RULES TO PREVENT YELLOW TRAP

RULES FOR LEFT TURNS PERMITTED ON CIRCULAR GREEN:

• ALWAYS terminate opposite circular greens simultaneously.
• ALWAYS check all possible combinations of phase skip for yellow trap.
• ALWAYS check for yellow trap on the approach opposite to the approach with the left turn signal.
• Check traffic conditions other than left turn phases. Make sure they do not cause yellow trap:
  1. Right turn overlap phases
  2. Reservicing a phase
  3. Ending circular greens simultaneously, but circular yellows end at different times
  4. Starting opposite circular greens at different times (with no turn arrows)
  5. Pre-emptions for emergency vehicles, railroads, lift bridges, and queue discharge
  6. Offset intersections
  7. Intersections with more than 4 legs
• The MUTCD* no longer permits displaying a circular green over the left turn lane.

RULES TO PREVENT YELLOW TRAP WITH FLASHING YELLOW ARROWS

• NEVER end the flashing yellow arrow earlier than the movement the left turns are filtering through.
• NEVER end a flashing yellow arrow while a conflicting right turn overlap continues.
• NEVER allow more than one flashing yellow arrow left turn movement to turn into the same intersection leg.
• NEVER allow a permissive turn across more than one stream of traffic.
• Flashing yellow arrow is not allowed whenever a turning movement and the thru movement share the same lane.
• ALWAYS install a flashing yellow arrow face for any left turn on the approach opposite any approach with a protected left turn.
• Check all possible combinations of phase skip for yellow trap.
• Check traffic conditions other than left turn phases. Make sure they do not cause yellow trap:
  1. Right turn overlap phases
  2. Reservicing a phase.
  3. Pre-emptions for emergency vehicles, railroads, lift bridges, and queue discharge
  4. Offset intersections
  5. Intersections with more than 4 legs

PREVENTING YELLOW TRAP WITH EXCLUSIVELY PERMISSIVE LEFT TURNS:

• Check all possible combinations of phase skip for yellow trap.
• Use the flashing yellow arrows permissive signal (below left) to remove yellow trap from approaches without protected turns.
• Check traffic conditions other than left turn phases. Make sure they do not cause yellow trap:
  1. Right turn overlap phases
  2. Reservicing a phase.
  3. Pre-emptions for emergency vehicles, railroads, lift bridges, and queue discharge
  4. Ending circular greens simultaneously, but circular yellows end at different times
  5. Starting opposite circular greens at different times (with no turn arrows)
  6. Offset intersections
  7. Intersections with more than 4 legs

PREVENTING YELLOW TRAP WITH EXCLUSIVELY PROTECTED LEFT TURNS:

• Check for yellow trap on the approach opposite to the approach with the left turn.
• Check all possible combinations of phase skip for yellow trap.
• Use the flashing yellow arrows permissive signal (below left) to remove yellow trap from approaches without protected turns.
• Check other legs for traffic conditions other than left turn phases. Make sure they do not cause yellow trap:
  1. Right turn overlap phases
  2. Pre-emptions for emergency vehicles, railroads, lift bridges, and queue discharge
  3. Offset intersections
  4. Intersections with more than 4 legs

PREVENTING YELLOW TRAP WITH FLASHING RED ARROWS AND OTHER METHODS:

• Use the rules for flashing yellow arrows when designing flashing red arrows.
• The MUTCD* no longer permits Dallas Phasing, flashing circular yellow, and flashing circular red for permissive left turns.
• Use the rules for flashing yellow arrows with any legacy instances of these prohibited systems too.
• Check for yellow trap on the approach opposite to the approach with the left turn.
• Check all possible combinations of phase skip for yellow trap.
• Check for yellow trap from reservicing a phase.
• Use the flashing yellow arrows permissive signal (above left) to remove yellow trap from approaches without protected turns

PREVENTING YELLOW TRAP DURING CONSTRUCTION:

• Special rules for Preventing Yellow Trap During Construction
• Check for yellow trap on each approach opposite to an approach with the left turn.
• Check all possible combinations of phase skip for yellow trap.
• Use the flashing yellow arrows permissive signal to remove yellow trap from approaches without protected turns.

* MUTCD = Manual of Uniform Traffic Control Devices

SITE LINKS

• All Yellow Trap Links are here:
  YELLOW TRAP INDEX PAGE
• Preventing Yellow Trap During Construction
• Unusual Traffic Problems, Hazards, and Solutions
• Home