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

Started by NJRoadfan, June 17, 2010, 10:58:35 AM

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jakeroot

Quote authors mixed up...fixed here but you may want to fix your post...

Quote from: fwydriver405 on March 24, 2022, 10:55:59 PM
Quote from: jakeroot on March 24, 2022, 10:38:45 PM
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.

If you are implying that every intersection with a dedicated left turn lane should have, at the very least, a permissive-only FYA, I feel like that may be a bit overkill. There are plenty of intersections where there is no need for any protected phasing. In those cases, yes, a permissive-only FYA wouldn't hurt. But I also don't think it's strictly necessary.


jeffandnicole

Quote from: fwydriver405 on March 24, 2022, 10:55:59 PM...since the left turns are not on the same rings under the old system which can cause yellow trap.

Yellow traps are caused when the opposing direction has an extended green, which occurs quite rarely.

Even intersections with FLAs often have cross traffic with traditional RYG lights.

Amtrakprod

Quote from: jakeroot on March 24, 2022, 08:57:20 PM
Quote from: Hobart on March 19, 2022, 10:06:56 PM
Quote from: jakeroot 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.

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.
Exactly. Something like this signal: https://youtu.be/vtoSU-NBywM


iPhone
Roadgeek, railfan, and crossing signal fan. From Massachusetts, and in high school. Youtube is my website link. Loves FYAs signals. Interest in Bicycle Infrastructure. Owns one Leotech Pedestrian Signal, and a Safetran Type 1 E bell.

jakeroot

Quote from: Amtrakprod on March 26, 2022, 08:04:53 AM
Exactly. Something like this signal: https://youtu.be/vtoSU-NBywM

That's definitely the longest LPI I have ever seen.

Side-note: love the walk timers being on for the entire walk phase. I've only seen this in DC, where it's everywhere and I think it's so cool. Too bad it's "not allowed".

Mr. Matté

Quote from: Mr. Matté on June 13, 2020, 05:05:00 PM
Well, I think I spotted a flashing yellow arrow in New Jersey today!

It's for a right turn when a yield sign could probably be more than sufficient: CR 529 / Ethel Road in Piscataway, GSV from before its activation: https://www.google.com/maps/@40.5333027,-74.4194722,3a,47.5y,200.7h,87.04t/data=!3m6!1e1!3m4!1sgqw481rS8VoiDYIoC5TCiQ!2e0!7i16384!8i8192

So I was incorrect, in my drives this weekend I found another flashing yellow in the Garden State that dates back to around 2013 in North Bergen, though it operates the same way as the Piscataway intersection as above. This one has no green arrow. Sorry it's only a GSV link, when I went by it was raining and missed the portion of it actually flashing.

fwydriver405

#1955
Fixed the quoting in the original post...

Quote from: jakeroot on March 25, 2022, 03:10:44 AM
Quote from: fwydriver405 on March 24, 2022, 10:55:59 PM
Quote from: jakeroot on March 24, 2022, 10:38:45 PM
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.

If you are implying that every intersection with a dedicated left turn lane should have, at the very least, a permissive-only FYA, I feel like that may be a bit overkill. There are plenty of intersections where there is no need for any protected phasing. In those cases, yes, a permissive-only FYA wouldn't hurt. But I also don't think it's strictly necessary.

I only mention that, as MaineDOT is requring new installs to have FYA's if there is a dedicated single left turn lane only crossing one opposing thru lane with either permissive-only or permissive-protected phasing. However, even with this requirement, I have seen some new permissive only lefts with dedicated left turn lanes with just the green ball and/or permissive-protected lefts with 5-section shared signals - but it is possible those projects may have been approved before the requirement, or it was just signal heads they were replacing and not the controller (which may or may not be able to support FYA overlaps).




Quote from: jeffandnicole on March 25, 2022, 08:29:40 AM
Quote from: fwydriver405 on March 24, 2022, 10:55:59 PM...since the left turns are not on the same rings under the old system which can cause yellow trap.

Yellow traps are caused when the opposing direction has an extended green, which occurs quite rarely.

Even intersections with FLAs often have cross traffic with traditional RYG lights.

Yellow traps are common in Maine (with shared yield on green PPLT signals), but mostly becuase of phase skip being allowed at these intersections. Even intersections with single direction protected only left turns (phase skip lead or single lag) also have this issue occasionally (example).

