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ADOT studies whether yellow lights are too short

Posted at 9:56 AM, Mar 24, 2022
and last updated 2022-03-24 12:56:53-04

PHOENIX — The Arizona Department of Transportation is studying traffic light timing and safety at 10 Valley locations involving highway interchanges or intersections.

ADOT first told ABC15 Investigator Melissa Blasius about the study in November after she analyzed Arizona’s 2020 crash data to find the worst intersections for red-light running crashes.

ABC15’s Time to Stop investigation found six of the eight worst spots for these red-light crashes in Arizona occurred at intersections controlled by ADOT.

See the map below for all eight crash locations:

The ABC15 Investigators also found that yellow light durations in many Valley cities are shorter than what is recommended by the Institute for Transportation Engineers. Several traffic safety groups and research reports indicate longer yellow lights give people more time to stop and can reduce red-light running crashes.

Related: TIME TO STOP: Can longer yellow lights prevent red-light-running crash deaths?

ADOT is currently in the observation stage of its traffic signal study.

The department is monitoring traffic speed, intersection geometry, and driver behavior, according to an ADOT spokesperson. So far, there are no adjustments to the traffic lights themselves.

ADOT identified these 10 locations where data is being collected:

  • The I-10/Warner Road interchange 
  • The I-10/Seventh Avenue interchange 
  • The I-10/Seventh Street interchange 
  • The I-17/Camelback Road interchange 
  • The I-17/Dunlap Avenue interchange 
  • The I-17/Anthem Way interchange 
  • State Route 87/Shea Boulevard intersection 
  • State Route 87/Fort McDowell Road intersection 
  • US 60 (Grand Ave)/91st Avenue intersection 
  • The Loop 101/Peoria Avenue interchange 

ADOT officials say they will consider next steps by late spring to determine whether to field test ITE’s signal timing recommendations.

None of the intersections being studied is a high-crash intersection previously identified by ABC15’s analysis.

Got a news tip? Email ABC15 Investigator Melissa Blasius at and follow her on Twitter and Facebook.