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

[JKRhodes]

In this application, the right turn FYA is telling drivers that they have an ALMOST free right turn - the only traffic they need to yield to are u-turners.

The only problem I see is that while FYA always seems to indicate a yield condition, it doesn't always indicate yielding to the same issue.  In some cases, it's to yield to pedestrians on your right.  In some cases its to yield to u-turners, and in other cases its to yield to opposing traffic or even side street traffic.  One key basis of safety is uniformity of meaning, and I don't beleive that is accomplished here.

When I approach a RTOR, I sometimes ask myself, who has the green.  Obviously, my reaction is different depending upon whether cross traffic or opposing protected left turns have the right of way.  I guess people have to ask themselves that same question as they approach a FYA.

Yeah, it's the same situation to process as if you were making a RTOR. Is the cross traffic going? Is there U-turn traffic happening? Are there pedestrians? You must yield to traffic lawfully in the intersection.

But I can understand the concern. There's many a case where a right turn on red is not recognizing the right of way of a U-turn legally proceeding on green arrow, so a FYA for the right could exacerbate some of that problem...

There may actually be an advantage to using the flashing yellow right arrow. When approaching an intersection where the cross-street has a signalized U-turn, an all-red display for the approach road may lead drivers to look in the wrong direction when they make their right turn on red. For example: approaching the cross-street, seeing traffic from the left is stopped, and then proceeding. Not realizing that they have to yield to those making U-turns. This is perfectly logical because at most intersections, when making a right-on-red, the conflicting traffic is largely from the left (although also a green arrow for drivers turning left from the opposing road, but this is a shorter phase). Thus drivers primarily look left to determine if it's clear.

With a flashing yellow arrow facing to the right, it's clearer to drivers approaching the intersection that they need to yield to drivers making U-turns. A supplemental "yield to U-turns on flashing yellow arrow" should be posted to actually indicate the specific meaning (since it's not actually clear on its own), but it would be a signal unique to that specific phase. Compare this to an approach where all signals are red, which really just tells drivers that "some other approach has full priority right now ... figure it out if you want to turn on red". Drivers do figure it out, by and large, but often ignore those making U-turns.

As a side-note: "U-turn yield to right turn" is insane and I cannot believe it's as common as it is. I cannot think a maneuver more awkward than that. And I get to turn left on red from a two-way to a one way street here in WA!

I like your thinking here. That would be a good application.

And I agree, "U-turn yield to right turn" is ridiculous, especially when the left/U turn traffic is on a green arrow. Never seen it in real life (only in mentions on this forum) and hope I never do.

https://goo.gl/maps/hBEGzFyxxMQic92P8

This intersection in Tucson had "U-turn yield to right turn" for several years following its reconstruction around 2002. Unfortunately I don't have any pictures of the old setup, and it was well before the advent of Google Street View.

It's technically  located inside an unincorporated Pima County island. Pima County's road design guidelines didn't allow for the right turn FYA that Tucson uses at its eastside intersections. I believe ADOT had some input in the design process for this intersection as well.

The signage has changed somewhat regularly over the years. In its current state, U-turns and RTOR are both prohibited. 2013 street view shows an LED illuminated no-right-turn sign, and a Pima county sheriff's deputy posted on the corner in a Crown Vic doing traffic enforcement.

[Amtrakprod]

I uploaded a YT video showing the light: https://youtu.be/qz1hdXpjB-c


iPhone

I'm really confused. Is that approach split-phased, with one approach allowing left turns on FYA when the other direction has a green?

Yes. The side street here remains a split phase with one side allowing yielding for left turns when the other side is green. This was the exact phasing at the old signal (minus the left turn being able to yield due to the lack of any left turn signal). This is only temporary as the signal is soon to be timed with the new bike path signal. That will make this signal the first FYA signal in MA to use red arrows.


iPhone

[jakeroot]

I uploaded a YT video showing the light: https://youtu.be/qz1hdXpjB-c

I'm really confused. Is that approach split-phased, with one approach allowing left turns on FYA when the other direction has a green?

Yes. The side street here remains a split phase with one side allowing yielding for left turns when the other side is green. This was the exact phasing at the old signal (minus the left turn being able to yield due to the lack of any left turn signal). This is only temporary as the signal is soon to be timed with the new bike path signal. That will make this signal the first FYA signal in MA to use red arrows.

