Has the flashing yellow left turn signal made it to your state?

[Scott5114]

Or use a red straight-ahead arrow along with a flashing yellow left arrow, thereby clearly defining each movement.

now that sounds like one hell of a retrofit.  straight-ahead arrows are pretty uncommon in the US, especially red ones.

Apparently straight-ahead green arrows are standard on MoDOT signals. But the reds are balls.

(Not sure if this applies to all of MoDOT or just the Southwest district)

[route56]

So I missed something simple. Why is the solid green ball bad and the flashing yellow arrow good? Were there a spate of accidents caused by people misinterpreting a green light or something? People are suggesting a ton of ideas that all have the same effect of a solid green ball that drivers are very familiar with. Unless there are reliable, objective studies stating otherwise, I think changing something as fundamental as a traffic light is both dangerous and a waste of money.

I think the potential confusion you're wondering about is the use of so-called "Dallas Phasing," where left-turning traffic opposite a protective left is given a permissive left. Using a circular green to indicate a permissive left under this circumstance would be a problem, as straight-through traffic could look at the left-turn signal instead of their own, see the circular green, and T-bone into someone that had a protected left.

As for the idea that people do not understand the meaning of the flashing arrow. I am not able to cite chapter and verse right now, but I'd be willing to bet that there are objective and reliable studies indicating that the flashing yellow arrow is fairly intuitive to understand - otherwise, they would not have been included in the 2009 MUTCD.

Which brings me back to this....

Here is a situation where the flashing yellow arrow could be very helpful-but could it be used here?
This is Dallas Dr/Bell Av @ Eagle Dr in Denton Tx.

Current setup

I just realized, as I was composing the response above, that, in fact, the use of the flashing yellow arrow would be mandatory if permissive left turns were allowed. The 2009 MUTCD only allows the used of the 5-aspect signal on signal heads that are shared between a turn lane and a travel lane.

[mukade]

As for the idea that people do not understand the meaning of the flashing arrow. I am not able to cite chapter and verse right now, but I'd be willing to bet that there are objective and reliable studies indicating that the flashing yellow arrow is fairly intuitive to understand - otherwise, they would not have been included in the 2009 MUTCD.

Like Clearview. An amazing leap in safety standards.

How many people here who are pretty knowledgeable said they have been momentarily confused at FYA signals? I know it is anecdotal. Nonetheless a green ball is universal - even outside the US, and I never heard of any issue with it.

Didn't the FYA start in Michigan as a way to replace their FRA signals?

[roadfro]

If drivers think a green ball means "I can do whatever I want even if I'm making a left turn and the other direction has a green ball", then the area probably has far too many protected lefts.  Fully protected lefts should be outlawed except if an engineering study proves that there is too much traffic for the typical permissive left or doghouse type left.

That'd be a whole lot of engineering studies to perform. Generally speaking, engineers would be designing the intersection and signalization based on existing and projected future traffic volumes and install protected lefts based on those volumes. I think most well-versed traffic/signal engineers would tell you that they would recommend and install the least restrictive left turn control type wherever possible (and where not in conflict with agency guidelines), because they'd rather achieve better timing/progression--adding protected turn modes increases cycle length and loss time, and affects overall progression bandwidth.

In areas with high traffic volumes, however, protected lefts are absolutely necessary in order to decrease delay for turning traffic--this is simply because there is too much opposing through traffic to clear queues using permissive left turns alone.

There is also the fact that a 5-section display commonly shows both a circular red and a green arrow, when allowing leading protected left turns. Seeing red and green in the same signal face simultaneously sends mixed messages to drivers, and some do not know the proper course of action. A driver *does* need to know how to interpret this display, depending on their intended direction of travel--the number of signal heads or travel lanes doesn't really have anything to do with it.

In addition, a doghouse cannot show a red ball and a permissive left turn. The "solution" (use a separate doghouse over the left turn lane) is confusing at best, since would have to show a green ball when straight traffic has a red.

Why would such a phase exist in the first place?
[/quote]

This is an application of Dallas Phasing, which allows a permitted left turn when adjacent through traffic is red due to an opposing protected left turn--the approach was developed to allow lead-lag protected left turns but still use PPLT displays and permissive modes for additional capacity. Under Dallas Phasing, the doghouse cannot show a red ball (for through traffic) and permissive left turn (green ball for turning traffic) without modification--a separate signal head for the left turn lane is required, along with additional controller programming and louvers/shielding left turn circular indications from the through traffic. The FYA more effectively implements Dallas Phasing schemes because conflicting ball indications are no longer present.

