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Flashing yellow arrow signal heads with three lenses, or four

Started by Tom958, March 13, 2017, 10:39:33 PM

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Tom958

FYA signals with three lenses are becoming increasingly common in the city of Atlanta while, from what I've seen, four-lens heads are prevalent in the suburbs. Hovever, I've been noticing some weirdness lately: at the intersection of Ponce De Leon Avenue and Moreland Avenue/Briarcliff Road, three of the FYA heads have three lenses and only one has four. A mile or so west at Ponce and Boulevard/Monroe, three of the FYA heads have four lenses and only one has three. Those are both in Atlanta and both involve state (and US) routes. Meanwhile, I noticed the other day that the intersection of US 78 and GA 124 way out in Snellville now features one three-lens FYA head and one four--the other two left turns are protected.

Why would three and four-lens heads be mixed like that?  :hmmm:


Big John

The 4-section signals have a solid green arrow at the bottom for a protected phase.

Is that the same for the 3-section signals, or is the bottom section the flashing yellow arrow?  The latter means there is no protected phase but is permitted during the flashing yellow.  If it is the former it looks like preference of putting the solid and flashing yellow in one lens, but not sure why they would be mixed.

Tom958

Quote from: Big John on March 13, 2017, 10:46:24 PM
The 4-section signals have a solid green arrow at the bottom for a protected phase.

Is that the same for the 3-section signals, or is the bottom section the flashing yellow arrow?  The latter means there is no protected phase but is permitted during the flashing yellow.  If it is the former it looks like preference of putting the solid and flashing yellow in one lens, but not sure why they would be mixed.

The bottom lens on the 3 section heads can flash yellow and show solid green.

Big John

This is the first time I heard of a bi-modal FYA/SGA on the same lens on a 3-section signal head. (Approval was given for that on a doghouse signal).  One consideration is there may not be enough vertical clearance for a 4-section head there.  Otherwise it looks like preference of the agency setting up the signals.

Tom958

Clearance is the obvious answer, but I don't see any obvious issues with the installations. On the contrary, the three-lens head in Snellville appears to be on the side with the most clearance.

Ace10

Bimodal FYAs are all over Washington County, Oregon. I think this area was one of the first testing grounds for the new signal, which is why there are so many. One oddity I've noticed in this part of Oregon are that the left turn signals are mounted somewhat lower on the mast arm than the other signals, so this might be why there are so many bimodal signals here.

doorknob60

I don't like the 3 headed ones. In Boise and Meridian, all the ones I can think of are 4 heads, but I think it was Nampa where I saw one or two 3 headed ones pop up (I don't remember). And I've seen them in Oregon (but not when I lived there). I don't like them because you can't immediately tell if the signal is protected only or protected/permissive (which 99% of the time it is if you see a 4 head signal in this case; you obviously can't really tell on a 3 head).

jakeroot

Quote from: Big John on March 13, 2017, 11:11:18 PM
This is the first time I heard of a bi-modal FYA/SGA on the same lens on a 3-section signal head. (Approval was given for that on a doghouse signal).

They've been around for some time. The FYA and SGA share the same lens so the jump from FYA to SYA is more apparent (rather than the same lens going from blinking to solid).

My personal preference is for four-head FYAs, but three-head FYAs are lighter (so better for older mast arms), and can be more easily accommodated without replacing the entire assembly. Pierce County, Washington recently replaced several protected-only turns with three-head FYAs. The only thing they did was swap out the signal housings. Must have been easier than fidgeting with the mast arm mount. Curiously, the middle lens flashes. :-|

jakeroot

Here's a three head flashing yellow arrow in operation. This one is a bit of an oddity, because the flashing yellow arrow shares a lens with the solid yellow arrow. Most three head units share the lens with the solid green arrow:

https://youtu.be/tD7YtZvjTFU

Tom958

So, once again? Any idea why three and four-lens heads would be mixed like that?


Slightly off topic. but today I noticed this: a three-lens FYA head that's almost certainly a dummy, since the left turn is into a tiny commercial parking lot. the yellow light was flashing when the Google car took its shot, but its conceivable that there is no green.

Aerobird

Quote from: Tom958 on March 15, 2017, 12:00:10 AMSlightly off topic. but today I noticed this: a three-lens FYA head that's almost certainly a dummy, since the left turn is into a tiny commercial parking lot. the yellow light was flashing when the Google car took its shot, but its conceivable that there is no green.
Looking at that it also looks a lot like a four-lens FYA that had the bottom (green arrow) lens amputated, so it does seem pretty likely that one's permissive-only.

Edited because a shift of the GSV image showed what I was seeing was just a GSV artifact.
Rule 37. There is no 'overkill'. There is only 'open fire' and 'I need to reload'.

roadfro

Quote from: Big John on March 13, 2017, 11:11:18 PM
This is the first time I heard of a bi-modal FYA/SGA on the same lens on a 3-section signal head. (Approval was given for that on a doghouse signal).