So the first to use partially-protected-only phasing? Or the first to actually use a red arrow? Since all the FYA signals around here utilize a red arrow on the top. Apart from a few in a couple select locations.

I've been waiting for someone to implement an FYA at a split-phased intersection. I've only seen it done once, at this intersection, and it's only barely related to the setup in your video.

[Amtrakprod]

I uploaded a YT video showing the light: https://youtu.be/qz1hdXpjB-c

I'm really confused. Is that approach split-phased, with one approach allowing left turns on FYA when the other direction has a green?

Yes. The side street here remains a split phase with one side allowing yielding for left turns when the other side is green. This was the exact phasing at the old signal (minus the left turn being able to yield due to the lack of any left turn signal). This is only temporary as the signal is soon to be timed with the new bike path signal. That will make this signal the first FYA signal in MA to use red arrows.

So the first to use partially-protected-only phasing? Or the first to actually use a red arrow? Since all the FYA signals around here utilize a red arrow on the top. Apart from a few in a couple select locations.

I've been waiting for someone to implement an FYA at a split-phased intersection. I've only seen it done once, at this intersection, and it's only barely related to the setup in your video.

1. The first to use partially protected only phasing. Most lights in MA utilize a red arrow but no protected phasing at all.

[UCFKnights]

I like your thinking here [with regards to right turn yield to U-turn on FYA]. That would be a good application.

Thanks! I've seen the right-facing FYA in-action in Tucson, and I thought it was pretty smart and a good halfway between the traditional "yield on red" and the awful "U-turn yield to right turn".

And I agree, "U-turn yield to right turn" is ridiculous, especially when the left/U turn traffic is on a green arrow. Never seen it in real life (only in mentions on this forum) and hope I never do.

I guess some states take the arrow direction quite literally. Here, a green arrow facing left would allow you to depart an intersection in any direction left-of-center, including U-turns. To then say that the green arrow doesn't include ROW to make a U-turn seems rather strange when I've been taught from day one to treat green arrows as the holy grail of protected signals. Apparently not in every state!

I would think that, if U-turns were even remotely common, the whole "yield to right turners" action would create significant backups in the left turn lane. If that's the case, why even permit U-turns to begin with? I don't get it, man. I don't get it.

Florida is another U turn yield to right turn state. In practice, it doesn't seem to ever cause any sort of backups in the left turn lane. One big aspect of that is there is usually plenty of room for one car to queue while U turning without blocking the left turns. Also usually right turn traffic is light enough to allow easy, quick yielding, as the right turn green arrow was preceded by a green ball, so there is usually no queue you're waiting for. If there's ever heavy left turn on right turn traffic, they seem pretty quick to stick up a no U turn sign since U turns always take a little longer then a basic left turn.

[STLmapboy]

OK Kentucky this is not the place for a permissive-only FYA.

[jakeroot]

1. The first to use partially protected only phasing. Most lights in MA utilize a red arrow but no protected phasing at all.

Very nice. It's quite common in WA now.

Florida is another U turn yield to right turn state. In practice, it doesn't seem to ever cause any sort of backups in the left turn lane. One big aspect of that is there is usually plenty of room for one car to queue while U turning without blocking the left turns. Also usually right turn traffic is light enough to allow easy, quick yielding, as the right turn green arrow was preceded by a green ball, so there is usually no queue you're waiting for. If there's ever heavy left turn on right turn traffic, they seem pretty quick to stick up a no U turn sign since U turns always take a little longer then a basic left turn.

Most of the time I've seen the sign, U-turns are very light. This is in stark contrast to signed U-turns in my area (usually along corridors with medians), where there is an exorbitant number of people doing U-turns so often that they could not possibly ban the maneuver, nor install a "yield to right turners" sign without seeing serious issues with left-turn lane congestion (with too many people waiting to U-turn).

OK Kentucky this is not the place for a permissive-only FYA.

I'm not sure I see an issue. Only a couple lanes; I don't think there's too much oncoming traffic; and there's plenty of room to stop past the stop line to allow someone to finish a turn on red, if no gap develops.

[roadfro]

OK Kentucky this is not the place for a permissive-only FYA.

I'm not sure I see an issue. Only a couple lanes; I don't think there's too much oncoming traffic; and there's plenty of room to stop past the stop line to allow someone to finish a turn on red, if no gap develops.

