Inhomogeneous Flow Patterns in Undersaturated Road Networks: Implications for Macroscopic Fundamental Diagram

Travel conditions on a road network are described by a macroscopic fundamental diagram (MFD) only when traffic is homogeneously distributed over all of the network’s links. Otherwise, a network’s measured traffic states fall beneath its MFD, and network flow therefore falls below the maximum. The present study found that inhomogeneous link flowed in a network may emerge before the beginning of a peak period, even before persistent queues had formed. This finding is potentially problematic because it is known that inhomogeneities of this kind can persist in a network for long durations. Therefore, the inhomogeneities that are predicted for undersaturated traffic conditions may persist as the network moves to the brink of congestion, and even well beyond. If drivers are left to their own devices, a network will never serve its peak period demand at the maximum rate. Steady state conditions in undersaturated networks of signalized intersections were modeled in simple ways. Analyses were performed for an idealized street grid characterized by uniform origin–destination patterns and a more realistic demand pattern that resembles one in downtown San Francisco, California. Emergent patterns in inhomogeneous link flow were examined. Preliminary ideas to combat these undesirable patterns are discussed.

• Record URL:
  https://doi.org/10.3141/2390-08
• Summary URL:
  http://scholar.google.com/scholar_lookup?title=Inhomogeneous+Flow+Patterns+in+Undersaturated+Road+Networks%3a+Implications+for+Macroscopic+Fundamental+Diagram&author=J.+Doig&author=V.+Gayah&author=M.+Cassidy&publication_year=2013
• Availability:
  • Find a library where document is available. Order URL: http://www.trb.org/Main/Blurbs/170347.aspx
• Authors:
  • Doig, Jean C
  • Gayah, Vikash V
  • Cassidy, Michael J
• Publication Date: 2013

Language

• English

Media Info

• Media Type: Print
• Features: Figures; References;
• Pagination: pp 68–75
• Monograph Title: Traffic Flow Theory and Characteristics 2013, Volume 1
• Serial:
  • Transportation Research Record: Journal of the Transportation Research Board
  • Issue Number: 2390
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Network links; Origin and destination; Traffic flow theory; Traffic models
• Uncontrolled Terms: Fundamental diagram; Road networks
• Subject Areas: Data and Information Technology; Highways; Operations and Traffic Management; I71: Traffic Theory; I73: Traffic Control;

Filing Info

• Accession Number: 01476793
• Record Type: Publication
• ISBN: 9780309287159
• Report/Paper Numbers: 13-1371
• Files: TRIS, TRB, ATRI
• Created Date: Mar 27 2013 9:37AM