CRITICAL MOVEMENT ANALYSIS FOR SHARED LEFT TURN LANES

This paper analyzes critical movements for left turn lanes that are shared by through traffic. It shows that the critical conflict volume along a given approach is the sum of the left turns, the opposing traffic, and the blocked proportion of the through traffic in the shared lane. A set of impedance or blockage factors is derived as a function of the left turns per cycle. When two left turns per cycle occur, 60 percent of the through vehicles in the lane are blocked. When five left turns per cycle exist, 80 percent of the through vehicles in the shared lane are blocked. Thus, for all practical purposes, five or more left turns per cycle will pre-empt the shared lane. From this it follows that short signal cycles are desirable where shared left turn lanes predominate. The paper addresses shared lanes in both single and multilane approaches. It contains guidelines for computation of critical movement volumes in practice.

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/trr/1988/1194/1194-019.pdf
• Record URL:
  https://scholar.google.com/scholar_lookup?title=CRITICAL+MOVEMENT+ANALYSIS+FOR+SHARED+LEFT+TURN+LANES&author=H.+Levinson&publication_year=1988
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/030904765X
• Supplemental Notes:
  • This paper appears in Transportation Research Record No. 1194, Traffic Flow Theory and Highway Capacity. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
• Authors:
  • Levinson, Herbert S
• Publication Date: 1988

Media Info

• Features: Figures; References; Tables;
• Pagination: p. 167-178
• Monograph Title: Traffic flow theory and highway capacity
• Serial:
  • Transportation Research Record
  • Issue Number: 1194
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Calculation; Critical values; Electrical impedance; Guidelines; Lane occupancy; Left turns; Mechanical impedance; Motor vehicle operations; Opposing traffic; Through traffic; Time; Traffic lanes; Traffic signal cycle; Traffic volume
• Uncontrolled Terms: Computation
• Old TRIS Terms: Shared lane operations; Time effects
• Subject Areas: Highways; Operations and Traffic Management; I71: Traffic Theory;

Filing Info

• Accession Number: 00489681
• Record Type: Publication
• ISBN: 030904765X
• Files: TRIS, TRB, ATRI
• Created Date: Nov 30 1989 12:00AM