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

[jeffandnicole]

Alright here's a brainstorm for everyone:

I recently heard a traffic engineer say he wasn't thrilled about lagging FYA lefts because a comment he hears: since most drivers around here are conditioned to expect leading lefts, drivers on the lagging turn assume they got "skipped" when the signal goes from red to FYA.  Would there be a way to communicate (preferably with the normal FYA signal heads) that "yes the controller knows you're here and you're going to get a protected Green arrow before the next red"?  I feel like this is solving a problem that doesn't really exist, but maybe it would help get more fans of FYA.

(P.S. I'm not trying to debate that lagging lefts are worthwhile - they're absolutely needed to improve two-way coordination)

If it's in an area that mostly locals will be driving, they'll eventually learn. But the best option is to do what drivers expect: Provide a leading green arrow.

[jakeroot]

I recently heard a traffic engineer say he wasn't thrilled about lagging FYA lefts because a comment he hears: since most drivers around here are conditioned to expect leading lefts, drivers on the lagging turn assume they got "skipped" when the signal goes from red to FYA.  Would there be a way to communicate (preferably with the normal FYA signal heads) that "yes the controller knows you're here and you're going to get a protected Green arrow before the next red"?  I feel like this is solving a problem that doesn't really exist, but maybe it would help get more fans of FYA.

I always thought this was a good thing. If you think you were skipped, you might actually be encouraged to try and find a gap. As opposed to those drivers who just sit and wait for the green arrow since they don't feel like turning through a gap.

In Vancouver, BC, it's common to disable the green arrow during off-peak hours since there is little operational advantage in providing a leading left in front of a few cars. It also increases the pedestrian walk cycle length. The traffic engineer in your story might lose his mind if he ever saw how things are up here.

[roadfro]

Alright here's a brainstorm for everyone:

I recently heard a traffic engineer say he wasn't thrilled about lagging FYA lefts because a comment he hears: since most drivers around here are conditioned to expect leading lefts, drivers on the lagging turn assume they got "skipped" when the signal goes from red to FYA.  Would there be a way to communicate (preferably with the normal FYA signal heads) that "yes the controller knows you're here and you're going to get a protected Green arrow before the next red"?  I feel like this is solving a problem that doesn't really exist, but maybe it would help get more fans of FYA.

(P.S. I'm not trying to debate that lagging lefts are worthwhile - they're absolutely needed to improve two-way coordination)

I'd be curious whether that same engineer has any 5-section PPLT displays where one side runs a lagging left, and how he feels about those. It's functionally the same thing, with again no readily-apparent indication that a protected left green arrow will come on at the end.

I can't really think of a way that existing signals can provide an "I see you" indication. You'd probably need a separate light element that could serve as a "call acknowledged" indicator (kinda like how on some newer pedestrian push buttons, an LED light illuminates after the button is pressed), but this probably would increase signal installation complexity and costs for insignificant gain. Like you said, solving a problem that doesn't really exist.

[johndoe]

the best option is to do what drivers expect: Provide a leading green arrow.

...please see the last sentence of my last post.  Leading lefts can not allow the ideal signal timing along corridors.

it's common to disable the green arrow during off-peak hours

truth - if it were up to me this would be more common around here.  This is just more about customer complaints- balancing getting more phone calls with slightly improved signal timing.

I'd be curious whether that same engineer has any 5-section PPLT displays where one side runs a lagging left, and how he feels about those. It's functionally the same thing, with again no readily-apparent indication that a protected left green arrow will come on at the end.

I can't really think of a way that existing signals can provide an "I see you" indication. You'd probably need a separate light element that could serve as a "call acknowledged" indicator (kinda like how on some newer pedestrian push buttons, an LED light illuminates after the button is pressed), but this probably would increase signal installation complexity and costs for insignificant gain. Like you said, solving a problem that doesn't really exist.

Sure, those exist (for instance at some diamond interchanges) and that engineer HAS some lagging FYA - it's just a con that he pointed out (see the customer complaint comment above)

It would be cool if all signal heads had an "I see you", maybe some sort of backplate illumination.  I wonder if there would be a way to do that really cheaply.