I agree with Jake, not seeing a big deal here. Yeah, there's three opposing lanes, but that is not inherently dangerous. The 'almost' positive offset left turn lane aids in visibility and should make the permitted left easier here.

[jakeroot]

OK Kentucky this is not the place for a permissive-only FYA.

I'm not sure I see an issue. Only a couple lanes; I don't think there's too much oncoming traffic; and there's plenty of room to stop past the stop line to allow someone to finish a turn on red, if no gap develops.

I agree with Jake, not seeing a big deal here. Yeah, there's three opposing lanes, but that is not inherently dangerous. The 'almost' positive offset left turn lane aids in visibility and should make the permitted left easier here.

Definitely! And I think with the double left turn being pushed back a bit from the intersection, that also helps improve visibility for the permissive left.

As far as permissive left turns go, this is a very well designed example.

[fwydriver405]

I uploaded a YT video showing the light: https://youtu.be/qz1hdXpjB-c

I'm really confused. Is that approach split-phased, with one approach allowing left turns on FYA when the other direction has a green?

Yes. The side street here remains a split phase with one side allowing yielding for left turns when the other side is green. This was the exact phasing at the old signal (minus the left turn being able to yield due to the lack of any left turn signal). This is only temporary as the signal is soon to be timed with the new bike path signal. That will make this signal the first FYA signal in MA to use red arrows.

So the first to use partially-protected-only phasing? Or the first to actually use a red arrow? Since all the FYA signals around here utilize a red arrow on the top. Apart from a few in a couple select locations.

I've been waiting for someone to implement an FYA at a split-phased intersection. I've only seen it done once, at this intersection, and it's only barely related to the setup in your video.

1. The first to use partially protected only phasing. Most lights in MA utilize a red arrow but no protected phasing at all.

Yesterday, I noticed a strange issue with this light as I had to pass thru it when I went to go see a friend around that area. Take note that all approaches at this intersection are single lane.

I needed to make a left turn onto Lake... however the FYA showed a red arrow. Thinking that this was strange and maybe I didn't arrive on time... I waited another cycle. Same thing on the second and third cycles.

At the 4th cycle, I just ended up going straight, then using Orvis Rd to make a U-turn to make that intended turn onto Lake.

Is it possible that this signal isn't fully programmed correctly? I thought FYA's were not allowed to be used on single lane approches...

[Amtrakprod]

I uploaded a YT video showing the light: https://youtu.be/qz1hdXpjB-c

I'm really confused. Is that approach split-phased, with one approach allowing left turns on FYA when the other direction has a green?

Yes. The side street here remains a split phase with one side allowing yielding for left turns when the other side is green. This was the exact phasing at the old signal (minus the left turn being able to yield due to the lack of any left turn signal). This is only temporary as the signal is soon to be timed with the new bike path signal. That will make this signal the first FYA signal in MA to use red arrows.

So the first to use partially-protected-only phasing? Or the first to actually use a red arrow? Since all the FYA signals around here utilize a red arrow on the top. Apart from a few in a couple select locations.

I've been waiting for someone to implement an FYA at a split-phased intersection. I've only seen it done once, at this intersection, and it's only barely related to the setup in your video.

1. The first to use partially protected only phasing. Most lights in MA utilize a red arrow but no protected phasing at all.

Yesterday, I noticed a strange issue with this light as I had to pass thru it when I went to go see a friend around that area. Take note that all approaches at this intersection are single lane.

I needed to make a left turn onto Lake... however the FYA showed a red arrow. Thinking that this was strange and maybe I didn't arrive on time... I waited another cycle. Same thing on the second and third cycles.

At the 4th cycle, I just ended up going straight, then using Orvis Rd to make a U-turn to make that intended turn onto Lake.

Is it possible that this signal isn't fully programmed correctly? I thought FYA's were not allowed to be used on single lane approches...

What in the heck? I knew it would be a TOD signal but this is bad.

[Amtrakprod]

I uploaded a YT video showing the light: https://youtu.be/qz1hdXpjB-c

I'm really confused. Is that approach split-phased, with one approach allowing left turns on FYA when the other direction has a green?

Yes. The side street here remains a split phase with one side allowing yielding for left turns when the other side is green. This was the exact phasing at the old signal (minus the left turn being able to yield due to the lack of any left turn signal). This is only temporary as the signal is soon to be timed with the new bike path signal. That will make this signal the first FYA signal in MA to use red arrows.