I know in New Hampshire, even when FYA's are installed on the main road, they sometimes keep the traditional RYG lights for cross traffic for the permissive lefts. As most NHDOT controllers cabinets are still on TS1 (edit, most controllers are of the newer TS2 or ATC spec), it's possible there aren't any more loadswitch spaces available, no more overlaps available, or in some cases, the mast arm can't support an additional signal.

cl94

So, I was poking around San Diego County on GSV and I found an FYA on a local street in El Cajon. California and New Hampshire are the land of "protected lefts only, no exceptions", so this was a bit of a surprise to see. There can't be many protected/permissive signals in California.
Please note: All posts represent my personal opinions and do not represent those of my employer or any of its partner agencies.

Travel Mapping (updated weekly)

jakeroot

Quote from: cl94 on May 21, 2022, 07:01:22 PM
So, I was poking around San Diego County on GSV and I found an FYA on a local street in El Cajon. California and New Hampshire are the land of "protected lefts only, no exceptions", so this was a bit of a surprise to see. There can't be many protected/permissive signals in California.

That whole stretch of roadway is full of them. Certainly one of only a handful of such stretches in California. If I'm honest, the only worrying thing is that they were all installed ten-ish years ago, and there doesn't seem to be much progress in terms of converting other lefts in the area to FYA operations in the period since.

I'd reckon that about 75 to 85 per cent of protected/permissive signals in California are in Los Angeles County.

mrsman

Quote from: jakeroot on May 21, 2022, 07:25:58 PM
Quote from: cl94 on May 21, 2022, 07:01:22 PM
So, I was poking around San Diego County on GSV and I found an FYA on a local street in El Cajon. California and New Hampshire are the land of "protected lefts only, no exceptions", so this was a bit of a surprise to see. There can't be many protected/permissive signals in California.

That whole stretch of roadway is full of them. Certainly one of only a handful of such stretches in California. If I'm honest, the only worrying thing is that they were all installed ten-ish years ago, and there doesn't seem to be much progress in terms of converting other lefts in the area to FYA operations in the period since.

I'd reckon that about 75 to 85 per cent of protected/permissive signals in California are in Los Angeles County.

Anecdotally, I think you are right.  CA is very much known as requiring protected lefts all over the place, even in fairly rural areas.  I don't believe there are any set rules on this similar to what Maine has, but the vast number of protected lefts must at least correspond to a policy if not a formal rule.

Firstly, it has to be kept in mind that Caltrans districts are really their own feifdoms.  Very different policies in each of the several districts.  So it seems that many of the non-urban districts follow the policy of protected lefts for new installations and protected lefts where there is a dedicated left turn lane that is turning against more than one lane of traffic.  Policy over Caltrans roads (i.e. numbered highways) but generally followed in unincorporated counties and even many smaller cities that have independent DOTs.

In the more urban areas like SF, Sac, LA, Orange County, San Diego, you definitely see Caltrans policy being followed carefully in most of the suburban areas, but rarely in the cities.  And each individual city can do what they want.

So let's take El Cajon as it is the example linked above.  From the 1980's until recently most signals seemed to follow the Caltrans policy, protected only lefts across multiple lanes and no protection at all across single lanes.  But more recently, they converted those protected only lefts to PPLTs with the 4 aspect FYA signal.  (This should be straightforward, just add a flashing yellow arrow between yellow arrow and green arrow.)  And it would seem that many other places could do the same thing, since the FYA or other PPLT doesn't violate any rule, even if it does violate the policy in spirit.  But signals that are controlled by Caltrans directly (and probably many existing signals in unincorporated areas) will not be adjusted and will continue to follow the policy.

The only indication of formal policy that I found is at the following link:

https://dot.ca.gov/-/media/dot-media/programs/traffic-operations/documents/mobility/traffic-signal-operatons-manual-1-31-2020-a11y.pdf

Quote

Certain situations exist where safety considerations generally precluded the use of permissive left
turns. In these cases, left turns should be restricted to the exclusive left turn phases. Such situations
include:
• Intersection approaches where crash experience or traffic conflicts criteria are used as the basis for
installing separate left turn phasing.
• Blind intersections where the horizontal or vertical alignment of the road does not allow the left
turning driver adequate sight distance to judge whether or not a gap in on-coming traffic is long
enough to more safely complete his turn.
• High-speed and/or multilane approaches may make it difficult for left turning drivers to judge gaps
in oncoming traffic. Such locations should be evaluated on an individual basis.
• Unusual geometric or traffic conditions may complicate the driver’s task and necessitate the
prohibition of permissive left turns. An example of such conditions is an approach where dual left
turns are provided.
• When normal lead-lag phasing is used (due to left turn trapping).