[roadfro]

couldn't there be a red ball and a flashing yellow left arrow in the same doghouse?  or am I misinterpreting what the flashing yellow arrow means?

Not that you're misinterpreting the meaning of the flashing yellow arrow, but more that it brings up the contradictory indications being shown at the same time in the same signal head. (Similar to having the green arrow and red ball on simultaneously.)

Or use a red straight-ahead arrow along with a flashing yellow left arrow, thereby clearly defining each movement.

now that sounds like one hell of a retrofit.  straight-ahead arrows are pretty uncommon in the US, especially red ones.

The MUTCD specifically prohibits straight-ahead red arrows, which is why those are uncommon.

[roadfro]

As for the idea that people do not understand the meaning of the flashing arrow. I am not able to cite chapter and verse right now, but I'd be willing to bet that there are objective and reliable studies indicating that the flashing yellow arrow is fairly intuitive to understand - otherwise, they would not have been included in the 2009 MUTCD.

What led FHWA to adopt the FYA into the MUTCD was the results of a major NCHRP study (and possibly others) which surveyed drivers through a driving simulation. They exposed drivers to every type of protected/permitted display (without explanation or instructional signage) in use at the time in the US. Through these tests, the FYA display was the most understood by all participants--it also produced the best fail-safe response.

Didn't the FYA start in Michigan as a way to replace their FRA signals?

The first implementations of FYA were actually in Reno, NV in the mid-late 1990s, but were removed by 2001 due to a change in head city engineers and philosophy on traffic control.

The research and studies leading to FYA adoption were taken on in part because there were so many PPLT signal variations out there...I think there was something like 9-10 variants in the U.S. at the time that were not MUTCD-standard 5-aspect displays.

[agentsteel53]

Not that you're misinterpreting the meaning of the flashing yellow arrow, but more that it brings up the contradictory indications being shown at the same time in the same signal head. (Similar to having the green arrow and red ball on simultaneously.)

...

The MUTCD specifically prohibits straight-ahead red arrows, which is why those are uncommon.

it seems like having a red straight arrow with a non-red turn arrow would alleviate precisely this confusion of a doghouse showing multiple colors.

[vdeane]

This is an application of Dallas Phasing, which allows a permitted left turn when adjacent through traffic is red due to an opposing protected left turn--the approach was developed to allow lead-lag protected left turns but still use PPLT displays and permissive modes for additional capacity. Under Dallas Phasing, the doghouse cannot show a red ball (for through traffic) and permissive left turn (green ball for turning traffic) without modification--a separate signal head for the left turn lane is required, along with additional controller programming and louvers/shielding left turn circular indications from the through traffic. The FYA more effectively implements Dallas Phasing schemes because conflicting ball indications are no longer present.

That would be why I don't understand it.  I've never seen a signal that used Dallas Phasing in my entire life.  In upstate NY, we just use unprotected lefts in typical situation, fully protected lefts on divided highways (only exceptions I can think of is US 11 at NY 345 and NY 342 at US 11 (this will probably disappear soon); both of these are in region 7), and doghouses if a protected left phase is warranted.

[agentsteel53]

I've seen so many bizarre timing variants that Dallas Phasing doesn't faze me at all.

"oh, straight traffic is red, and the arrow is green.  yeap."

[roadfro]

it seems like having a red straight arrow with a non-red turn arrow would alleviate precisely this confusion of a doghouse showing multiple colors.

If a straight red were allowed, a green and yellow turn arrow shouldn't be terminated with a straight red arrow in that manner though...

[agentsteel53]

If a straight red were allowed, a green and yellow turn arrow shouldn't be terminated with a straight red arrow in that manner though...

why not?

the only drawback I can think of is minor initial confusion during the changeover phase, but it should be comparable to confusion regarding a doghouse with a red ball and a left arrow (either green or yellow). 

[vdeane]

I've seen so many bizarre timing variants that Dallas Phasing doesn't faze me at all.

"oh, straight traffic is red, and the arrow is green.  yeap."

That's not what gets me with this... it's that in NY, a straight red but green left is always protected, not permissive.