So the first to use partially-protected-only phasing? Or the first to actually use a red arrow? Since all the FYA signals around here utilize a red arrow on the top. Apart from a few in a couple select locations.

I've been waiting for someone to implement an FYA at a split-phased intersection. I've only seen it done once, at this intersection, and it's only barely related to the setup in your video.

1. The first to use partially protected only phasing. Most lights in MA utilize a red arrow but no protected phasing at all.

Yesterday, I noticed a strange issue with this light as I had to pass thru it when I went to go see a friend around that area. Take note that all approaches at this intersection are single lane.

I needed to make a left turn onto Lake... however the FYA showed a red arrow. Thinking that this was strange and maybe I didn't arrive on time... I waited another cycle. Same thing on the second and third cycles.

At the 4th cycle, I just ended up going straight, then using Orvis Rd to make a U-turn to make that intended turn onto Lake.

Is it possible that this signal isn't fully programmed correctly? I thought FYA's were not allowed to be used on single lane approches...

Here's a video I took of it on 10/1.
https://youtu.be/y_FCVt06kfQ

[jakeroot]

That is a very unusual situation. I don't really know what to make of it. fwydriver405's video definitely shows it malfunctioning. I personally would have just turned left on the second cycle; your dashcam clearly shows it as broken, and this could be used as evidence if for some reason you got a ticket. I've blown through numerous red arrows, even when they were functioning correctly, as I was just impatient. I wouldn't think twice about ignoring that one.

If an FYA signal is going to be used for an option-lane approach (sort of verboten but there is precedence), it certainly should not use any protected-only phasing (be it TOD or for pedestrian protection). Green arrows should be used at the beginning, to avoid yellow trap for the opposing left turn (assuming the alternative was a lagging green arrow, and the other approach does not have an FYA signal), but the phase should not include the interim red arrow (instead: green arrow > solid yellow arrow > flashing yellow arrow > solid yellow arrow > all red). This would avoid any sort of 'red arrow + green ball' situation with an option lane, which should really be the goal here.

For the approach in the video, I'd recommend the 5-section FYA signal, with combined FYA and green ball displays. This would allow the FYA to be used even when the main display was red, but no red arrow would be possible, avoiding any issues like those seen in the video.

[fwydriver405]

Amtrakprod, when you said the signal runs on TOD phasing, did you say it was TOD phasing because it changes between permissive only and protected/permissive? I am only making that hypothesis based on the signal plans.

---

As for that signal phasing, I showed the video to a signal tech in my area, and he believes either dual entry isn't enabled for my approch, or the detector isn't calling the correct phases:

It is likely it is phased correctly, however dual entry is not enabled for the approach you were on and the opposing. As such the opposing light had a red display and the FYA overlap is tied to the opposing green indication.

Otherwise, based on the plans there should be a Phase 7 and it doesn't look like the detector is calling up that phase, else you would get the green (or flashing yellow) arrow.

I have a second video somewhere showing that the FYA does flash yellow when that approach gets a call, although either the driver on that same approch overshot the stop line, and/or the left turning driver from WB Lake to NB Brooks turned into the oncoming lane briefly, triggering the oncoming Brook St approch to allow the FYA to flash.

The controller isn't consistent on what phasing it wants to initate... sometimes in similar scenarios it goes to permissive only for both directions, sometimes single leading left then permissive, or the red arrow situation mentioned above.

[Amtrakprod]

Amtrakprod, when you said the signal runs on TOD phasing, did you say it was TOD phasing because it changes between permissive only and protected/permissive? I am only making that hypothesis based on the signal plans.

---

As for that signal phasing, I showed the video to a signal tech in my area, and he believes either dual entry isn't enabled for my approch, or the detector isn't calling the correct phases:

It is likely it is phased correctly, however dual entry is not enabled for the approach you were on and the opposing. As such the opposing light had a red display and the FYA overlap is tied to the opposing green indication.

Otherwise, based on the plans there should be a Phase 7 and it doesn't look like the detector is calling up that phase, else you would get the green (or flashing yellow) arrow.

I have a second video somewhere showing that the FYA does flash yellow when that approach gets a call, although either the driver on that same approch overshot the stop line, and/or the left turning driver from WB Lake to NB Brooks turned into the oncoming lane briefly, triggering the oncoming Brook St approch to allow the FYA to flash.

