Guidelines for Exclusive/Permissive Left-turn Signal Phasing

Report No: 85-R19

Published in 1985

About the report:

The objective of this research was to develop guidelines for the use of exclusive/permissive left-turn signal phasing. This was achieved by collecting data on traffic and roadway conditions for exclusive, exclusive/permissive, and permissive left-turn phasings and then analyzing the data to identify relationships between the left-turn phasings and traffic and roadway conditions. The guidelines addressed the following: (1) volume guidelines based on peak hour minimum left-turn volume and the product of the peak- hour left-turn and opposing volumes, (2) annual left-turn accident experience, (3) left-turn traffic conflict experience based on critical number and rates, (4) left-turn delay, and (5) site condition factors identified in the study.

Disclaimer Statement:The contents of this report reflect the views of the author(s), who is responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Virginia Department of Transportation, the Commonwealth Transportation Board, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. Any inclusion of manufacturer names, trade names, or trademarks is for identification purposes only and is not to be considered an endorsement.

Last updated: January 16, 2024

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