traffic; Traffic congestion; Traffic data; Traffic density; Traffic equilibrium; Traffic flow
- Geographic Terms: Minnesota
- Subject Areas: Highways; Operations and Traffic Management; Planning and Forecasting; I72: Traffic and Transport Planning;
Filing Info
- Accession Number: 01345360
- Record Type: Publication
- Files: TRIS
- Created Date: Jul 21 2011 10:08AM