Some of the issues noted above that preclude the use of permissive left turns may only be applicable
during certain times of the day. Traditionally, this would require protected only operation for the
entire day.
(Emphasis added)  The use of the FYA display (see section G-3) would allow the indication to operate as
protected only during some times of the day and permissive or protected/permissive during others.
The use of the FYA display can also eliminate the left turn trapping problem that is discussed in the
next section.


The sections that discuss protected left turns seem very standard.  But I think the approach in Caltrans reads the bulleted standards very strictly.  So they basically find nearly every multilane situation as causing difficulty to find a left turn gaps, so they use protected only lefts.  At least the FYA signals will allow some leeway where it is clear that there are certain times of day when the protection is clearly not needed, even if it is presumed to be needed at the busiest times.

Caps81943


jakeroot

Quote from: Caps81943 on June 22, 2022, 08:48:02 PM
https://www.google.com/maps/@37.7778252,-79.9750562,3a,62.7y,261.84h,90.39t/data=!3m6!1e1!3m4!1sKz0f-wHZq0llNEW27iHjEQ!2e0!7i16384!8i8192

I don't think this is how you should use a 3-section FYA...what even is the point of the light then?

It may be bimodal, with a shared green and yellow bottom lens.

Alternatively, it may have been necessary to use the flashing yellow arrow because it was the best way to make it permissive. I think solid green orbs directly over left turn lanes are no longer allowed.

kphoger

Quote from: jakeroot on June 22, 2022, 09:00:30 PM

Quote from: Caps81943 on June 22, 2022, 08:48:02 PM
https://www.google.com/maps/@37.7778252,-79.9750562,3a,62.7y,261.84h,90.39t/data=!3m6!1e1!3m4!1sKz0f-wHZq0llNEW27iHjEQ!2e0!7i16384!8i8192

I don't think this is how you should use a 3-section FYA...what even is the point of the light then?

It may be bimodal, with a shared green and yellow bottom lens.

Alternatively, it may have been necessary to use the flashing yellow arrow because it was the best way to make it permissive. I think solid green orbs directly over left turn lanes are no longer allowed.

I don't see the problem with it to begin with.  Seems like a perfect application to me.
Keep right except to pass.  Yes.  You.
Visit scenic Orleans County, NY!
Male pronouns, please.

Quote from: Philip K. DickIf you can control the meaning of words, you can control the people who must use them.

Caps81943

Quote from: kphoger on June 23, 2022, 09:31:31 AM
Quote from: jakeroot on June 22, 2022, 09:00:30 PM

Quote from: Caps81943 on June 22, 2022, 08:48:02 PM
https://www.google.com/maps/@37.7778252,-79.9750562,3a,62.7y,261.84h,90.39t/data=!3m6!1e1!3m4!1sKz0f-wHZq0llNEW27iHjEQ!2e0!7i16384!8i8192

I don't think this is how you should use a 3-section FYA...what even is the point of the light then?

It may be bimodal, with a shared green and yellow bottom lens.

Alternatively, it may have been necessary to use the flashing yellow arrow because it was the best way to make it permissive. I think solid green orbs directly over left turn lanes are no longer allowed.

I don't see the problem with it to begin with.  Seems like a perfect application to me.

My big issue is that there (seems to be, barring bimodal) no protected phase, making a light here completely unnecessary because there is never any reason to turn opposing traffic red (to allow left turning traffic a protected green), which is the only movement in these continuous green setups.

jakeroot

Quote from: Caps81943 on June 23, 2022, 12:00:56 PM
Quote from: kphoger on June 23, 2022, 09:31:31 AM
Quote from: jakeroot on June 22, 2022, 09:00:30 PM

Quote from: Caps81943 on June 22, 2022, 08:48:02 PM
https://www.google.com/maps/@37.7778252,-79.9750562,3a,62.7y,261.84h,90.39t/data=!3m6!1e1!3m4!1sKz0f-wHZq0llNEW27iHjEQ!2e0!7i16384!8i8192

I don't think this is how you should use a 3-section FYA...what even is the point of the light then?

