I have always wondered this. I have lived in Gilbert and Scottsdale. It doesn't seem to help traffic at all. In fact, I get jammed at the intersection of McQueen and Elliot with people trying to turn East onto Elliot from SB McQueen because the arrow comes after the red light...
Steven C
Favorite Answer
It is to cut down on red light runners.
az_starshine1
It's supposed to be be "safer" than the turn arrow before the green because people aren't trying to run the light. But I think it messes people up more because it's not the same over the whole valley and when you cross from Phoenix to Scottsdale and hit the difference, it just screws people up making it more likely to cause an accident.
♥New Mommy♥
I like the lagging left turn arrows because you can turn left if it's clear (before your left arrow) but if you don't have a chance you still get an arrow at the end of the light cycle.