[Amtrakprod]

Alright here's a brainstorm for everyone:

I recently heard a traffic engineer say he wasn't thrilled about lagging FYA lefts because a comment he hears: since most drivers around here are conditioned to expect leading lefts, drivers on the lagging turn assume they got "skipped" when the signal goes from red to FYA.  Would there be a way to communicate (preferably with the normal FYA signal heads) that "yes the controller knows you're here and you're going to get a protected Green arrow before the next red"?  I feel like this is solving a problem that doesn't really exist, but maybe it would help get more fans of FYA.

(P.S. I'm not trying to debate that lagging lefts are worthwhile - they're absolutely needed to improve two-way coordination)

If it's in an area that mostly locals will be driving, they'll eventually learn. But the best option is to do what drivers expect: Provide a leading green arrow.

I disagree. Get them used to the new system. Lagging lefts are more efficient for everyone


iPhone

[jeffandnicole]

the best option is to do what drivers expect: Provide a leading green arrow.

...please see the last sentence of my last post.  Leading lefts can not allow the ideal signal timing along corridors.

You said we can't debate that, and I'm not. But there is a thing about driver expectations. Yes, standards change over time. And engineers that are used to doing it a certain way are often creatures of habit. If they aren't forced to change, they may not be willing to change.

So, an engineer has to decide...is it worth the trouble that may occur in additional accidents while motorists get used to a new system, or stick with what's tried and true, although signal progression may not be optimal?

Since motorists often take their current cues from watching cross traffic stop or their traffic lights change, that same cue from watching opposing traffic is a lot harder to determine.

[jakeroot]

So, an engineer has to decide...is it worth the trouble that may occur in additional accidents while motorists get used to a new system, or stick with what's tried and true, although signal progression may not be optimal?

Lead-lead signalization is not the only tried and true signal strategy. Many corridors across the US have used lead-lag signalization for years, if not decades. It's not a new thing, and neither are drivers feeling that they were skipped by a signal, permissive left or not, lead-lag or not. I genuinely don't understand how dropping lagging lefts would fix anything, since annoyed motorists are not really a thing that needs fixing.

I don't really understand what you mean by "additional accidents". Lead-lag causes more accidents while drivers get used to...waiting for a green arrow? Where have you witnessed this? The most I've witnessed is the occasional red light run as drivers think they were skipped and just turn through a gap anyways.

[SkyPesos]

Lead-lag is pretty common with left turns I've seen in the St Louis area, both protected and protected/permissive. If you drive through an area frequently, it's easy to tell which side gets the leading left, and which side gets the lagging left, as it's generally consistent.

[fwydriver405]

Lead-lag is pretty common with left turns I've seen in the St Louis area, both protected and protected/permissive. If you drive through an area frequently, it's easy to tell which side gets the leading left, and which side gets the lagging left, as it's generally consistent.

In some places near my hometown, like South Portland, also both with protected only and beginning with FYA, on some corridors during the weekday rush hour, the lead-lag alternates depending on the time of day. IIRC, the peak direction gets the leading left and the non-peak direction gets the lagging left, but not sure if that is true or flipped around. Not sure if this kind of time of day lead-lag is common in other cities.

[johndoe]

@jeffandnicole: true, well said

... it's easy to tell which side gets the leading left, and which side gets the lagging left, as it's generally consistent.

... the lead-lag alternates depending on the time of day. IIRC, the peak direction gets the leading left and the non-peak direction gets the lagging left, but not sure if that is true or flipped around.

From what I've seen it's more about ensuring the two mainroad straight movements get "green bands" through the whole corridor (don't have to stop of they keep going straight).  So based on the cycle length (which is based on overall volumes) the lefts are really an afterthought, dictated by those straight platoons.  Sometimes the busy left will lead, sometimes lag.  But generally leading one and lagging the other makes those straight movements stop the least (depending on space to next signal, speed limit, etc). So certain times of day it may make most sense for the same movement to lead and later in the day lag.

[MASTERNC]

https://connect.ncdot.gov/resources/safety/Teppl/TEPPL%20All%20Documents%20Library/T71_DLFYA.PDF

Will they really consider this?

