What is the Justification for a Left-Turn Arrow?
Left-Turn Signal Phasing Left-turn signal phases facilitate left-turning traffic and may improve the safety of the intersection for left-turning vehicles. However, this is done at the expense of the amount of green time available for through traffic and will usually reduce the capacity of the intersection. Left-turn arrows also result in longer cycle lengths, which in turn have a detrimental effect by increasing stops and delays. Pedestrian delays may be increased and due to the increased delay, pedestrians may elect to ignore the pedestrian signals. While phases for protected left-turning vehicles are popular and commonly requested, other methods of handling left-turn conflicts also need to be considered. Potential solutions may include prohibiting left-turns and geometric improvements. Left-Turn Phase Criteria The three left-turn phase criteria presented below are the result of considerable research and study. These three criteria are used in numerous States, including Washington, as
Related Questions
- Does the MUTCD now require agencies to provide a flashing yellow arrow indication for a left-turn movement for the permissive left-turn phase?
- Why do some left-turn arrows allow vehicles to turn only when the green arrow is displayed and not during the through phase?
- Why does the Left-turn Green Arrow or Flashing Advanced Green sometimes work, and other times not?