It may be bimodal, with a shared green and yellow bottom lens.

Alternatively, it may have been necessary to use the flashing yellow arrow because it was the best way to make it permissive. I think solid green orbs directly over left turn lanes are no longer allowed.

I don't see the problem with it to begin with.  Seems like a perfect application to me.

My big issue is that there (seems to be, barring bimodal) no protected phase, making a light here completely unnecessary because there is never any reason to turn opposing traffic red (to allow left turning traffic a protected green), which is the only movement in these continuous green setups.

If it does only operate in permissive mode (no bimodal lens), then yes, they could have probably remove the whole signal. Still, my guess is that they retrofitted the existing left turn signal with a bimodal green/yellow lens to reduce or eliminate the need to stop oncoming traffic for just one or two cars. But they've maintained the ability to use the green arrow in case of heavy left turning traffic.

kphoger

Quote from: Caps81943 on June 23, 2022, 12:00:56 PM
Quote from: kphoger on June 23, 2022, 09:31:31 AM
Quote from: jakeroot on June 22, 2022, 09:00:30 PM

Quote from: Caps81943 on June 22, 2022, 08:48:02 PM
https://www.google.com/maps/@37.7778252,-79.9750562,3a,62.7y,261.84h,90.39t/data=!3m6!1e1!3m4!1sKz0f-wHZq0llNEW27iHjEQ!2e0!7i16384!8i8192

I don't think this is how you should use a 3-section FYA...what even is the point of the light then?

It may be bimodal, with a shared green and yellow bottom lens.

Alternatively, it may have been necessary to use the flashing yellow arrow because it was the best way to make it permissive. I think solid green orbs directly over left turn lanes are no longer allowed.

I don't see the problem with it to begin with.  Seems like a perfect application to me.

My big issue is that there (seems to be, barring bimodal) no protected phase, making a light here completely unnecessary because there is never any reason to turn opposing traffic red (to allow left turning traffic a protected green), which is the only movement in these continuous green setups.

So the left turn was converted to permissive only when the existing standard RYG was replaced with an FYA?  This would mean the other two aspects of the FYA are never used.
Keep right except to pass.  Yes.  You.
Visit scenic Orleans County, NY!
Male pronouns, please.

Quote from: Philip K. DickIf you can control the meaning of words, you can control the people who must use them.

Caps81943

Quote from: kphoger on June 23, 2022, 12:16:32 PM
Quote from: Caps81943 on June 23, 2022, 12:00:56 PM
Quote from: kphoger on June 23, 2022, 09:31:31 AM
Quote from: jakeroot on June 22, 2022, 09:00:30 PM

Quote from: Caps81943 on June 22, 2022, 08:48:02 PM
https://www.google.com/maps/@37.7778252,-79.9750562,3a,62.7y,261.84h,90.39t/data=!3m6!1e1!3m4!1sKz0f-wHZq0llNEW27iHjEQ!2e0!7i16384!8i8192

I don't think this is how you should use a 3-section FYA...what even is the point of the light then?

It may be bimodal, with a shared green and yellow bottom lens.

Alternatively, it may have been necessary to use the flashing yellow arrow because it was the best way to make it permissive. I think solid green orbs directly over left turn lanes are no longer allowed.

I don't see the problem with it to begin with.  Seems like a perfect application to me.

My big issue is that there (seems to be, barring bimodal) no protected phase, making a light here completely unnecessary because there is never any reason to turn opposing traffic red (to allow left turning traffic a protected green), which is the only movement in these continuous green setups.

So the left turn was converted to permissive only when the existing standard RYG was replaced with an FYA?  This would mean the other two aspects of the FYA are never used.

Correct. Which, to me, just removing the light completely has the exact same effect.

jakeroot

Have you confirmed it's not bimodal? They are quite common, particularly retrofits (as could be the case here).

mrsman

Quote from: jakeroot on June 24, 2022, 01:14:51 AM
Have you confirmed it's not bimodal? They are quite common, particularly retrofits (as could be the case here).

I also presume it's bimodal.  Older GSVs do give an indication of a retrofit, since it appears that the left turn used to be protected only (and the single phase signals on the right used to be green orbs instead of green straight arrows).


plain

If it is bi-modal, it would be the first VDOT-installed bi-modal signal I've ever seen in my life.

