Evaluation of Left-Turn Lane Offset Using the Naturalistic Driving Study Data

The SHRP 2 Naturalistic Driving Study (NDS) data were used to evaluate the gap acceptance behavior of drivers at left-turn lanes with offsets ranging from –29 ft to 6 ft. The study included 3,350 gaps evaluated (accepted or rejected) by 145 NDS drivers and 275 non-NDS drivers (whose turns were visible from the in-vehicle camera of an NDS driver) at 14 two-way stop-controlled intersections and 44 signalized opposing left-turn pairs. Logistic regression was used to model the critical gap length for drivers as a function of offset, under conditions when their view was either blocked by an opposing left-turning driver or not. The analysis found that the critical gap was longer for negative offsets than for zero or positive offsets, and also longer when sight distance was blocked by an opposing left-turning driver than when it was not. These longer gap lengths can result in decreased operational efficiency of an intersection. Sight distance was much more likely to be restricted by an opposing left-turning driver at negative-offset intersections than at zero- or positive-offset intersections, and drivers at negative-offset intersections were less likely to accept a gap when an opposing left-turn driver was present. An analysis of the shortest post-encroachment times showed that while drivers making left-turns at negative-offset left-turn lanes wait to accept longer gaps, they are, on average, also more likely to leave the shortest amount of time between their turn and the arrival of the next opposing through vehicle, which may present a potential safety concern.

• 
• Supplemental Notes:
  • This paper was sponsored by TRB committee ANB25 Highway Safety Performance.
• Corporate Authors:

  Transportation Research Board

  500 Fifth Street, NW
  Washington, DC  United States  20001
• Authors:
  • Hutton, Jessica M
  • Bauer, Karin M
  • Fees, Chris A
  • Smiley, Alison
• Conference:
  • Transportation Research Board 94th Annual Meeting
  • Location: Washington DC, United States
  • Date: 2015-1-11 to 2015-1-15
• Date: 2015

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: 17p
• Monograph Title: TRB 94th Annual Meeting Compendium of Papers

Subject/Index Terms

• TRT Terms: Automatic data collection systems; Gap acceptance; Highway safety; Left turn lanes; Left turns; Offset intersections; Signalized intersections
• Subject Areas: Highways; Operations and Traffic Management; I73: Traffic Control;

Filing Info

• Accession Number: 01557439
• Record Type: Publication
• Report/Paper Numbers: 15-4794
• Files: PRP, TRIS, TRB, ATRI
• Created Date: Mar 20 2015 3:21PM