[agentsteel53]

That's not what gets me with this... it's that in NY, a straight red but green left is always protected, not permissive.

I believe red ball with flashing yellow arrow would indicate the permissive situation you desire.

[roadfro]

If a straight red were allowed, a green and yellow turn arrow shouldn't be terminated with a straight red arrow in that manner though...

why not?

the only drawback I can think of is minor initial confusion during the changeover phase, but it should be comparable to confusion regarding a doghouse with a red ball and a left arrow (either green or yellow).

In the doghouse display, the red section applies to both the protected left turn indications and the through movement indications (or the permissive left indications, in now-defunct Dallas Phasing applications). Essentially, the doghouse acts as two separate signal heads combined into one, with the red shared.

If you separated the two movements into separate signal heads, would it make sense to have green left arrow, yellow left arrow and red straight arrow in one head? Similarly, the other head would have green ball, yellow ball and red straight arrow.

The typical operation of the doghouse makes a bit more sense when imagined as two separate signal heads. The permissive side is a standard signal. The protected side is green left arrow, yellow left arrow, red ball--which by itself the MUTCD considered an acceptable method of displaying protected left turns before red arrows became common.

[Mdcastle]

I saw a signal in VA that was a three segment display with FYA, Yellow Arrow, Red Arrow. Is this MUTCD compliant for a permissive only FYA installation? I can see why it would be used as you can just change out the LEDs without changing out the entire face, but on the other hand it seems to me a 4-head would be better (even if they don't bother installing a functional module in the bottom section) since drivers are used to seeing a green segment on the bottom.

[US71]

I saw a signal in VA that was a three segment display with FYA, Yellow Arrow, Red Arrow. Is this MUTCD compliant for a permissive only FYA installation? I can see why it would be used as you can just change out the LEDs without changing out the entire face, but on the other hand it seems to me a 4-head would be better (even if they don't bother installing a functional module in the bottom section) since drivers are used to seeing a green segment on the bottom.

Must be: I've seen 2 in Arkansas. Oncoming has a protected left & steady green for thru traffic, but the other direction is FYA only.

[Takumi]

That's the first one like that I've heard of here. The ones I've seen all have four segments, as a post at the beginning of this thread shows.

[SignBridge]

Mdcastle, that signal you saw in Va. is the accepted arrangement in the MUTCD, for a separate left-turn signal face mounted over or in-front-of a separate left-turn lane, with permissive turns only. The F-Y-A in the bottom position replaces the green-ball.

[Revive 755]

As for the idea that people do not understand the meaning of the flashing arrow. I am not able to cite chapter and verse right now, but I'd be willing to bet that there are objective and reliable studies indicating that the flashing yellow arrow is fairly intuitive to understand - otherwise, they would not have been included in the 2009 MUTCD.

Like Clearview. An amazing leap in safety standards.

And almost as wonderful as the 2009 MUTCD screwing up street blade signs and optional lane guide signing

couldn't there be a red ball and a flashing yellow left arrow in the same doghouse?  or am I misinterpreting what the flashing yellow arrow means?

Not that you're misinterpreting the meaning of the flashing yellow arrow, but more that it brings up the contradictory indications being shown at the same time in the same signal head. (Similar to having the green arrow and red ball on simultaneously.)

The MUTCD specifically prohibits straight-ahead red arrows, which is why those are uncommon.

Possible another flaw in the MUTCD.  I could see prohibiting straight red or yellow arrows if the indications are the dimmer incandescent variety, but the newer LED indications aren't hard at all to spot from a distance, and should be allowed as an option.  There are a couple setups in Kenosha, WI, that would benefit from straight yellow and red arrows in one of the heads:

http://maps.google.com/maps?q=kenosha,+wi&hl=en&ll=42.566871,-87.887496&spn=0.001677,0.004128&sll=42.10561,-88.076363&sspn=0.215233,0.528374&hnear=Kenosha,+Wisconsin&t=m&z=19&layer=c&cbll=42.566871,-87.887496&panoid=Uw1uj2kur2aT-Qsx5Bb_3g&cbp=12,232.98,,0,3.57

[vdeane]

I saw a signal in VA that was a three segment display with FYA, Yellow Arrow, Red Arrow. Is this MUTCD compliant for a permissive only FYA installation?

I think so, though I'm wondering what the point is of having a separate left turn signal here at all.