Newport News had them at a couple locations (long gone) and Charlottesville still have them all over the city.
Newark born, Richmond bred

Amtrakprod

Quote from: Caps81943 on June 22, 2022, 08:48:02 PM
https://www.google.com/maps/@37.7778252,-79.9750562,3a,62.7y,261.84h,90.39t/data=!3m6!1e1!3m4!1sKz0f-wHZq0llNEW27iHjEQ!2e0!7i16384!8i8192

I don't think this is how you should use a 3-section FYA...what even is the point of the light then?
You can use them to delay turns to protect pedestrians, improve yielding conditions, and prevent the yellow trap.


iPhone
Roadgeek, railfan, and crossing signal fan. From Massachusetts, and in high school. Youtube is my website link. Loves FYAs signals. Interest in Bicycle Infrastructure. Owns one Leotech Pedestrian Signal, and a Safetran Type 1 E bell.

mrsman

Quote from: plain on June 24, 2022, 01:21:06 PM
If it is bi-modal, it would be the first VDOT-installed bi-modal signal I've ever seen in my life.

Newport News had them at a couple locations (long gone) and Charlottesville still have them all over the city.

Clicking on the link shows a yellow arrow illuminated in the bottom aspect.  So that leads us to believe that the top aspect is red arrow and the middle aspect is solid yellow arrow.  It also excludes the possibility that the middle aspect will flash to provide the flashing yellow arrow, since from the picture it is clear that the bottom aspect is a yellow arrow, and implicit that the bottom aspect is flashing.

So while there are certain places with a RA-YA-FYA setup that does not provide for a protected green arrow, that can't be the case here.  And that is because there is a traffic signal in the opposing direction and no traffic signal in the perpendicular direction.  The traffic signal in the opposing direction is R-Y-G, so presumably at some point in the cycle (or when enough cars are waiting in queue at the left turn lane), that signal will turn red.  And when that signal is red, it provides the opportunity for a protected green arrow.

So while I have never been to this intersection, and I understand that bimodal signals are rare for VDOT, I have to conclude that the signal provides for both a green arrow and a flashing yellow arrow in the bottom aspect, logically, based on the above.

[And I also agree that it would be a good idea to replace this with a 4-aspect signal face with FYA for purposes of clarity, but likely wasn't done for budgetary reasons.  I think people should be happy that this protected only left turn was converted to allow permissive left turns by incorporating a FYA.]

MASTERNC

Looks like the bimodal 3 lens FYA might exist in Western New York, judging by this video.  The county already uses bimodal four lens signals for left turns on county roads.

https://www.wgrz.com/article/traffic/more-flashing-yellow-arrows-are-coming-to-wny-nysdot-travel-traffic/71-813690f2-455a-4cf2-adbc-ddba37a246b7

CardInLex

Quote from: MASTERNC on July 11, 2022, 04:41:34 PM
Looks like the bimodal 3 lens FYA might exist in Western New York, judging by this video.  The county already uses bimodal four lens signals for left turns on county roads.

https://www.wgrz.com/article/traffic/more-flashing-yellow-arrows-are-coming-to-wny-nysdot-travel-traffic/71-813690f2-455a-4cf2-adbc-ddba37a246b7

I haven't seen a three section FYA/GA bimodal before. The ones I have seen (in Lexington, KY) are FYA/SYA bimodal, set up like this:

RA
SYA/FYA
GA

roadfro

Quote from: CardInLex on July 11, 2022, 06:50:47 PM
I haven't seen a three section FYA/GA bimodal before. The ones I have seen (in Lexington, KY) are FYA/SYA bimodal, set up like this:

RA
SYA/FYA
GA

I wouldn't consider FYA/SYA "bimodal" in the sense typically used here. A true bimodal would be a single signal aspect that can display different colors, like green and yellow.
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.

jakeroot

Quote from: roadfro on July 12, 2022, 11:53:47 AM
Quote from: CardInLex on July 11, 2022, 06:50:47 PM
I haven't seen a three section FYA/GA bimodal before. The ones I have seen (in Lexington, KY) are FYA/SYA bimodal, set up like this:

RA
SYA/FYA
GA

I wouldn't consider FYA/SYA "bimodal" in the sense typically used here. A true bimodal would be a single signal aspect that can display different colors, like green and yellow.

Perhaps "bi-operational"  would be a better term.



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