The controller isn't consistent on what phasing it wants to initate... sometimes in similar scenarios it goes to permissive only for both directions, sometimes single leading left then permissive, or the red arrow situation mentioned above.

Wait what? Can I see the other video? Something weird is going on there. The bike way signal also hasn't been activated, once that is (hopefully soon) it will be better


iPhone

[Amtrakprod]

https://youtu.be/n1UobIzy7WE


iPhone

[jakeroot]

https://youtu.be/n1UobIzy7WE

This practice is actually quite common at left turn FYA signals in my area. The yellow for the FYA seems to last about a quarter second less than the through traffic. I assume it's an error since it should end simultaneous with through traffic, but it's a common error nonetheless.

[roadfro]

https://youtu.be/n1UobIzy7WE

This practice is actually quite common at left turn FYA signals in my area. The yellow for the FYA seems to last about a quarter second less than the through traffic. I assume it's an error since it should end simultaneous with through traffic, but it's a common error nonetheless.

I see around Reno all the time where the left yellow arrow and the through circular yellow don't terminate together. I thought it was weird when I first saw it, as my frame of reference was the Vegas area where the yellows do tend to terminate simultaneously. It can be weird if you're not used to it, but it's not necessarily an error. And I don't believe there is anything in the MUTCD that mandates the yellows terminate simultaneously.

Many jurisdictions follow the Institute of Traffic Engineers various formulas for signal phasing and indications. The ITE formula for the duration of a yellow clearance interval is a function of the 85th percentile speed (among other factors). I think some agencies use a slower turning speed for left turn movements than the speed limit of adjacent through movements, which may result in the difference in yellow intervals.

[jakeroot]

https://youtu.be/n1UobIzy7WE

This practice is actually quite common at left turn FYA signals in my area. The yellow for the FYA seems to last about a quarter second less than the through traffic. I assume it's an error since it should end simultaneous with through traffic, but it's a common error nonetheless.

I see around Reno all the time where the left yellow arrow and the through circular yellow don't terminate together. I thought it was weird when I first saw it, as my frame of reference was the Vegas area where the yellows do tend to terminate simultaneously. It can be weird if you're not used to it, but it's not necessarily an error. And I don't believe there is anything in the MUTCD that mandates the yellows terminate simultaneously.

Many jurisdictions follow the Institute of Traffic Engineers various formulas for signal phasing and indications. The ITE formula for the duration of a yellow clearance interval is a function of the 85th percentile speed (among other factors). I think some agencies use a slower turning speed for left turn movements than the speed limit of adjacent through movements, which may result in the difference in yellow intervals.

One possible issue may be with programming, and the possibility that most are set so that the solid yellow phase lasts the same time no matter if the solid yellow is after a green arrow (where 85th percentile speeds are relevant) or after a flashing yellow arrow (where the importance is more on 'make sure left turning traffic doesn't turn into oncoming traffic'). It would be appropriate to have a shorter yellow phase after the protected green phase, but not after the flashing yellow arrow phase. In my opinion, since left turn FYA signals are necessarily tied to through traffic, the solid yellow really should be tied to the through signals since, assuming the phase in question is after the permissive phase and when both through traffic and left turning traffic are about to face a red signal, traffic turning left must be certain that it is safe to finish their turn. The chance of an issue arising seems slim (probably is slim), but the potential is there.

[roadfro]

https://youtu.be/n1UobIzy7WE

This practice is actually quite common at left turn FYA signals in my area. The yellow for the FYA seems to last about a quarter second less than the through traffic. I assume it's an error since it should end simultaneous with through traffic, but it's a common error nonetheless.

I see around Reno all the time where the left yellow arrow and the through circular yellow don't terminate together. I thought it was weird when I first saw it, as my frame of reference was the Vegas area where the yellows do tend to terminate simultaneously. It can be weird if you're not used to it, but it's not necessarily an error. And I don't believe there is anything in the MUTCD that mandates the yellows terminate simultaneously.

Many jurisdictions follow the Institute of Traffic Engineers various formulas for signal phasing and indications. The ITE formula for the duration of a yellow clearance interval is a function of the 85th percentile speed (among other factors). I think some agencies use a slower turning speed for left turn movements than the speed limit of adjacent through movements, which may result in the difference in yellow intervals.

