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Author Topic: Has the flashing yellow left turn signal made it to your state?  (Read 469779 times)

jakeroot

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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1926 on: November 04, 2021, 10:24:55 PM »

Comparing 2019 and 2021 GSV, looks like Virginia's gotten really gung-ho on replacing doghouses with FYAs in the past two years (I've only checked out Loudoun County so far). Reflective backplates seem to be flourishing as well. Can anyone in VA confirm this trend?
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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1927 on: November 05, 2021, 07:31:35 AM »

Yes VDOT is pretty much committed to both the FYA's and the yellow strip backplates on their roads. A lot of replacing have been going on lately around the state.

Some cities have been doing so with newer signals as well, most notably Richmond and Suffolk.
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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1928 on: November 10, 2021, 08:05:41 PM »

On my occasional work trip to Farmington, NM, I noticed they are starting to add FYAs to some intersections along NM-516 on the Northeast side of town.

Oddly (but then again, Anything in Farmington traffic-related is bizarre), all traffic lights at the new FYA intersections now are verdically displayed instead of the traditional NM horizontal setups on the overhead lights.

If there are other parts of New Mexico with FYAs, are all-vertical set-ups the standard practice???
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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1929 on: March 19, 2022, 03:17:51 PM »

Connecticut finally has a flashing yellow arrow.
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jakeroot

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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1930 on: March 19, 2022, 04:15:58 PM »

I love the promotional material that typically accompanies flashing yellow arrow installations (or at least did for a while). They act like it's the first type of signal to ever allow discretionary left turns.

Now it may be true that many of these have replaced fully protected left turns, but if they were looking to alleviate congestion, there have been ways to allow permissive lefts for as long as traffic lights have existed, and ways that included a protected phase for at least 50 years.
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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1931 on: March 19, 2022, 10:06:56 PM »

I love the promotional material that typically accompanies flashing yellow arrow installations (or at least did for a while). They act like it's the first type of signal to ever allow discretionary left turns.

Now it may be true that many of these have replaced fully protected left turns, but if they were looking to alleviate congestion, there have been ways to allow permissive lefts for as long as traffic lights have existed, and ways that included a protected phase for at least 50 years.

The reason why the flashing yellow arrow became necessary was a problem with five-section permissive heads called "yellow trap" that happened in configurations with a lead-lag left turn phase. Effectively, the direction that got the leading phase would have its green ball turn yellow, which would prompt those making a permissive left to make a left turn (as is normal on a yellow). However, oncoming traffic still had a green signal; the left-turners direction received a red signal because to allow the oncoming direction's left turn to receive a yellow signal. This would cause people to pull into oncoming traffic to make a left turn, with the assumption the traffic was stopped, only to be hit by cars that were given a green signal.

Flashing yellow arrow signals make lead-lag left turns safer, which is great, because lead-lag left turns are (as far as I know) the most efficient configuration. I don't know why we don't see more lead-lag left turn configurations though.

You also have to consider that flashing yellow arrow signals can serve as protected only signals for certain times of day, and can allow permissive left turns when the thru direction has a stop signal. These aren't possible on the traditional inline-five or doghouse, unless a very specific signal setup is laid out.

Pretty much, they're marketing the FYA so hard because people need to know how it works to take advantage of it. I personally like the inline five and doghouse signals, but the FYA just... does things they can't.

TLDR: The FYA signal isn't the first discretionary left turn device... it is an improvement on what we had that requires a little bit of education to understand.
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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1932 on: March 20, 2022, 09:16:58 PM »

Connecticut finally has a flashing yellow arrow.

Took them long enough.
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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1933 on: March 21, 2022, 09:08:04 AM »

PennDOT is still mainly using doghouses for left turns, at least in the Philly area.  This is true even for new installations.
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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1934 on: March 21, 2022, 03:43:16 PM »

I guess I don't understand how these fya's improve things. my understanding:

green ball with no arrow = go when safe
green arrow=you are protected, opposing is stopped
yellow arrow = protected phase ending
fya = go when safe

the only difference i see, is that if the opposite side has green+green arrow, my side will be red with fya, but it's rarely safe to turn during this phase.
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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1935 on: March 21, 2022, 04:16:11 PM »

I guess I don't understand how these fya's improve things. my understanding:

green ball with no arrow = go when safe
green arrow=you are protected, opposing is stopped
yellow arrow = protected phase ending
fya = go when safe

the only difference i see, is that if the opposite side has green+green arrow, my side will be red with fya, but it's rarely safe to turn during this phase.

In some areas they use lead-lag turn phases, for example, northbound left turns get a leading green arrow while southbound left turns get a lagging green arrow. The direction that gets the leading green arrow often also has the opportunity to turn left during the FYA associated with the oncoming green arrow phase, due to most of the straight through traffic having gone through by then.
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Has the flashing yellow left turn signal made it to your state?
« Reply #1936 on: March 21, 2022, 08:37:07 PM »

I guess I don't understand how these fya's improve things. my understanding:

green ball with no arrow = go when safe
green arrow=you are protected, opposing is stopped
yellow arrow = protected phase ending
fya = go when safe

the only difference i see, is that if the opposite side has green+green arrow, my side will be red with fya, but it's rarely safe to turn during this phase.
They’re great for engineers too.

