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

[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.

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.

The yellow time should absolutely be timed to the exact length of the through signal's yellow phase. The FYA is intrinsically tied to the state of oncoming traffic. To then allow different yellow times misses the point: it needs to echo 100% the state of the oncoming signal, including responding down to [ideally] the millisecond when there is a phase change.

Realistically, yeah, a quarter second doesn't mean much. But it shouldn't be allowed simply on principle.

The 85th percentile speeds for the approach to a left turn whose lane likely begins only a few hundred feet earlier seems completely irrelevant, for the record. Just use the yellow times for the through signal.

[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

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.

Yes, I'm not saying reduce the yellow phase beyond the normal amount, but the FYA and the related yellow arrow could terminate a second after the opposing thru signal, allowing left turn traffic to clear with less concern of a conflicting red light runner. Much like how many areas have implemented LPIs instead of making sure that the green and walk signal come on at the exact same time. Adding a second or 2 there can increase safety

[STLmapboy]

Already posted about this in traffic signals, but it pertains to this thread too.

I found an interesting FYA setup in Midland, TX, on a fairly recent signal. There's a 3-section permissive only left turn FYA (with the red signal being a ball) and a five-section signal with a sign that says "thru proceed on flashing yellow." The signal setup is fairly new (I'd say 2016 or so). How would this work?

[fwydriver405]

I wasn't sure if I should post this to this thread or the "double permissive left" thread but there are intersections in Cary and Clayton NC that will use variable lane use control for a double left turn lane... Protected only during rush hour with two left turning lanes, and PPLT all other times with only single left-turn lane.

Any similar installs anywhere else? Plenty of double turning lanes near my area that don't really need to have Protected only phasing and both LT lanes during the off-peak...

https://abc11.com/dynamic-left-turn-cary-clayton-traffic/5918367/

[jakeroot]

I wasn't sure if I should post this to this thread or the "double permissive left" thread but there are intersections in Cary and Clayton NC that will use variable lane use control for a double left turn lane... Protected only during rush hour with two left turning lanes, and PPLT all other times with only single left-turn lane.

Any similar installs anywhere else? Plenty of double turning lanes near my area that don't really need to have Protected only phasing and both LT lanes during the off-peak...

https://abc11.com/dynamic-left-turn-cary-clayton-traffic/5918367/

I believe there's been a couple other installs elsewhere in North Carolina.

Couple problems that I've noticed:

(1) to avoid blanking out an entire signal, only one signal is used, even when both turn lanes are operational. This is not desirable for a double left turn. An extra FYA signal should be mounted on the far left corner of the intersection (either on an existing mast or a separate pole) to account for this.

(2) (the bigger one) there is very high levels of ignorance with regard to the operation of the closed lane. Chiefly, drivers using both lanes during off-peak hours when the FYA is active.

I would prefer that the left turn were designed to allow protected/permissive operation throughout the day with both lanes operational 24/7, with protected-only phasing perhaps during peak hours. It would be far less confusing for drivers.

[fwydriver405]

I believe there's been a couple other installs elsewhere in North Carolina.

Couple problems that I've noticed:

(1) to avoid blanking out an entire signal, only one signal is used, even when both turn lanes are operational. This is not desirable for a double left turn. An extra FYA signal should be mounted on the far left to account for this.

When you say that, do you mean the 2nd FYA signal should be post mounted to the left, like this, similar to what CA does?

(2) (the bigger one) there is very high levels of ignorance with regard to the operation of the closed lane. Chiefly, drivers using both lanes during off-peak hours when the FYA is active.

Yeah that's what I thought... the lane configuration might confuse some drivers who are used to using both lanes to turn left... at this point, I would have evaluated having a double permissive left w/TOD phasing instead of this solution. I'm guessing they chose to operate the single permissive left like if the turn lane had positive offset...

Would you have to change the striping to make the configuration less confusing? In my view that just seems to add more "hoops" than if they were to use TOD double permissive left...

[jakeroot]

When you say that, do you mean the 2nd FYA signal should be post mounted to the left, like this, similar to what CA does?

