A new traffic signal is showing up in Iowa and officials are hoping it’ll clear up confusion many motorists have with left turns across traffic. The Federal Highway Administration has adopted the flashing yellow arrow as a national standard for “permissive left turn” operations.

Cathy Cutler, a transportation planner with the Iowa Department of Transportation, calls it an “enhancement” of the green arrow. “When people are going to make left turns across traffic, they get the green arrow and that means they have the right-of-way to make the left turn. The new addition is what the next phase will be and that’s the flashing yellow arrow. That indicates you can still make a left turn across traffic, but you’re required to yield to any oncoming traffic and any pedestrians,” Cutler says.

Following the flashing yellow arrow, the signal will change to a steady yellow arrow indicating the left turn signal is about to turn red. Cutler says a national study determined drivers found flashing yellow left turn arrows more understandable than traditional yield-on-green indications.

“Really, the confusion came for those left turners when there wasn’t a green arrow. They didn’t really know what the green bulb meant. It means you can proceed but you need to yield to oncoming traffic and pedestrians,” Cutler said. “We believe the flashing yellow arrow will help prevent crashes.”

Several flashing yellows arrow signals are already in operation around Iowa City, Cedar Rapids, Waterloo and Des Moines. More will be installed across the state at busy intersections in the coming months. “The ones that have been up…have been up for a couple months now and we haven’t had any issues or citizen complaints about them,” Cutler said.

The flashing yellow arrows are also expected to reduce traffic delays as the new signals provide traffic engineers with more options to handle variable traffic volumes.


Flashing Yellow Arrow from Iowa DOT on Vimeo.