Able to use time of day phasing so the signal can only give green arrow lefts at certain times of the day. Able to prevent yellow traps. And they give us benefits for protected right turns by delaying them so pedestrians get a head start


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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1937 on: March 22, 2022, 04:52:24 AM »

My main concern with this is the potential to condition motorists into only yielding if they see the flashing amber arrow. I know some places are using them where the left turn is permissive only and they need to be careful with that.

Also, if the aspect fails, there's the risk of false positive indications. If someone arrives at the intersection and sees only a yellow ball and then a red, with a signal head on the far left corner completely dark, there's your amber trap. Obviously, LED aspects are less likely to fail but it's not completely eliminated.
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Ted$8roadFan

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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1938 on: March 22, 2022, 06:06:01 AM »

They’ve made it to my state and my town. A major road rebuild has added them to intersections that really needed them. There are even a couple of flashing yellow right turn signals, shared with new bike lanes.
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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1939 on: March 22, 2022, 08:00:00 PM »

My main concern with this is the potential to condition motorists into only yielding if they see the flashing amber arrow. I know some places are using them where the left turn is permissive only and they need to be careful with that.

Also, if the aspect fails, there's the risk of false positive indications. If someone arrives at the intersection and sees only a yellow ball and then a red, with a signal head on the far left corner completely dark, there's your amber trap. Obviously, LED aspects are less likely to fail but it's not completely eliminated.

When I'm waiting in an intersection to turn left and the light goes to amber, I've always made a point of making sure opposing traffic was stopping before making the turn. That's just smart defensive driving.
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Amtrakprod

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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1940 on: March 22, 2022, 08:29:41 PM »

They’ve made it to my state and my town. A major road rebuild has added them to intersections that really needed them. There are even a couple of flashing yellow right turn signals, shared with new bike lanes.
Oh wow where is this ! That sounds interesting


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jakeroot

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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1941 on: March 22, 2022, 09:34:59 PM »

My main concern with this is the potential to condition motorists into only yielding if they see the flashing amber arrow. I know some places are using them where the left turn is permissive only and they need to be careful with that.

Also, if the aspect fails, there's the risk of false positive indications. If someone arrives at the intersection and sees only a yellow ball and then a red, with a signal head on the far left corner completely dark, there's your amber trap. Obviously, LED aspects are less likely to fail but it's not completely eliminated.

When I'm waiting in an intersection to turn left and the light goes to amber, I've always made a point of making sure opposing traffic was stopping before making the turn. That's just smart defensive driving.

I also make a point of this, even if the light is already red. There's usually a gap between the red light for one direction and the green light for the other, so there's no reason to immediately evacuate the intersection the moment the light turns amber.

Additionally, the problem with malfunctioning traffic signals (when it's not an intersection issue, but instead relegated to an individual head) is usually combated by using more than one signal for each movement. Not every state requires this for anything but the through movement, but it's a good practice to have more than one just in case. Overhead and on the far corner, ideally.
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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1942 on: March 22, 2022, 09:41:23 PM »

Able to use time of day phasing so the signal can only give green arrow lefts at certain times of the day.
And able to make them protected only in peak times. One reason why I like them over the doghouse or 5 section: more flexibility on the signal operation.
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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1943 on: March 23, 2022, 07:17:48 AM »

My main concern with this is the potential to condition motorists into only yielding if they see the flashing amber arrow. I know some places are using them where the left turn is permissive only and they need to be careful with that.

Also, if the aspect fails, there's the risk of false positive indications. If someone arrives at the intersection and sees only a yellow ball and then a red, with a signal head on the far left corner completely dark, there's your amber trap. Obviously, LED aspects are less likely to fail but it's not completely eliminated.

When I'm waiting in an intersection to turn left and the light goes to amber, I've always made a point of making sure opposing traffic was stopping before making the turn. That's just smart defensive driving.

And a minority pursuit, unfortunately. If everyone did that, we wouldn't need to worry about amber trap.
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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1944 on: March 24, 2022, 02:20:36 PM »

Able to use time of day phasing so the signal can only give green arrow lefts at certain times of the day.
And able to make them protected only in peak times. One reason why I like them over the doghouse or 5 section: more flexibility on the signal operation.
Exactly what I meant, yup !


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jakeroot

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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1945 on: March 24, 2022, 08:57:20 PM »

I love the promotional material that typically accompanies flashing yellow arrow installations (or at least did for a while). They act like it's the first type of signal to ever allow discretionary left turns.

Now it may be true that many of these have replaced fully protected left turns, but if they were looking to alleviate congestion, there have been ways to allow permissive lefts for as long as traffic lights have existed, and ways that included a protected phase for at least 50 years.

