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Introducing the flashing yellow left-turn arrow traffic signals

Flashing yellow lightThe flashing yellow left-turn arrow signal is a new traffic management tool aimed at keeping traffic moving, increasing safety and reducing fuel consumption.

You may have already noticed some of the new signals at intersections of Iowa's roads and streets. The new signal features a flashing yellow left-turn arrow, in addition to a red, green and steady yellow arrow.

The flashing yellow arrow replaces the circular green signal used in the traditional left-turn signal configuration to indicate the need for left-turning vehicles to yield to oncoming traffic and pedestrians.

Where are they being used?

The Federal Highway Administration has adopted the flashing yellow arrow as a national standard for permissive left-turn operations. Several such signals have already been installed in Iowa. Others will be installed by the Iowa Department of Transportation and local jurisdictions throughout Iowa as agencies upgrade their traffic signals or make improvements at intersections.
Flashing yellow light drawing
The flashing yellow arrow may be used at any intersection at any time, but the most typical use will be at intersections and time-of-day that have lower traffic volumes, lower traffic speeds and other favorable conditions.


The flashing yellow left-turn arrow is intended to:
  • Help prevent crashes. A national study demonstrated that drivers found flashing yellow left-turn arrows more understandable than traditional yield-on-green indications.
  • Reduce traffic delays. There are more opportunities to make a left turn with the flashing yellow left-turn arrow than with the traditional three-arrow, red, yellow and green indications. This helps reduce delays at intersections, which save time and fuel.
  • Provide more traffic management flexibility. The new traffic signals provide traffic engineers with more options to handle variable traffic volumes.

How does a flashing yellow left-turn arrow work?

A flashing yellow arrow means left turns are permitted, but you must first yield to oncoming traffic and pedestrians, and then proceed with caution. The flashing yellow arrow does not replace the solid yellow arrow and its meaning; it does replace the green "ball" indication as a signal for a yielding left turn.

Flashing yellow light drawing
Drivers should always remember: a flashing yellow arrow means turn with caution. Oncoming traffic has a green light.

How should drivers approach a flashing yellow left-turn signal?

Drivers should stop at the intersection and yield to oncoming traffic. If, and when, it is safe, make your left turn and proceed through the intersection. When the available time for the flashing yellow arrow ends, the solid yellow left-turn arrow begins. The solid yellow retains it standard meaning the left turn signal is about to go to red, so you must prepare to stop or complete your left turn if already in the intersection.

Here's what the new signals look like and mean.

The flashing yellow arrow traffic signals consist of four arrow lights that are used exclusively for left-turning traffic. The arrow traffic signals are separate from the traffic signals containing the circular "ball" lights for through traffic.

Red arrow

Steady red arrow:
Drivers turning left must stop and wait.

Yellow arrow

Steady yellow arrow:
The left-turn signal is about to turn red. Do not enter the intersection if you can stop safely. Complete your left turn if you are already within the intersection

 Flashing yellow arrow

Flashing yellow arrow:
 Yield to oncoming traffic and pedestrians; then turn left proceeding with caution. Oncoming traffic has a green light.

Green arrow

Steady green arrow:
Drivers can proceed with the left turn. Oncoming traffic must stop. Do not go straight.