Evaluating the Impacts of Unconventional Outside Left-Turn Lane Design on Traffic Operations at Signalized Intersections

This study evaluated the operational impacts of an unconventional outside left-turn lane design used at some signalized intersections in China. Using traffic data collected from 10 approaches to five signalized intersections where both traditional inside and unconventional outside left-turn lanes are installed, the research team compared turning speeds and saturation flow rates for left-turning vehicles from inside and outside left-turn lanes. The team found that vehicles turning from outside left-turn lanes had relatively higher turning speeds than those turning from inside left-turn lanes. The differences in speed were statistically significant for both passenger cars and heavy vehicles. However, the higher speeds did not result in higher left-turn lane capacity. Unconventional outside left-turn lanes provided slightly lower, but generally comparable, left-turn saturation flow rate when compared with traditional inside left-turn lanes. The differences in discharge headways from inside and outside left-turn lanes were not statistically significant. A binary logit model was developed to quantify the impacts of various factors on the probability of a driver selecting the outside left-turn lane to make a left turn. The chance of a left-turning driver choosing the outside left-turn lane would increase with an increase in the traffic volume of the major street and the queue length in the inside left-turn lane and would decrease with an increase in the distance from the upstream right-side side street to the signalized intersection. Drivers of heavy vehicles and those from upstream right-side side streets were more likely to select outside left-turn lanes.

• Record URL:
  https://doi.org/10.3141/2257-07
• Summary URL:
  http://scholar.google.com/scholar_lookup?title=Evaluating+the+Impacts+of+Unconventional+Outside+Left-Turn+Lane+Design+on+Traffic+Operations+at+Signalized+Intersections&author=P.+Liu&author=J.+Wan&author=W.+Wang&author=Z.+Li&publication_year=2011
• Availability:
  • Find a library where document is available. Order URL: http://www.trb.org/Main/Blurbs/166654.aspx
• Authors:
  • Liu, Pan
  • Wan, Jingjing
  • Wang, Wei
  • Li, Zhibin
• Publication Date: 2011

Language

• English

Media Info

• Media Type: Print
• Features: Figures; Photos; References; Tables;
• Pagination: pp 62-70
• Monograph Title: Highway Capacity and Quality of Service 2011
• Serial:
  • Transportation Research Record: Journal of the Transportation Research Board
  • Issue Number: 2257
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Headways; Highway operations; Left turn lanes; Saturation flow; Signalized intersections; Traffic data; Traffic flow
• Uncontrolled Terms: Binary logit models; Lane choice; Turning speed
• Geographic Terms: China
• Subject Areas: Highways; Operations and Traffic Management; I73: Traffic Control;

Filing Info

• Accession Number: 01336881
• Record Type: Publication
• ISBN: 9780309222938
• Report/Paper Numbers: 11-1387
• Files: TRIS, TRB, ATRI
• Created Date: Apr 18 2011 12:24PM