One possible issue may be with programming, and the possibility that most are set so that the solid yellow phase lasts the same time no matter if the solid yellow is after a green arrow (where 85th percentile speeds are relevant) or after a flashing yellow arrow (where the importance is more on 'make sure left turning traffic doesn't turn into oncoming traffic'). It would be appropriate to have a shorter yellow phase after the protected green phase, but not after the flashing yellow arrow phase. In my opinion, since left turn FYA signals are necessarily tied to through traffic, the solid yellow really should be tied to the through signals since, assuming the phase in question is after the permissive phase and when both through traffic and left turning traffic are about to face a red signal, traffic turning left must be certain that it is safe to finish their turn. The chance of an issue arising seems slim (probably is slim), but the potential is there.

I can see some of what you're saying here.

The realities of signal controller programming doesn't make a distinction though. There's typically only one setting per phase  for duration of yellow & red clearance intervals, so whether it follows a green or flashing yellow is typically irrelevant.

[jakeroot]

https://youtu.be/n1UobIzy7WE

This practice is actually quite common at left turn FYA signals in my area. The yellow for the FYA seems to last about a quarter second less than the through traffic. I assume it's an error since it should end simultaneous with through traffic, but it's a common error nonetheless.

I see around Reno all the time where the left yellow arrow and the through circular yellow don't terminate together. I thought it was weird when I first saw it, as my frame of reference was the Vegas area where the yellows do tend to terminate simultaneously. It can be weird if you're not used to it, but it's not necessarily an error. And I don't believe there is anything in the MUTCD that mandates the yellows terminate simultaneously.

Many jurisdictions follow the Institute of Traffic Engineers various formulas for signal phasing and indications. The ITE formula for the duration of a yellow clearance interval is a function of the 85th percentile speed (among other factors). I think some agencies use a slower turning speed for left turn movements than the speed limit of adjacent through movements, which may result in the difference in yellow intervals.

One possible issue may be with programming, and the possibility that most are set so that the solid yellow phase lasts the same time no matter if the solid yellow is after a green arrow (where 85th percentile speeds are relevant) or after a flashing yellow arrow (where the importance is more on 'make sure left turning traffic doesn't turn into oncoming traffic'). It would be appropriate to have a shorter yellow phase after the protected green phase, but not after the flashing yellow arrow phase. In my opinion, since left turn FYA signals are necessarily tied to through traffic, the solid yellow really should be tied to the through signals since, assuming the phase in question is after the permissive phase and when both through traffic and left turning traffic are about to face a red signal, traffic turning left must be certain that it is safe to finish their turn. The chance of an issue arising seems slim (probably is slim), but the potential is there.

I can see some of what you're saying here.

The realities of signal controller programming doesn't make a distinction though. There's typically only one setting per phase  for duration of yellow & red clearance intervals, so whether it follows a green or flashing yellow is typically irrelevant.

That's pretty unfortunate, and what I was afraid of.

Based on this, it would seem that the solid yellow phase for the FYA signal should to be identical to the solid yellow phase for the through signal. At the end of the day, I doubt the 85th percentile speeds are different enough that the FYA signal even needs its own unique solid yellow phase length separate from that of the through traffic.

The biggest benefit to me would be at intersections where there are red light cameras. If the left turn FYA signal had a different yellow and red clearance interval, traffic turning left could, theoretically, be issued a ticket for entering on red at the same time as someone going straight, who possibly entered on yellow and therefore did not break the law and would not be issued a ticket. In reality, I suspect intersections with red light cameras are programmed correctly with the left turn FYA signal's solid yellow phase identical to that of the through traffic, but it would be far more desirable for this to be the case at all intersections, and not just those where a driver's wallet is at jeopardy.

[mrsman]

https://youtu.be/n1UobIzy7WE

This practice is actually quite common at left turn FYA signals in my area. The yellow for the FYA seems to last about a quarter second less than the through traffic. I assume it's an error since it should end simultaneous with through traffic, but it's a common error nonetheless.

I see around Reno all the time where the left yellow arrow and the through circular yellow don't terminate together. I thought it was weird when I first saw it, as my frame of reference was the Vegas area where the yellows do tend to terminate simultaneously. It can be weird if you're not used to it, but it's not necessarily an error. And I don't believe there is anything in the MUTCD that mandates the yellows terminate simultaneously.

Many jurisdictions follow the Institute of Traffic Engineers various formulas for signal phasing and indications. The ITE formula for the duration of a yellow clearance interval is a function of the 85th percentile speed (among other factors). I think some agencies use a slower turning speed for left turn movements than the speed limit of adjacent through movements, which may result in the difference in yellow intervals.