They already do it for right turns

https://www.google.com/maps/@36.0347242,-79.9643721,3a,49.2y,318.33h,88t/data=!3m6!1e1!3m4!1spBhiJOBhI4Xk5e9ohyLgJw!2e0!7i13312!8i6656

[kphoger]

I recently heard a traffic engineer say he wasn't thrilled about lagging FYA lefts because a comment he hears: since most drivers around here are conditioned to expect leading lefts, drivers on the lagging turn assume they got "skipped" when the signal goes from red to FYA.  Would there be a way to communicate (preferably with the normal FYA signal heads) that "yes the controller knows you're here and you're going to get a protected Green arrow before the next red"?  I feel like this is solving a problem that doesn't really exist, but maybe it would help get more fans of FYA.

I always thought this was a good thing.

My first thought was actually, "Who cares if drivers think they were skipped?"

Either (a) they find a gap and it doesn't matter, or else (b) the green arrow eventually comes and they find out they weren't skipped.

[tolbs17]

https://connect.ncdot.gov/resources/safety/Teppl/TEPPL%20All%20Documents%20Library/T71_DLFYA.PDF

Will they really consider this?

They already do it for right turns

https://www.google.com/maps/@36.0347242,-79.9643721,3a,49.2y,318.33h,88t/data=!3m6!1e1!3m4!1spBhiJOBhI4Xk5e9ohyLgJw!2e0!7i13312!8i6656

Never seen that here, at least not in my area. We don't have double right turn lanes except for going to Washington.

[kphoger]

https://connect.ncdot.gov/resources/safety/Teppl/TEPPL%20All%20Documents%20Library/T71_DLFYA.PDF

Will they really consider this?

They already do it for right turns

https://www.google.com/maps/@36.0347242,-79.9643721,3a,49.2y,318.33h,88t/data=!3m6!1e1!3m4!1spBhiJOBhI4Xk5e9ohyLgJw!2e0!7i13312!8i6656

Never seen that here, at least not in my area. We don't have double right turn lanes except for going to Washington.

I'm confused.  Have you not seen it in your area?  Or have you seen it "going to Washington"?

[johndoe]

I recently heard a traffic engineer say he wasn't thrilled about lagging FYA lefts because a comment he hears: since most drivers around here are conditioned to expect leading lefts, drivers on the lagging turn assume they got "skipped" when the signal goes from red to FYA.  Would there be a way to communicate (preferably with the normal FYA signal heads) that "yes the controller knows you're here and you're going to get a protected Green arrow before the next red"?  I feel like this is solving a problem that doesn't really exist, but maybe it would help get more fans of FYA.

I always thought this was a good thing.

My first thought was actually, "Who cares if drivers think they were skipped?"

The traffic engineer who has to answer the phone call complaints, apparently!

[SkyPesos]

Speaking of FYA right turns, I don't really like them (while I like FYAs for left turns), and would prefer the traditional 5-section or doghouse for right turns. FYAs seem less useful for right turns to me compared to for left turns.

[SignBridge]

New York City uses FYA on some right turns to protect bikes lanes and crosswalks. Unconventional but still effective applications.

[Amtrakprod]

Speaking of FYA right turns, I don't really like them (while I like FYAs for left turns), and would prefer the traditional 5-section or doghouse for right turns. FYAs seem less useful for right turns to me compared to for left turns.

That doesn't make sense. Maybe you just live in a rural area. We use FYA right turns for LPIs and to make sure people yield to pedestrians and bicycles.


iPhone

[SkyPesos]

Speaking of FYA right turns, I don't really like them (while I like FYAs for left turns), and would prefer the traditional 5-section or doghouse for right turns. FYAs seem less useful for right turns to me compared to for left turns.

That doesn't make sense. Maybe you just live in a rural area. We use FYA right turns for LPIs and to make sure people yield to pedestrians and bicycles.


iPhone

It's suburban actually, but rural is close enough for my area  . Also Ohio doesn't really use FYAs in general, except a couple one-offs and a section of OH 747.

Though aren't right turns supposed to yield to pedestrians/oncoming traffic with a generic green ball anyways? Maybe a FYA RT could work as a reassurance, but it takes away from the two required straight arrows or green balls each signal layout needs that a doghouse or 5-section can provide. MoDOT is an agency I can think of that uses FYA lefts in combination with doghouse or 5-section rights.

[Amtrakprod]

Speaking of FYA right turns, I don't really like them (while I like FYAs for left turns), and would prefer the traditional 5-section or doghouse for right turns. FYAs seem less useful for right turns to me compared to for left turns.