Exactly what I meant, yes. The second signal has two purposes: provides two left turn signals, which should be a minimum for a double left turn, but also allows the signal to operate in single-lane mode without two overhead signals confusing drivers into thinking both left turn lanes are active. I edited my post above to clarify this.

(2) (the bigger one) there is very high levels of ignorance with regard to the operation of the closed lane. Chiefly, drivers using both lanes during off-peak hours when the FYA is active.

Yeah that's what I thought... the lane configuration might confuse some drivers who are used to using both lanes to turn left... at this point, I would have evaluated having a double permissive left w/TOD phasing instead of this solution. I'm guessing they chose to operate the single permissive left like if the turn lane had positive offset...

Would you have to change the striping to make the configuration less confusing? In my view that just seems to add more "hoops" than if they were to use TOD double permissive left...

I find most jurisdictions are very cautious with using double permissive left turns, even if there is ample opportunity to design the intersection for maximum visibility. The cities that use it here in WA have a design policy where the oncoming left turn is offset to improve visibility.

Still, given that NC's project here certainly required some research and outreach, they could have taken the time to at least consider the benefits of a properly-designed double permissive FYA setup. After all, I'm already seeing a lot of drivers using that second lane during the permissive phase, and it doesn't seem like crashes are occurring. But they are breaking the law, which is perhaps unfair to drivers who are rightfully confused by the setup, and who are otherwise turning safely and following the FYA signal.

[paulthemapguy]

I don't know if I'm late to the party here, but IDOT District 5 has these new FYA's along IL-1 just south of I-74 (Danville area).  Also, what is up with these backplates?--


IL-YT by Paul Drives, on Flickr

[Amtrakprod]

What in gods name are those back plates


iPhone

[plain]

I can't even come up with a name for those backplates.. I've never seen anything like that. I'm wondering if they were designed like that for wind resistance or something? And are they reflective?

[mrsman]

It seems to defeat one of the main purposes of backplates, namely blocking out the sun so that you can clearly see the signal.  I don't understand it.

[Revive 755]

It's a further evolution of the backplates with large slots found in Lincoln, IL?

[SignBridge]

Notice how the backplate on the center head is partly broken away? Eventually the rest of it will fall away too. Happens all the time on Long Island with NYS DOT's signals. Eventually most of them disappear.

[STLmapboy]

I imagine those large gaps will not help the durability of those backplates 

Illinois really is...cutting around the edges.

[NoGoodNamesAvailable]

Notice how the backplate on the center head is partly broken away? Eventually the rest of it will fall away too. Happens all the time on Long Island with NYS DOT's signals. Eventually most of them disappear.

I have noticed this in region 8 as well. NYSDOT's mast arm installations look very shoddy in general... I saw that they were increasing the thickness of the backplates in the new specifications, hopefully that fixes the issue.

[fwydriver405]

If an FYA is used for a right turn signal, would it cause yellow trap for the oncoming left turn(s) if the FYA right turn signal(s) continued to flash yellow, while the permissive left turns are terminating? At this intersection, for the right turn overlap, the FYA continues to flash yellow arrow during the yellow change phase, then turns green when the Main St traffic gets their left green arrow.

Weymouth MA, Main and Pond St:

[jakeroot]

If an FYA is used for a right turn signal, would it cause yellow trap for the oncoming left turn(s) if the FYA right turn signal(s) continued to flash yellow, while the permissive left turns are terminating? At this intersection, for the right turn overlap, the FYA continues to flash yellow arrow during the yellow change phase, then turns green when the Main St traffic gets their left green arrow.

Weymouth MA, Main and Pond St:

That is very interesting.

Proper protocol would be to terminate the permissive phases together, and then enable the solid green arrow after the all-red phase. Presently, oncoming traffic would be trapped by traffic turning right, who is not required to yield to them during the FYA phase, and certainly not during the green arrow phase.

The catch is that right-facing FYA signals are sometimes used in ways that make those turning right yield to everyone else, including those from the left. I've only seen this setup at slip lanes, personally. At any rate, this seems to work fine as most drivers can work out that they have to yield to everyone in these situations (although a supplementary "yield to all traffic on [fya]" sign would be helpful), but at a regular four-way intersection, this isn't how it works.