And almost as wonderful as the 2009 MUTCD screwing up street blade signs and optional lane guide signing

I can't agree about the street blade signs.  Many places install street blades that are unreadable even during the day.  Forcing these places to change to a standardized sign can only be an improvement.

[roadfro]

The MUTCD specifically prohibits straight-ahead red arrows, which is why those are uncommon.

Possible another flaw in the MUTCD.  I could see prohibiting straight red or yellow arrows if the indications are the dimmer incandescent variety, but the newer LED indications aren't hard at all to spot from a distance, and should be allowed as an option.  There are a couple setups in Kenosha, WI, that would benefit from straight yellow and red arrows in one of the heads:

http://maps.google.com/maps?q=kenosha,+wi&hl=en&ll=42.566871,-87.887496&spn=0.001677,0.004128&sll=42.10561,-88.076363&sspn=0.215233,0.528374&hnear=Kenosha,+Wisconsin&t=m&z=19&layer=c&cbll=42.566871,-87.887496&panoid=Uw1uj2kur2aT-Qsx5Bb_3g&cbp=12,232.98,,0,3.57

The linked setup would better benefit from physical separation of the left turn and through signal heads, instead of changing the indications.

[SignBridge]

Deanej, I agree with you about street blade signs. I have driven thru some very exclusive villages that had very decorative, but almost unreadable steet signs. Definitely time for standardization, though I bet those villages won't change.

Re: the separate left-turn signal, maybe the particular intersection had a history of left-turn accidents, so they installed the FYA for greater clarity and compliance. I agree that the public should understand that you need to yield to thru traffic on a green-ball, but I'm in favor of FYA if it will keep some idiot from turning left in front of me and ruining my life.

And 755, I agree with you about the optional-lane signing. The FWHA created a problem where there wasn't one (in my opinion)

[PurdueBill]

None around here yet but maybe we could use them.  Twice today, yes twice, I saw people who pulled up to the line in the left turn lane too late to trigger an arrow on a doghouse signal decide to just go on red anyway when enough of a break the other way (with green circle and left arrow for oncoming) opened up.  Perhaps sensible if there were a FYA facing our way, but definitely not legal without one. 

[Central Avenue]

I think so, though I'm wondering what the point is of having a separate left turn signal here at all.

The only thing I could think of is some kind of situation where it would be desirable to control the permissive-only left separate from the through movement. So you could have the left signal red while the through is green or the left flashing yellow while the through is red.

But I'm not sure whether that would ever be useful...

[mjb2002]

As for the idea that people do not understand the meaning of the flashing arrow. I am not able to cite chapter and verse right now, but I'd be willing to bet that there are objective and reliable studies indicating that the flashing yellow arrow is fairly intuitive to understand - otherwise, they would not have been included in the 2009 MUTCD.

Like Clearview. An amazing leap in safety standards.

And almost as wonderful as the 2009 MUTCD screwing up street blade signs and optional lane guide signing

Actually, the 2009 MUTCD made the correct call concerning Street Name signs, something that should have been done in 1988 - when the "sign every street initiative was included". However, it DID screw up Destination signs, badly.

couldn't there be a red ball and a flashing yellow left arrow in the same doghouse?  or am I misinterpreting what the flashing yellow arrow means?

Not that you're misinterpreting the meaning of the flashing yellow arrow, but more that it brings up the contradictory indications being shown at the same time in the same signal head. (Similar to having the green arrow and red ball on simultaneously.)

The MUTCD specifically prohibits straight-ahead red arrows, which is why those are uncommon.

Possible another flaw in the MUTCD.  I could see prohibiting straight red or yellow arrows if the indications are the dimmer incandescent variety, but the newer LED indications aren't hard at all to spot from a distance, and should be allowed as an option.  There are a couple setups in Kenosha, WI, that would benefit from straight yellow and red arrows in one of the heads:

http://maps.google.com/maps?q=kenosha,+wi&hl=en&ll=42.566871,-87.887496&spn=0.001677,0.004128&sll=42.10561,-88.076363&sspn=0.215233,0.528374&hnear=Kenosha,+Wisconsin&t=m&z=19&layer=c&cbll=42.566871,-87.887496&panoid=Uw1uj2kur2aT-Qsx5Bb_3g&cbp=12,232.98,,0,3.57