That doesn't make sense. Maybe you just live in a rural area. We use FYA right turns for LPIs and to make sure people yield to pedestrians and bicycles.


iPhone

It's suburban actually, but rural is close enough for my area  . Also Ohio doesn't really use FYAs in general, except a couple one-offs and a section of OH 747.

Though aren't right turns supposed to yield to pedestrians/oncoming traffic with a generic green ball anyways? Maybe a FYA RT could work as a reassurance, but it takes away from the two required straight arrows or green balls each signal layout needs that a doghouse or 5-section can provide. MoDOT is an agency I can think of that uses FYA lefts in combination with doghouse or 5-section rights.

Not really. And I mean the flashing yellow arrow really enforces the idea of yielding.

Plus it's nicer when doing a LPI to only have to delay turning traffic


iPhone

[mrsman]

Speaking of FYA right turns, I don't really like them (while I like FYAs for left turns), and would prefer the traditional 5-section or doghouse for right turns. FYAs seem less useful for right turns to me compared to for left turns.

That doesn't make sense. Maybe you just live in a rural area. We use FYA right turns for LPIs and to make sure people yield to pedestrians and bicycles.


iPhone

It's suburban actually, but rural is close enough for my area  . Also Ohio doesn't really use FYAs in general, except a couple one-offs and a section of OH 747.

Though aren't right turns supposed to yield to pedestrians/oncoming traffic with a generic green ball anyways? Maybe a FYA RT could work as a reassurance, but it takes away from the two required straight arrows or green balls each signal layout needs that a doghouse or 5-section can provide. MoDOT is an agency I can think of that uses FYA lefts in combination with doghouse or 5-section rights.

Not really. And I mean the flashing yellow arrow really enforces the idea of yielding.

Plus it's nicer when doing a LPI to only have to delay turning traffic


iPhone

Right.  just to expound on the above, the LPI, leading pedestrian interval, basically means that the signal will give the pedestrians (and/or bikes) a head start on their green before parallel traffic gets a green.

It works especially well in areas with heavy ped use, and heavy use of no turn on red at such corners.  (Think NYC). 

THe simple way of doing an LPI, is to simply allow the "walk' signal to come on while all the vehicle signals are red and then a few seconds later releasing the green signal.  This provides peds a head start on the crossing and presumably by the time that any car wants to turn right (when they get a green) the ped is more visible and already in the middle of the intersection.

The problem with the above is that all traffic is held during those few seconds, when it is likely only the turning trafffic that poses the danger to pedestrians.  it would be nice if thru traffic can go at the beginning of the signal and right turners are released a few seconds later.  A more deluxe LPI signal utilizing the FYA signal will allow for that.*  Walk and green orb can come on at the same time, while right turners face a red arrow.  A few seconds later, the right turners face a FYA.  They may turn right, but they must YIELD to the peds who may still be in the intersection.


*Technically, depending on the state, it is true that if there were a red arrow to prohibit right turns and then those right turns vanish (i.e. other than the red arrow, there is no yellow or green arrow), you are left with a green orb which will permit you to turn while yielding to peds.  This is how LPIs are done in Downtown Baltimore -- MD does not seem to allow the FYA signal in any context. 

Here is a one way left to one way left in Downtown Baltimore, the corner of Sharp and Pratt.  In almost every state, a one way left to one way left is similar to a right turn in that they can be made on red (unless prohibited by sign) and that the turn is made by staying close to the corner.  This is a good corner for LPI, since it is downtown, with lots of peds, and this is a double turn lane, indicating heavy turning traffic.

In the beginning, the signal is red.  Left turners see a red arrow and straight traffic sees a red orb.  [The double red orb is an anomaly, not relevant to the present discussion.  There should be two thru signals here per MUTCD, but I guess there is no room, so they put in one signal with two reds instead.  (This is common in Baltimore for RYG arrow signals, if there is only one signal head the signal is RRYG.)]  No turn on red sign prominently displayed.

https://www.google.com/maps/@39.286361,-76.6175269,3a,75y,171.3h,93.6t/data=!3m6!1e1!3m4!1s_sA1ZPRkBjq4UIbDIhaykQ!2e0!7i16384!8i8192