I don't think there's ever been MUTCD approval for a bimodal arrow in a doghouse signal, at least not in the 2009 version or when there was interim approval. (Although I do believe there was some talk of allowing the retrofitting of doghouses to replace the circular indications with appropriate arrow indications, to achieve the FYA effect without new signal housing, in instances where the doghouse could be an exclusive turn signal face–but I imagine it ended up being easier/cheaper to install new FYA heads in these situations instead.)

The bimodal 3-section head (bimodal green arrow/FYA) was introduced simultaneously with the 4-section head in the 2009 MUTCD. The alternate 3-section version, with the solid and flashing yellow in the same section, is a more recent interim approval approved in 2014 that is expected to be adopted in the next version of the MUTCD.
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.

jakeroot

Quote from: roadfro on March 15, 2017, 04:39:13 AM
Quote from: Big John on March 13, 2017, 11:11:18 PM
This is the first time I heard of a bi-modal FYA/SGA on the same lens on a 3-section signal head. (Approval was given for that on a doghouse signal).

I don't think there's ever been MUTCD approval for a bimodal arrow in a doghouse signal, at least not in the 2009 version or when there was interim approval. (Although I do believe there was some talk of allowing the retrofitting of doghouses to replace the circular indications with appropriate arrow indications, to achieve the FYA effect without new signal housing, in instances where the doghouse could be an exclusive turn signal face–but I imagine it ended up being easier/cheaper to install new FYA heads in these situations instead.)

5-section signals with a bi-modal FYA was created for situations where an option lane exists (two lanes each direction with no turn lane). The signal can run with split-phasing during peak times and lead/lag/full permissive during off time. AFAIK, the setup has only been used in Wisconsin and Minnesota.

The FHWA issued an official interpretation several years ago that stated this was an acceptable setup. Our own JMAN123436 (aka JMAN12343610) has several videos on his YouTube page that show this setup in action.

Here's a link to the interpretation: https://goo.gl/insLks

lordsutch

Quote from: Tom958 on March 13, 2017, 10:39:33 PM
FYA signals with three lenses are becoming increasingly common in the city of Atlanta while, from what I've seen, four-lens heads are prevalent in the suburbs. Hovever, I've been noticing some weirdness lately: at the intersection of Ponce De Leon Avenue and Moreland Avenue/Briarcliff Road, three of the FYA heads have three lenses and only one has four. A mile or so west at Ponce and Boulevard/Monroe, three of the FYA heads have four lenses and only one has three. Those are both in Atlanta and both involve state (and US) routes. Meanwhile, I noticed the other day that the intersection of US 78 and GA 124 way out in Snellville now features one three-lens FYA head and one four--the other two left turns are protected.

Why would three and four-lens heads be mixed like that?  :hmmm:

From a research standpoint, it makes sense if it's being used as part of a test to see whether the three-lens signal is as well-understood by drivers as a four-lens signal.

GDOT may also be installing the three-lens signal in cases where the signal is never in protected mode (i.e. only ever does red, solid yellow, and flashing yellow), as a replacement for the green ball. There's an installation in Centerville (at this intersection, but Streetview hasn't been updated) that seems to be configured that way.

JMAN_WiS&S

Here's the link to my playlist of 3 videos. My city actually has two installations, I've filmed both intersections, but the files for the second intersection ended up corrupting before I could upload them. Pardon the shakiness. https://youtu.be/bPGf-sIBgB0?list=PLdFtjnurhUkBbGxF8LkRNlMu8wpil7IA8
Youtube, Twitter, Flickr Username: JMAN.WiS&S
Instagram username: jman.wissotasirens-signals

I am not an official representative or spokesperson for WisDOT. Any views or opinions expressed are purely my own based on my work experiences and do not represent WisDOTs views or opinions.

Mdcastle

Besides inventing the Flashing Yellow Arrow Doghouse, it's notable that Minnesota does not allow three section heads under any circumstances. So far there has not been a permissive only operation but if there was presumably there would be an unused green arrow section at the bottom.

Tom958

Quote from: lordsutch on March 15, 2017, 12:43:30 PMFrom a research standpoint, it makes sense if it's being used as part of a test to see whether the three-lens signal is as well-understood by drivers as a four-lens signal.

Now, how on Earth would one tally the results of such a test?  :hmmm:

To me, it'd make more sense to find two very similar intersections with preexisting protected/permissive lefts on all legs, install three-lens FYA's on one and four-lens FYA's on the other, and wait for some statistically significant results to appear through the noise.

QuoteGDOT may also be installing the three-lens signal in cases where the signal is never in protected mode (i.e. only ever does red, solid yellow, and flashing yellow), as a replacement for the green ball. There's an installation in Centerville (at this intersection, but Streetview hasn't been updated) that seems to be configured that way.

