Flashing yellow arrows

The flashing yellow arros on traffic signals solve a problem that circular green lighs can not. The problem is called yellow trap.

When a traffic signal shows a circular green in both directions, left turns can filter through gaps in oncoming traffic. But what happens if one directions turns yellow and red, so the other direction can have a green turn arrow?

If circular greens are used, a car waiting to turn left will turn when the light turns yellow, across oncoming traffic that still has a green light. CRASH!

If a flashing yellow arrow is used, it can continue to flash yellow while the other signals facing the same way are red. This delays the left turn until a gap appears, or until the oncoming traffic gets a yellow light.

Thanks for this explanation. I’ve been losing sleep over this issue for years now.


No,-- laws and procedures are already in place.
The car waiting to turn left sees the same yellow light that the oncoming traffic sees. The biggest mis-understanding of the rules is that the car waiting to turn left, out in the center of the intersection, has the right-of-way to finish the left turn AFTER the light changes red.
It’s those yellow light runners AND the hurry up left turners TOGETHER that cause accidents.
An exaple to illustrate ; The car waiting ( out in the center of the intersection, not back behind the line ), facing west, is not running the west bound red light, but is actually first in line for the south bound green as he finishes his left turn.
Way too many people forget how to take their turn when waiting to turn left.

I’ve never seen a flashing yellow left turn arrow used in conjunction with a solid red light facing the same way. I hope I never do.

What state is using this?

I think that they should make the red lights purple, so that people don’t feel as bad that they have to stop.

Neither have I. Only time I’ve EVER seen a flashing yellow is when it’s flashing by itself as a caution. This is totally new to me.

That’s the way that I learned to do it. Unfortunately, many don’t seem to get it.

you’re supposed to stop at the red lights? No wonder people keep waving at me with one finger…

IMHO, this is a solution in search of a problem. The signal in question is almost always the dedicated left turn signal. It is for the turn lane(s) only. So a yellow arrow isn’t necessary if it is dedicated for the turn lane only. Also, the majority of these signals are synchronized with the signals in the opposite directions, and the ones that are not synchronized can solve this problem by having all the lights in both directions turn yellow and red at the same time. Besides, in intersections where this is necessary (where there is a combination signal for both turning and straight lanes), they already have yellow and red arrows.

Wrong. The yellow trap problem has been around for years. The usual cure for it has been to put the left turn arrows before the straight ahead circular greens. But that doesn’t fix the problem, for these reasons:

  1. The hazard reappears if there is no traffic on the crossroad, and the signal skips the green light for it because the detectors are empty of cars.

  2. The only other fix is to make the left turns exclusively protected. This means that the left turn is stopped by a red light any time the green arrow is not on. This reduces the capacity of the intersection.

  3. Progression of green lights from one intersection to another is much easier to achieve if some signals can put the left turn in one direction after the circular green in the other direction. Restricting the left turns to be before the circular greens often prevents signal progression on two-way streets.

  4. If a left turn has a green arrow for one direction, but no green arrow is installed in the opposite direction, yellow trap occurs any time the green arrow follows the opposing green, whether it occurs by design or due to skipping of cross street greens.

  5. Yellow trap also occurs when a signal is preempted for an emergency vehicle or a railroad, and turns green in only one of the four directions.

I did a survey of my city’s signals, and over half of them can cause yellow trap. Most of them are not designed to do this, but do it when the cross street greens are skipped at night, when traffic demand is low. This is the cause of many unexplained left turn accidents at night. One signal was yellow trapping drivers on every cycle at night, because the left turn signal is not actuated (no left turn lane available), but the cross street does have detectors. It was the intersection with the highest number of accidents, and the city didn’t know why, until I told them. They fixed it by not displaying the green arrow unless the cross street green had also been displayed.

Flashing Yellow Arrows is now in the process of being added to the US Department of Transportation’s “Manual of Uniform Traffic Control Devices.” It will soon be the standard signal, replacing the 5-light “doghouse” left turn signal. It will have 4 lights.

A red arrow for stop
A steady burning yellow arrow for clearance
A flashing yellow arrow for turns permitted through gaps in opposing traffic.
A green arrow for protected left turns.

Google “flashing yellow arrows” and “yellow trap” for more on this hazard.

I hope you do, because it is much safer.

States currently installing Flashing Yellow Arrows at new and rehabilitated signals:

Washington, Oregon, California, Nevada, Arizona, Colorado, Idaho, Michigan, Louisiana, North Carolina, Florida.

States using flashing red arrows or flashing circular red for permissive left turn:

Michigan, Delaware, California.

Whew! No Ohio on there, I guess I am safe. In most places when a new regular light or stopsign is places people get confused or ignor it, if something entirely new comes there will probably be accidents because of it.

You left out Texas, just started seeing them.

I just love it when someone tells me my opinion is wrong. We are not debating facts here. We are debating points of view and neither is wrong.

You would think I would have witnessed this “trap” as a driver if it were really an issue, especially when I was towing a 53’ trailer through 38 states. Perhaps I am simply too well trained to fall into a trap that should be resolved by the most basic driver’s education. Simply put, if traffic hasn’t stopped, don’t pull into the intersection. How hard is that? Aren’t drivers taught to look for people who might run the red light (when the oncoming signal is red)? Why is this any different?

Okay, I have looked it up, and according to Wikipedia, the simple explanation is “The yellow trap is a potentially-dangerous scenario in traffic flow through a traffic light relating to permissive left turns. It occurs when a yellow light is displayed while, at the same time, oncoming traffic still has a green light, causing drivers to complete their left turn on yellow when it is not safe to do so.” Shouldn’t licensed drivers know it isn’t safe to make the turn if cars are still approaching?

The solutions seem simple. One solution is to train drivers to yield to oncoming traffic and not pull out unless it is clear or oncoming traffic has stopped. Oh, wait! We already do that. The other solution is don’t program lights to do that. If there is a green arrow, oncoming traffic should be stopped already. If there isn’t an arrow, don’t let the turning vehicle’s light cycle to red while the opposite direction still has a green light. Just make this “yellow trap” illegal and the problem is solved.

Honestly, as a former professional driver and an avid road tripper, I have never faced this issue and IMHO, there are much bigger fish to fry.

Again, these are just my humble opinions being expressed.

Driver training is the key here. Not more redundant laws nor babysitting overkill technology.
And it’s not small fete to get this neccessary training into the mainstream. Training new drivers and re-training existing drivers is a massive undertaking. We can’t afford to ?? We can’t afford NOT to.
Accident rates would go down, insurance rates would go down, and traffic would flow.
I’ve posted here before that if we learned to drive as we are trained to fly then most of these driver knowledge issues would be covered.

Texas has also started using cameras to catch red light runners. I wish they would do that in all 50 states.

All good ideas have a trade off. Intersections with red light cameras have a higher accident rate. Those intersections are marked with signs alerting there is a camera so often what happens is as soon as a light turns yellow, people SLAM on the brakes and rear end accidents are increased. Also, when a construction worker waves a person on through a red light, that person can get a ticket, although some of those tickets are forgiven.

Is the red light camera the problem or is tailgating the problem? In my opinion we shouldn’t forgo the red light camera just for tailgaters. I can’t tell you how many times I see people run red lights here in Florida. I believe it would reduce collisions, and I refuse to call rear end collisions “accidents.” There is nothing accidental about the decision to tailgate.

IMOO it is tailgaters and paranoid people who slam instead of braking normally. Everbody thinks it will reduce accidents but it does not.