One possible issue may be with programming, and the possibility that most are set so that the solid yellow phase lasts the same time no matter if the solid yellow is after a green arrow (where 85th percentile speeds are relevant) or after a flashing yellow arrow (where the importance is more on 'make sure left turning traffic doesn't turn into oncoming traffic'). It would be appropriate to have a shorter yellow phase after the protected green phase, but not after the flashing yellow arrow phase. In my opinion, since left turn FYA signals are necessarily tied to through traffic, the solid yellow really should be tied to the through signals since, assuming the phase in question is after the permissive phase and when both through traffic and left turning traffic are about to face a red signal, traffic turning left must be certain that it is safe to finish their turn. The chance of an issue arising seems slim (probably is slim), but the potential is there.

I can see some of what you're saying here.

The realities of signal controller programming doesn't make a distinction though. There's typically only one setting per phase  for duration of yellow & red clearance intervals, so whether it follows a green or flashing yellow is typically irrelevant.

That's pretty unfortunate, and what I was afraid of.

Based on this, it would seem that the solid yellow phase for the FYA signal should to be identical to the solid yellow phase for the through signal. At the end of the day, I doubt the 85th percentile speeds are different enough that the FYA signal even needs its own unique solid yellow phase length separate from that of the through traffic.

The biggest benefit to me would be at intersections where there are red light cameras. If the left turn FYA signal had a different yellow and red clearance interval, traffic turning left could, theoretically, be issued a ticket for entering on red at the same time as someone going straight, who possibly entered on yellow and therefore did not break the law and would not be issued a ticket. In reality, I suspect intersections with red light cameras are programmed correctly with the left turn FYA signal's solid yellow phase identical to that of the through traffic, but it would be far more desirable for this to be the case at all intersections, and not just those where a driver's wallet is at jeopardy.

Is it true that the 85th percentile speeds set a MINIMUM length for the yellow signal instead of a maximum.  If that is the case, then there should be no reason why the yellow arrow can't be set to a greater length - to match the time of the solid yellow.

Another problem I see is that most of the FYA signals are designed from the perspective of allowing a permissive turn.  This means that to avoid a yellow trap, the indications on the FYA 4 aspect signal should match the signal for opposing thru traffic.  FYA while opposing signal has green, yellow arrow while opposing signal has yellow, and red arrow while opposing signal has red.  THe time for the yellow arrow has to match what the opposing signal is doing. 

Worse, an uneven setup may cause people to watch the adjacent signal -which would be dangerous.  The whole point of FYA is that we are training drivers to ignore the adjacent signal and only focus on the FYA signal - since that is the only signal relevant to them.

[jakeroot]

Is it true that the 85th percentile speeds set a MINIMUM length for the yellow signal instead of a maximum.  If that is the case, then there should be no reason why the yellow arrow can't be set to a greater length - to match the time of the solid yellow.

Another problem I see is that most of the FYA signals are designed from the perspective of allowing a permissive turn.  This means that to avoid a yellow trap, the indications on the FYA 4 aspect signal should match the signal for opposing thru traffic.  FYA while opposing signal has green, yellow arrow while opposing signal has yellow, and red arrow while opposing signal has red.  THe time for the yellow arrow has to match what the opposing signal is doing. 

Worse, an uneven setup may cause people to watch the adjacent signal -which would be dangerous.  The whole point of FYA is that we are training drivers to ignore the adjacent signal and only focus on the FYA signal - since that is the only signal relevant to them.

The bolded bit seems to be the essence of it all.

Unfortunately, there's not much evidence that it's an actual requirement. It seems totally logical: right turn 'overlap' signals are timed perfectly with left turn green arrows; why not the same for FYA signals with opposing traffic? The only strict requirement seems to be that the yellow + red clearance interval begins at the same time; whether they end at the same time is apparently not a requirement. Or (possibly), it is a requirement, and most agencies think they've programmed it correctly, but actually haven't.

I think most agencies get the idea, since most left turn FYA signals that I see are timed correctly to end with through traffic, but these agencies may simply be going the extra mile by programming a yellow phase that lasts longer than strictly necessary for that lane, but which is actually true and proper as it aligns correctly with oncoming traffic.