The reason why the flashing yellow arrow became necessary was a problem with five-section permissive heads called "yellow trap" that happened in configurations with a lead-lag left turn phase. Effectively, the direction that got the leading phase would have its green ball turn yellow, which would prompt those making a permissive left to make a left turn (as is normal on a yellow). However, oncoming traffic still had a green signal; the left-turners direction received a red signal because to allow the oncoming direction's left turn to receive a yellow signal. This would cause people to pull into oncoming traffic to make a left turn, with the assumption the traffic was stopped, only to be hit by cars that were given a green signal.

Flashing yellow arrow signals make lead-lag left turns safer, which is great, because lead-lag left turns are (as far as I know) the most efficient configuration. I don't know why we don't see more lead-lag left turn configurations though.

You also have to consider that flashing yellow arrow signals can serve as protected only signals for certain times of day, and can allow permissive left turns when the thru direction has a stop signal. These aren't possible on the traditional inline-five or doghouse, unless a very specific signal setup is laid out.

Pretty much, they're marketing the FYA so hard because people need to know how it works to take advantage of it. I personally like the inline five and doghouse signals, but the FYA just... does things they can't.

TLDR: The FYA signal isn't the first discretionary left turn device... it is an improvement on what we had that requires a little bit of education to understand.

I think I may not have fully explained my thoughts.

I understand why the FYA was created, it's certainly much more flexible in its deployment and operation than the traditional green ball setup (either fully permissive or protected-permissive using a four or five section signal with green and yellow arrows). But it's not a requirement for permissive left turns to "exist", per se.

For example, look at the tweet. The only point they make is that the flashing yellow arrow "alleviates traffic + queue time by allowing vehicles to turn when there is no traffic in the opposing direction". While that's true, if that was their only goal, they could have simply removed the old protected-only left turn signal heads that did not permit discretionary left turns, allowing for traffic turning left to simply proceed when safe at the same time as through traffic. If necessary, the left turn signals could have been replaced with four or five section left turn signals (aka, a "doghouse" or "tower") that would have also allowed for a protected phase in addition to the permissive phase.

I'm not trying to be pedantic here, I'm just trying to say that FYAs don't really bring anything new to the table unless you are looking for more complex setups (time of day phasing, free lefts during an oncoming green arrow, LPIs, etc). If the expressed purpose was simply to allow traffic to turn through gaps, well, they could have fixed that issue a long time ago.
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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1946 on: March 24, 2022, 10:24:28 PM »

The main point of the FYA is to have the flexible PPLT phasing with a dedicated left turn signal, without using the circular green indication over the left lane. That circular green tied to the adjacent green could cause the yellow trap issue (unless Dallas Phasing was used). FYA ends up being much more flexible and better understood.
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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1947 on: March 24, 2022, 10:38:45 PM »

The main point of the FYA is to have the flexible PPLT phasing with a dedicated left turn signal, without using the circular green indication over the left lane. That circular green tied to the adjacent green could cause the yellow trap issue (unless Dallas Phasing was used). FYA ends up being much more flexible and better understood.

But the flashing yellow arrow is not required for permissive left turns. That is, and remains, my only point.
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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1948 on: March 24, 2022, 10:55:59 PM »

The main point of the FYA is to have the flexible PPLT phasing with a dedicated left turn signal, without using the circular green indication over the left lane. That circular green tied to the adjacent green could cause the yellow trap issue (unless Dallas Phasing was used). FYA ends up being much more flexible and better understood.

...which is simply done by putting an overlap on the oncoming thru green, which can be a bit challenging if the controller you are programming has a very limited number of overlaps remaining and if there is limited space for more load switches for FYA... a signal tech told me it can be a bit challenging to get FYA's working with a TS1 controller/cabinet* compared to TS2 or ATC controllers (not sure how it is with 170-based controllers mostly used in the western US)

*Mention that because New Hampshire, even in some of their more recent installations or retrofits, still use TS1 equipment to this day

But the flashing yellow arrow is not required for permissive left turns. That is, and remains, my only point.

The new MUTCD continues to allow "yield on green" installations for approaches with a dedicated left turn lane using Permissive only or Permissive-Protected phasing, which I don't understand why this was kept in the new one and not deprecated by now... in my opinion, any kind of permissive left turn with a dedicated left turn lane should always have an overlap tied to the opposing greens using FYAs and not with the adjecent greens, since the left turns are not on the same rings under the old system which can cause yellow trap.
« Last Edit: April 11, 2022, 02:56:36 PM by fwydriver405 »
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Re: Has the flashing yellow left turn signal made it to your state?
« Reply #1949 on: March 24, 2022, 11:13:06 PM »

The main point of the FYA is to have the flexible PPLT phasing with a dedicated left turn signal, without using the circular green indication over the left lane. That circular green tied to the adjacent green could cause the yellow trap issue (unless Dallas Phasing was used). FYA ends up being much more flexible and better understood.

But the flashing yellow arrow is not required for permissive left turns. That is, and remains, my only point.
That's fair. If you're just having a permissive left with no need for protected left or anything else fancy, FYA doesn't bring anything extra to the table (aside from an all-arrow display).
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