Straight traffic is released with a straight green arrow, but left turners cannot turn because of the red arrow.  An LPI in action:

https://www.google.com/maps/@39.2866683,-76.617631,3a,15y,170.02h,87.6t/data=!3m6!1e1!3m4!1sWdeI_sxa7eCxEwVlQVAgjQ!2e0!7i16384!8i8192

A few seconds later, left turns are permitted, but still must yield to peds.  This is why the left turning traffic will see a green ball instead of a green arrow.  [A green arrow would imply protected turn, but it is not a protected turn because pedestrians may be present.]

https://www.google.com/maps/@39.2864704,-76.6175509,3a,75y,181.07h,84.24t/data=!3m6!1e1!3m4!1suzRZnyeyGBmfmMHX_izDtA!2e0!7i16384!8i8192

So while a FYA is better IMO, Baltimore shows us that a deluxe LPI is possible without using the FYA.

[tolbs17]

https://connect.ncdot.gov/resources/safety/Teppl/TEPPL%20All%20Documents%20Library/T71_DLFYA.PDF

Will they really consider this?

They already do it for right turns

https://www.google.com/maps/@36.0347242,-79.9643721,3a,49.2y,318.33h,88t/data=!3m6!1e1!3m4!1spBhiJOBhI4Xk5e9ohyLgJw!2e0!7i13312!8i6656

Never seen that here, at least not in my area. We don't have double right turn lanes except for going to Washington.

I'm confused.  Have you not seen it in your area?  Or have you seen it "going to Washington"?

No.

[roadfro]

Here is a one way left to one way left in Downtown Baltimore, the corner of Sharp and Pratt.  In almost every state, a one way left to one way left is similar to a right turn in that they can be made on red (unless prohibited by sign) and that the turn is made by staying close to the corner.  This is a good corner for LPI, since it is downtown, with lots of peds, and this is a double turn lane, indicating heavy turning traffic.

In the beginning, the signal is red.  Left turners see a red arrow and straight traffic sees a red orb.  [The double red orb is an anomaly, not relevant to the present discussion.  There should be two thru signals here per MUTCD, but I guess there is no room, so they put in one signal with two reds instead.  (This is common in Baltimore for RYG arrow signals, if there is only one signal head the signal is RRYG.)]  No turn on red sign prominently displayed.

https://www.google.com/maps/@39.286361,-76.6175269,3a,75y,171.3h,93.6t/data=!3m6!1e1!3m4!1s_sA1ZPRkBjq4UIbDIhaykQ!2e0!7i16384!8i8192

Straight traffic is released with a straight green arrow, but left turners cannot turn because of the red arrow.  An LPI in action:

https://www.google.com/maps/@39.2866683,-76.617631,3a,15y,170.02h,87.6t/data=!3m6!1e1!3m4!1sWdeI_sxa7eCxEwVlQVAgjQ!2e0!7i16384!8i8192

A few seconds later, left turns are permitted, but still must yield to peds.  This is why the left turning traffic will see a green ball instead of a green arrow.  [A green arrow would imply protected turn, but it is not a protected turn because pedestrians may be present.]

https://www.google.com/maps/@39.2864704,-76.6175509,3a,75y,181.07h,84.24t/data=!3m6!1e1!3m4!1suzRZnyeyGBmfmMHX_izDtA!2e0!7i16384!8i8192

So while a FYA is better IMO, Baltimore shows us that a deluxe LPI is possible without using the FYA.

That seems like a good operation for LPI. It seems real awkward though to run that with a shared left/thru lane, and the signal head types doesn't seem to be MUTCD-kosher. But I can't think of a better way to do it without changing the lane layout.

[jakeroot]

Given the shared-lane design, I would personally opt to have only one overhead signal and one on the right.

I would use a 5-section display, and operate it like this:

(1) red orb + green up arrow (LPI)
(2) flashing yellow left arrow + green up arrow
(3) green left arrow + green up arrow (if necessary)

[tolbs17]

replying to my comment, apparently they have one here in Wendell.

https://www.google.com/maps/@35.7834961,-78.4423108,3a,15y,293.7h,95.85t/data=!3m7!1e1!3m5!1s59nXg2XDDmkyDqrjLTafHQ!2e0!5s20160401T000000!7i13312!8i6656