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So it acts much like a flashing red light but you don't have to stop (hardly any one does, at least in Metro Detroit...), just yield? While I like the innovation, I think it's sort of pointless.

Yeah- you can turn when it's clear.


I see it both ways.... there are certainly times when I clearly see the traffic is clear and I could safely turn, but can't because I'm waiting for the green light.

I *do* think this is already accomplished well enough by intersections that have the protected left under the standard lights...
Red, Yellow,Green (solid), Green (arrow). When you just see the green, you yield and turn when safe.

This is just an extension of this... which does lead to the other side of things. I see your "pointless" side of it as well. We do already have enough ways to accomplish this already. And I'm not sure what another sign to memorize does for overall driving safety, but I can see it being possible that this might confuse or be misunderstood. Like the old joke/addage: "Green is go, red is stop, and yellow is 'hurry up'" Flashing mean REALLY hurry up

Anonymous writes:

We have flashing turn signals here in Australia, but they are mostly used for intersections where there are lots of pedestrians. What it means is yes, you can go and take the turn, but you have to give way to the pedestrians. They usually kick in the second half of the pedestrian "cross now" green cycle (when it starts blinking, telling them to get a hurry on).

This way traffic isn't stalled waiting for an already empty pedestrian crossing to finish.

Without having heard anything differently, I would think the flashing yellow would mean "you were warned by the yellow arrow, this one means it really is going to change. Seriously, it's going to change now."

What is wrong with the way most lights do it now with the green arrow signifying you had the right-of-way, and the green dot meaning you can go when it's clear. I would like to know why more intersections are not equipped with the latter, as the ones that do have them seem to have tremendously less traffic problems.

At least it's not as bad as the roundabout they put in on Highway 13 down south of Prior Lake.

What is wrong with the way most lights do it now with the green arrow signifying you had the right-of-way, and the green dot meaning you can go when it's clear. I would like to know why more intersections are not equipped with the latter, as the ones that do have them seem to have tremendously less traffic problems.

Right- I mentioned that too. I think the problem comes in your larger intersections (where you'd encounter the sign pictured above)...where the solid green would not work (since in certain large intersections, you can't go straight...you can *only* go left)

I don't know, I've been thinking about this one, and it doesn't make sense to me that they would choose a yellow arrow and just make it flash. It seems like either assigning another color to the new arrow, or using some other method to distinguish it is necessary. I really think the flashing yellow arrow is going to make people act the same as the steady yellow arrow does now (slam on the gas, because it's going to change soon.) It's odd because since it's not intuitive, the flashing arrow still needs the same sign that the green dot does, so there doesn't seem to be much of a difference.

Incidentally, do you know how it cycles? Does it go green arrow, yellow arrow, and then either red arrow or flashing yellow?

A great idea, but 138 years too late.

My prediction: This will go the way of the Dvorak keyboard and Swatch internet time. A new "standard" that may be superior, but is too late, and will never catch on.

Usability principle: satisficing. The design we have now works well enough, and whatever small improvements could be made on paper, the overall result is negative because it erodes an established standard.

puck writes:

Stu Pedasso, I think you missed a small detail in the story. The "yield on yellow arrow" sign replaced a "right turn on green arrow only" sign, NOT a "left turn yield on solid green" sign. So before the flashing yellow, they had to wait for the light to cycle all the way back around to a green arrow before they could turn. Some intersections go from green arrow to solid green, and left turns yield on the solid green. But some, like this one apparently, go from green arrow to red arrow, and you have to wait until the next green arrow.

I would have thought an advantage to this approach over the solid green approach is that they can keep the existing green/yellow/red arrow only signals, so they wouldn't have to install new signals, but from looking at the pictures it looks like they put in new signals to do this...so I'm not sure why they have to do this instead of just doing the old "yield on solid green" thing.

Anonymous writes:

There is great momentum towards this signal becoming a national standard. Research is currently being conducted at a national level to evaluate the crash data at over 100 intersection around the country with this signal. The current research suggests that the advantages of the flashing yellow arrow include:

*More capacity (and less congestion) at intersections that previously only had the green arrow.

*Improved safety as the fail-critical situation with a yellow is likely to be drivers waiting when they can go, rather than what happens with the green; when drivers fail they go (its green, you go, naturally) and then get t-boned by an oncoming car.

*Improved consistency throughout the US. Currently many states use different indications, which confuse out-of-state drivers. Driver familiarity impacts safety significantly.

To learn more about the current research conducted by your great Federal agencies do a google search for "flashing yellow arrow". The Digiwest site hosts research documents and the University of Wisconsin "Tops" labs has more recent research and explanations.

Troubleshooter writes:

There is one BIG difference between the flashing yellow arrow and the circular green. They can show the flashing yellow arrow when the straight-ahead signal is red. The circular green can't be displayed at that time. There are several advantages:

- It eliminates the yellow trap hazard. Google yellow trap to learn more.

- It lets the flashing yellow arrow be shown after the green arrow ends, but before the circular green shows. This gives more turning time.

- It allows the permissive turn to be used with lagging left turns (the green arrow is after the opposing circular green).

- Mixed lead and lag signals at the same intersection allow better signal progression (lights turn green as you come to them).

- The signal can be changed between left turn modes by a time clock or computer control:

- exclusively protected (green arrow, no flashing yellow arrow)

- protected-permissive (green arrow and flashing yellow arrow)

- protected-permissive stop (green arrow and flashing red arrow)

- exclusively permissive (flashing yellow arrow, no green arrow)

- exclusively permissive stop (flashing red arrow, no green arrow)

- prohibited turn (red arrow - wait for train to pass)