Some Properties of Flows at Freeway Bottlenecks
Capacity of a freeway segment should only be measured when it is an active bottleneck. The properties of flows at active freeway bottlenecks bear on both the definition of capacity and the procedure of capacity analysis. Past studies have examined the flow features at bottlenecks on several freeways in Toronto, Ontario, and San Diego, California. This study examined twentyseven active bottlenecks in the Twin Cities metro area, Minnesota, for a seven-week period. The analysis focuses on the properties of pre-queue transition flows (PQF) and queue discharge flows (QDF) averaged across various time intervals (thirty-second, daily average, and long-run average). It is found that the percentage flows drop after upstream queues form at all studied bottlenecks range from 2 percent to 11 percent. The 30-second QDFs display high variation and should not be assumed to be constant. The daily average QDFs at each studied bottleneck follows a normal distribution based on two normality tests and visual inspection of the normal probability plot. Results also suggest that the long-run average QDFs (mean 2016 pc/ln/hr) and PQFs (mean 2124 pc/ln/hr) are both normally distributed. The implication of these empirical findings on capacity estimation is also discussed.
|Date of creation:||2004|
|Date of revision:|
|Publication status:||Published in Journal of the Transportation Research Board No. 1883 122-131.|
|Contact details of provider:|| Postal: |
Phone: +01 (612) 625-6354
Fax: +01 (612) 626-7750
Web page: http://nexus.umn.edu
More information through EDIRC
Please report citation or reference errors to , or , if you are the registered author of the cited work, log in to your RePEc Author Service profile, click on "citations" and make appropriate adjustments.:
- Zhang, Lei & Levinson, David, 2010.
"Ramp metering and freeway bottleneck capacity,"
Transportation Research Part A: Policy and Practice,
Elsevier, vol. 44(4), pages 218-235, May.
- Cassidy, Michael J. & Bertini, Robert L., 1999. "Some traffic features at freeway bottlenecks," Transportation Research Part B: Methodological, Elsevier, vol. 33(1), pages 25-42, February.
When requesting a correction, please mention this item's handle: RePEc:nex:wpaper:bottleneckproperties. See general information about how to correct material in RePEc.
For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: (David Levinson)
If references are entirely missing, you can add them using this form.