AVERAGE TIME GAPS IN CONGESTED FREEWAY FLOW

This paper examines characteristics of average time gaps between vehicles in congested freewasy traffic flow. Such characteristics can provide an important link between microscopic and macroscopic traffic flow. The gaps between individual pairs of vehicles are a microscopic phenomenon, but average time gaps can easily be determined from commonly collected macroscopic traffic flow data. Data derived from the San Diego ramp metering system and the traffic surveillance system on the Queen Elizabeth Way in Ontario, Canada are analyzed to demonstrate the characteristics of average time gaps. It is shown that average time gaps in congested flow are approximately constant with respect to speed over most of the congested flow regime. Average time gaps also vary considerably between lanes at a single location and from site to site for the same lane. They display considerable scatter, which probably reflects even greater scatter in the underlying individual time gaps. At some sites and times of day, there is either no change or a slight reduction in average time gaps at the onset of congestion, while in other cases, a definite increase in average time gaps coincides with flow breakdown as indicated by the time series of speed. No easy explanation for the variability of average time gaps is discovered, but differences in driver populations may be one factor.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/09658564
• Corporate Authors:

  Elsevier

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  Kidlington, Oxford  United Kingdom  OX5 1GB
• Authors:
  • Banks, J H
• Publication Date: 2003-7

Language

• English

Media Info

• Features: Figures; References;
• Pagination: p. 539-554
• Serial:
  • Transportation Research Part A: Policy and Practice
  • Volume: 37
  • Issue Number: 6
  • Publisher: Elsevier
  • ISSN: 0965-8564
  • Serial URL: http://www.sciencedirect.com/science/journal/09658564

Subject/Index Terms

• TRT Terms: Freeways; Macroscopic traffic flow; Microscopic traffic flow; Ramp metering; Traffic characteristics; Traffic congestion; Traffic flow; Traffic lanes; Traffic speed; Traffic surveillance
• Uncontrolled Terms: Time gaps
• Geographic Terms: Ontario (Province); San Diego (California)
• Subject Areas: Highways; Operations and Traffic Management; I71: Traffic Theory;

Filing Info

• Accession Number: 00943534
• Record Type: Publication
• Files: TRIS, ATRI
• Created Date: Jun 9 2003 12:00AM