[mrsman]

If an FYA is used for a right turn signal, would it cause yellow trap for the oncoming left turn(s) if the FYA right turn signal(s) continued to flash yellow, while the permissive left turns are terminating? At this intersection, for the right turn overlap, the FYA continues to flash yellow arrow during the yellow change phase, then turns green when the Main St traffic gets their left green arrow.

Weymouth MA, Main and Pond St:

That is very interesting.

Proper protocol would be to terminate the permissive phases together, and then enable the solid green arrow after the all-red phase. Presently, oncoming traffic would be trapped by traffic turning right, who is not required to yield to them during the FYA phase, and certainly not during the green arrow phase.

The catch is that right-facing FYA signals are sometimes used in ways that make those turning right yield to everyone else, including those from the left. I've only seen this setup at slip lanes, personally. At any rate, this seems to work fine as most drivers can work out that they have to yield to everyone in these situations (although a supplementary "yield to all traffic on [fya]" sign would be helpful), but at a regular four-way intersection, this isn't how it works.

The FYA could have multiple meanings.  It generally means a turn requiring a yield, but the big question is yielding to whom.  I agree with jakeroot that in this circumstance it would be far better to terminate the FYA so as to avoid conflict with opposing lefts.  i agree that in this circumstance (and in most cases utilizing the FYA for rights) the FYA can lead drivers to mean that they have a protected turn with respect to traffic, but they need to yield to pedestrians.  It is not wise to change the meaning of the same signal indication within the same intersection.

Given that the change from green orb to yellow orb to all red to cross street green arrow is a short amount of time - there is no real problem to terminate the FYA to red before allowing the green arrow to corresponde with the cross street left.  It is the safest course of action.

So I would say in a standard intersection, with right turns controlled with a 4 aspect signal with FYA, that the FYA is used at the same time as green orb to warn of the need to yield to parallel pedestrians.  With the yellow orb, a solid yellow arrow.  A brief all red and then a right green arrow during the cross traffic left.  A yellow arrow corresponding with the cross street left yellow.  And when cross traffic is released, a flashing red arrow to denote the need to stop and yield to traffic on the left.  Since it is a separare indication, drivers are aware to watch for something different than during the FYA.

[UCFKnights]

If an FYA is used for a right turn signal, would it cause yellow trap for the oncoming left turn(s) if the FYA right turn signal(s) continued to flash yellow, while the permissive left turns are terminating? At this intersection, for the right turn overlap, the FYA continues to flash yellow arrow during the yellow change phase, then turns green when the Main St traffic gets their left green arrow.

Weymouth MA, Main and Pond St:

That is very interesting.

Proper protocol would be to terminate the permissive phases together, and then enable the solid green arrow after the all-red phase. Presently, oncoming traffic would be trapped by traffic turning right, who is not required to yield to them during the FYA phase, and certainly not during the green arrow phase.

The catch is that right-facing FYA signals are sometimes used in ways that make those turning right yield to everyone else, including those from the left. I've only seen this setup at slip lanes, personally. At any rate, this seems to work fine as most drivers can work out that they have to yield to everyone in these situations (although a supplementary "yield to all traffic on [fya]" sign would be helpful), but at a regular four-way intersection, this isn't how it works.

The FYA could have multiple meanings.  It generally means a turn requiring a yield, but the big question is yielding to whom.  I agree with jakeroot that in this circumstance it would be far better to terminate the FYA so as to avoid conflict with opposing lefts.  i agree that in this circumstance (and in most cases utilizing the FYA for rights) the FYA can lead drivers to mean that they have a protected turn with respect to traffic, but they need to yield to pedestrians.  It is not wise to change the meaning of the same signal indication within the same intersection.

Given that the change from green orb to yellow orb to all red to cross street green arrow is a short amount of time - there is no real problem to terminate the FYA to red before allowing the green arrow to corresponde with the cross street left.  It is the safest course of action.

So I would say in a standard intersection, with right turns controlled with a 4 aspect signal with FYA, that the FYA is used at the same time as green orb to warn of the need to yield to parallel pedestrians.  With the yellow orb, a solid yellow arrow.  A brief all red and then a right green arrow during the cross traffic left.  A yellow arrow corresponding with the cross street left yellow.  And when cross traffic is released, a flashing red arrow to denote the need to stop and yield to traffic on the left.  Since it is a separare indication, drivers are aware to watch for something different than during the FYA.

