Extended Bottlenecks, the Fundamental Relationship, and Capacity Drop on Freeways

This paper presents evidence that the commonly used point bottleneck model is too simplistic for freeway bottlenecks, the actual mechanism appears to occur over an extended distance. The authors find evidence of subtle flow limiting and speed reducing phenomena more than a mile downstream of a lane drop bottleneck. These phenomena impact the fundamental relationship (FD). Close to the lane drop the free flow regime appears to come from a "parabolic" FD, but further downstream the relationship straightens to a "triangular" FD and throughput increases. The authors develop a theory to explain the underlying mechanisms. These insights should help resolve the decades long debate about the shape of the FD. The phenomena also provide a mechanism that may contribute to the empirically observed capacity drop often seen at bottlenecks. Although the authors study a lane drop, this work should be transferable to other bottlenecks where the capacity restriction persists for an extended distance, e.g., a corridor with a fixed number of lanes and an on-ramp bottleneck.

• Record URL:
  http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B9853-52X1TRD-J-1&_cdi=59087&_user=10&_pii=S1877042811010664&_origin=browse&_coverDate=12%2F31%2F2011&_sk=999829999&view=c&wchp=dGLbVzW-zSkWz&md5=cf42d71193d860ee0f14705d77f71399&ie=/sdarticle.pdf
• 
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/18770428
• Supplemental Notes:
  • Abstract reprinted with permission from Elsevier.
• Authors:
  • Coifman, Benjamin
  • Kim, SeoungBum
• 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 44-57
• Monograph Title: International Symposium on Transportation and Traffic Theory, 19th
• Serial:
  • Procedia - Social and Behavioral Sciences
  • Volume: 17
  • Publisher: Elsevier
  • ISSN: 1877-0428
  • Serial URL: http://www.sciencedirect.com/science/journal/18770428/53
• Publication flags:

  Open Access (libre)

Subject/Index Terms

• TRT Terms: Bottlenecks; Freeway operations; Highway capacity; Lane changing; Lane drops; On ramps; Traffic density; Traffic flow
• Uncontrolled Terms: Free flow (Traffic)
• Subject Areas: Highways; Operations and Traffic Management; I72: Traffic and Transport Planning;

Filing Info

• Accession Number: 01345330
• Record Type: Publication
• Files: TRIS
• Created Date: Jul 21 2011 10:08AM