[UCFKnights]

https://youtu.be/n1UobIzy7WE

This practice is actually quite common at left turn FYA signals in my area. The yellow for the FYA seems to last about a quarter second less than the through traffic. I assume it's an error since it should end simultaneous with through traffic, but it's a common error nonetheless.

I see around Reno all the time where the left yellow arrow and the through circular yellow don't terminate together. I thought it was weird when I first saw it, as my frame of reference was the Vegas area where the yellows do tend to terminate simultaneously. It can be weird if you're not used to it, but it's not necessarily an error. And I don't believe there is anything in the MUTCD that mandates the yellows terminate simultaneously.

Many jurisdictions follow the Institute of Traffic Engineers various formulas for signal phasing and indications. The ITE formula for the duration of a yellow clearance interval is a function of the 85th percentile speed (among other factors). I think some agencies use a slower turning speed for left turn movements than the speed limit of adjacent through movements, which may result in the difference in yellow intervals.

One possible issue may be with programming, and the possibility that most are set so that the solid yellow phase lasts the same time no matter if the solid yellow is after a green arrow (where 85th percentile speeds are relevant) or after a flashing yellow arrow (where the importance is more on 'make sure left turning traffic doesn't turn into oncoming traffic'). It would be appropriate to have a shorter yellow phase after the protected green phase, but not after the flashing yellow arrow phase. In my opinion, since left turn FYA signals are necessarily tied to through traffic, the solid yellow really should be tied to the through signals since, assuming the phase in question is after the permissive phase and when both through traffic and left turning traffic are about to face a red signal, traffic turning left must be certain that it is safe to finish their turn. The chance of an issue arising seems slim (probably is slim), but the potential is there.

Since we're talking about a small fraction of a second I don't think there is any real issue (you have to be prepared for red light runners in the first second no matter what when completing a permissive turn), but I'd say technically, it might make more sense to have the FYA phase end a second later then the opposing thru phase to discourage them from completing the turn too early during the possibility of the said red light runner. Never seen one programmed that way though

[mrsman]

https://youtu.be/n1UobIzy7WE

This practice is actually quite common at left turn FYA signals in my area. The yellow for the FYA seems to last about a quarter second less than the through traffic. I assume it's an error since it should end simultaneous with through traffic, but it's a common error nonetheless.

I see around Reno all the time where the left yellow arrow and the through circular yellow don't terminate together. I thought it was weird when I first saw it, as my frame of reference was the Vegas area where the yellows do tend to terminate simultaneously. It can be weird if you're not used to it, but it's not necessarily an error. And I don't believe there is anything in the MUTCD that mandates the yellows terminate simultaneously.

Many jurisdictions follow the Institute of Traffic Engineers various formulas for signal phasing and indications. The ITE formula for the duration of a yellow clearance interval is a function of the 85th percentile speed (among other factors). I think some agencies use a slower turning speed for left turn movements than the speed limit of adjacent through movements, which may result in the difference in yellow intervals.

One possible issue may be with programming, and the possibility that most are set so that the solid yellow phase lasts the same time no matter if the solid yellow is after a green arrow (where 85th percentile speeds are relevant) or after a flashing yellow arrow (where the importance is more on 'make sure left turning traffic doesn't turn into oncoming traffic'). It would be appropriate to have a shorter yellow phase after the protected green phase, but not after the flashing yellow arrow phase. In my opinion, since left turn FYA signals are necessarily tied to through traffic, the solid yellow really should be tied to the through signals since, assuming the phase in question is after the permissive phase and when both through traffic and left turning traffic are about to face a red signal, traffic turning left must be certain that it is safe to finish their turn. The chance of an issue arising seems slim (probably is slim), but the potential is there.

Since we're talking about a small fraction of a second I don't think there is any real issue (you have to be prepared for red light runners in the first second no matter what when completing a permissive turn), but I'd say technically, it might make more sense to have the FYA phase end a second later then the opposing thru phase to discourage them from completing the turn too early during the possibility of the said red light runner. Never seen one programmed that way though

And they really wouldn't be.  The goal is (or should be) matching the opposing thru signal.  Seeing a solid yellow arrow would be teh equivalent of seeing a yellow orb that warns you that the green phase is about to end and the red phase is about to begin.  If the yellow starts too late, there may not be enough warning time that the red phase is about to start.

If all of this argument is about fractions of a second, then it probably is not a big deal, anyway.