The pedestrian phase should be ending at the same time as well for the very same reason, to avoid yellow trap.

FYA, like all flashing yellow traffic signals, always has a single identical meaning: Use caution. This movement is uncontrolled at this time, follow normal traffic rules. If you removed the traffic signal entirely, it should make no difference to any yielding requirements.

[mrsman]

^^^^^^

I agree.  Even though the MUTCD does allow for other options, IMO FDW must end prior to yellow ball so that we don't have a yellow trap problem for peds. 

While I also agree that the flashing yellow strictly means caution, its use at intersections will dictate how it is perceived by other drivers.  For left turns on 2 way streets, it is almost universally used to denote a caution condition for permissive lefts, to yield to opposing traffic, independent of what parallel same direction traffic is doing.

In a similar way, in the intersection we've been discussing, the concern is that the FYA is only warning of the pedestrian yield condition, not the vehicle yield condition.   Since the delay is not great, it seems to meet that concern, it would be wise to terminate the FYA signal during the yellow orb phase so that there is time for the left turns to go.

[UCFKnights]

^^^^^^

I agree.  Even though the MUTCD does allow for other options, IMO FDW must end prior to yellow ball so that we don't have a yellow trap problem for peds. 

While I also agree that the flashing yellow strictly means caution, its use at intersections will dictate how it is perceived by other drivers.  For left turns on 2 way streets, it is almost universally used to denote a caution condition for permissive lefts, to yield to opposing traffic, independent of what parallel same direction traffic is doing.

In a similar way, in the intersection we've been discussing, the concern is that the FYA is only warning of the pedestrian yield condition, not the vehicle yield condition.   Since the delay is not great, it seems to meet that concern, it would be wise to terminate the FYA signal during the yellow orb phase so that there is time for the left turns to go.

I just think its important to stop associating the FYA with meaning yield since... it doesn't mean that. Vehicles turning right have the right of way to complete their turn before those making a left onto the same street. Thats precisely why this signal setup is an issue.

[jakeroot]

I just think its important to stop associating the FYA with meaning yield since... it doesn't mean that. Vehicles turning right have the right of way to complete their turn before those making a left onto the same street. Thats precisely why this signal setup is an issue.

Vehicles turning right have the right-of-way over vehicles turning left, but do not have the right-of-way over pedestrians. This is a basic rule of law. This setup does not conflict with that.

I don't understand the concept of FYA not meaning "yield". It denotes a permissive movement, which requires yielding the right-of-way to complete. Who one yields to is another issue.

[Pete from Boston]

What is the protocol for a green arrow to transition to a flashing yellow arrow? I was just at an intersection where the green arrow went to a steady yellow arrow, then a red arrow for maybe one second before changing to flashing yellow.

Of course I slammed on my brakes for an instant at the red arrow, which was needless and potentially dangerous. Seems to me like it could have gone from steady yellow to flashing yellow just fine.

At the end of the phase, it went from flashing yellow arrow directly to red arrow. There was no steady yellow in between. That also seems like a mistake.

[3467]

Illinois does and my screeching brakes were not as lucky as Pete's.

[jeffandnicole]

What is the protocol for a green arrow to transition to a flashing yellow arrow? I was just at an intersection where the green arrow went to a steady yellow arrow, then a red arrow for maybe one second before changing to flashing yellow.

Of course I slammed on my brakes for an instant at the red arrow, which was needless and potentially dangerous.

Stopping at a red light is dangerous?  I'd contact your elected officials about that one.

What would you have done if the red arrow stayed red?  You knew the yellow arrow traditionally means that a red light would be forthcoming.  Sounds like you were trying to beat the light and second-guessed yourself.

Would you have been more satisfied if the red light stayed red for 5 seconds, then the FYA appeared? 

While I know the point your making is the arrow should've just gone from steady yellow to flashing yellow, the entire reason the FYA exists is to allow for varying modes of operation, so one should never assume a steady yellow arrow will instantly be followed by a flashing yellow arrow.