I haven't seen every approach, but I'd be extremely surprised if that was the case since all of the intersections I mentioned have had doghouses in every direction since the earliest Streetviews in 2007. I'm actually starting to come to the conclusion that it's a screwup.

roadfro

Quote from: jakeroot on March 15, 2017, 11:21:53 AM
Quote from: roadfro on March 15, 2017, 04:39:13 AM
Quote from: Big John on March 13, 2017, 11:11:18 PM
This is the first time I heard of a bi-modal FYA/SGA on the same lens on a 3-section signal head. (Approval was given for that on a doghouse signal).

I don't think there's ever been MUTCD approval for a bimodal arrow in a doghouse signal, at least not in the 2009 version or when there was interim approval. (Although I do believe there was some talk of allowing the retrofitting of doghouses to replace the circular indications with appropriate arrow indications, to achieve the FYA effect without new signal housing, in instances where the doghouse could be an exclusive turn signal face–but I imagine it ended up being easier/cheaper to install new FYA heads in these situations instead.)

5-section signals with a bi-modal FYA was created for situations where an option lane exists (two lanes each direction with no turn lane). The signal can run with split-phasing during peak times and lead/lag/full permissive during off time. AFAIK, the setup has only been used in Wisconsin and Minnesota.

The FHWA issued an official interpretation several years ago that stated this was an acceptable setup. Our own JMAN123436 (aka JMAN12343610) has several videos on his YouTube page that show this setup in action.

Here's a link to the interpretation: https://goo.gl/insLks
Well, it's not in the manual, but has been sanctioned by FHWA. I stand corrected. I don't think I've read that interpretation before.
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.

JMAN_WiS&S

Quote from: roadfro on March 20, 2017, 04:24:19 PM
Quote from: jakeroot on March 15, 2017, 11:21:53 AM
Quote from: roadfro on March 15, 2017, 04:39:13 AM
Quote from: Big John on March 13, 2017, 11:11:18 PM
This is the first time I heard of a bi-modal FYA/SGA on the same lens on a 3-section signal head. (Approval was given for that on a doghouse signal).

I don't think there's ever been MUTCD approval for a bimodal arrow in a doghouse signal, at least not in the 2009 version or when there was interim approval. (Although I do believe there was some talk of allowing the retrofitting of doghouses to replace the circular indications with appropriate arrow indications, to achieve the FYA effect without new signal housing, in instances where the doghouse could be an exclusive turn signal face–but I imagine it ended up being easier/cheaper to install new FYA heads in these situations instead.)

5-section signals with a bi-modal FYA was created for situations where an option lane exists (two lanes each direction with no turn lane). The signal can run with split-phasing during peak times and lead/lag/full permissive during off time. AFAIK, the setup has only been used in Wisconsin and Minnesota.

The FHWA issued an official interpretation several years ago that stated this was an acceptable setup. Our own JMAN123436 (aka JMAN12343610) has several videos on his YouTube page that show this setup in action.

Here's a link to the interpretation: https://goo.gl/insLks
Well, it's not in the manual, but has been sanctioned by FHWA. I stand corrected. I don't think I've read that interpretation before.

There's an intersection in Tucson Az that runs 5 stacks with the green ball with the bottom indication being a bimodal green/yellow flashing arrow.
Youtube, Twitter, Flickr Username: JMAN.WiS&S
Instagram username: jman.wissotasirens-signals

I am not an official representative or spokesperson for WisDOT. Any views or opinions expressed are purely my own based on my work experiences and do not represent WisDOTs views or opinions.

jakeroot

Quote from: JMAN12343610 on March 26, 2017, 01:11:19 PM
There's an intersection in Tucson Az that runs 5 stacks with the green ball with the bottom indication being a bimodal green/yellow flashing arrow.

I thought such signals were only found in the upper Midwest. Any idea where this setup is?

JMAN_WiS&S

Quote from: jakeroot on March 26, 2017, 01:53:13 PM
Quote from: JMAN12343610 on March 26, 2017, 01:11:19 PM
There's an intersection in Tucson Az that runs 5 stacks with the green ball with the bottom indication being a bimodal green/yellow flashing arrow.

I thought such signals were only found in the upper Midwest. Any idea where this setup is?
Let me know if this streetview link works. Signals must have been recently replaced as street has become two way. There previously was a 3 section flashing yellow arrow. You can only see current setup from side street as main road Street view is old signals. E Toole Ave

https://goo.gl/maps/YetbBJ9uWiA2

The reason I know this exists is because there is a brief clip in a dashcam video where they make an appearance, and knowing us roadgeeks, of course we'd notice something like that.
Youtube, Twitter, Flickr Username: JMAN.WiS&S
Instagram username: jman.wissotasirens-signals

I am not an official representative or spokesperson for WisDOT. Any views or opinions expressed are purely my own based on my work experiences and do not represent WisDOTs views or opinions.



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