Misleading Traffic Signal

Started by webny99, April 10, 2018, 04:16:25 PM

Previous topic - Next topic

roadfro

Quote from: freebrickproductions on April 11, 2018, 11:19:33 PM
Quote from: webny99 on April 11, 2018, 08:59:18 PM
The most sensible solution is still to eliminate the leftmost signal altogether*. I can't think of one reason to justify it even being there, and I'm sure it's substandard (though I don't know what the MUTCD has to say on the issue).
Maybe it should be changed to a three-section (R-Y-Y) Flashing Yellow Arrow?

If the approach is marked as a dedicated left turn lane, then per the 2009 MUTCD, you cannot use a green ball centered over the left turn lane.

Replacing the leftmost signal head with a 3-section permissive-only FYA, or removing the leftmost signal head entirely, would be two easy ways to bring this approach into compliance with MUTCD.


Quote from: jeffandnicole on April 12, 2018, 06:10:16 AM
The MUTCD says one signal per lane, so its existence is very legit.

The MUTCD does *not* require one signal head per lane. The standard is minimum two primary signal heads for the through movement, or two primary signal heads for the major turning movement if there is no through movement on the approach.

However, MUTCD includes guidance for roads with speeds 45mph+ and multiple through lanes. If "N" is the number of through lanes, then it is recommended to have N primary signal heads on the approach and mount N-1 of these overhead, and preferably all primary signal heads overhead when practical. (Table 4D-1 shows this, only taking N to 4 lanes.) So this table seems to prompt many agencies to install one signal per lane on through approaches.
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.


kalvado

Quote from: roadfro on April 14, 2018, 02:07:34 PM
Quote from: freebrickproductions on April 11, 2018, 11:19:33 PM
Quote from: webny99 on April 11, 2018, 08:59:18 PM
The most sensible solution is still to eliminate the leftmost signal altogether*. I can't think of one reason to justify it even being there, and I'm sure it's substandard (though I don't know what the MUTCD has to say on the issue).
Maybe it should be changed to a three-section (R-Y-Y) Flashing Yellow Arrow?

If the approach is marked as a dedicated left turn lane, then per the 2009 MUTCD, you cannot use a green ball centered over the left turn lane.

Replacing the leftmost signal head with a 3-section permissive-only FYA, or removing the leftmost signal head entirely, would be two easy ways to bring this approach into compliance with MUTCD.

Thank you, this is EXACTLY what I think is the source of confusion - green ball centered over a left turn lane. Now we need an quote from MUTCD  to close the issue. 

jakeroot

#27
I think this misunderstanding highlights why some states do not mount permissive green orb signals directly over left turn lanes. Here in Washington, although there are exceptions, doghouses are mounted on/near the line between the left turn lane and the left-most through lane. This is to reduce the chance that a left turner incorrectly presumes the green orb above their lane to mean "protected left". Why exactly scooting the green orb 6 feet to the right makes a world of difference? I don't know for sure, but I've been told that old protected lefts did not use arrows, with "LEFT TURN SIGNAL" signs being used to denote its use. As these were phased out, I guess it was decided that drivers might be misled by green orbs directly above their lane (failing to note the lack of a "LEFT TURN SIGNAL" sign), and would assume the turn was protected. So the best option was to never placed green orbs directly above a left turn lane.

Here in Washington, until the introduction of the FYA, it was common for new mast arms to have more than one plumbizer(?) for a left turn signal: one for a protected, all arrow display, and one for a doghouse. In the photo below, you can see how the far left plumbizer is not in use because the left turn is protective/permissive. The doghouse that was installed instead was placed off to the right on a custom plumbizer specifically for it:


kalvado

Quote from: jakeroot on April 14, 2018, 06:45:54 PM
I think this misunderstanding highlights why some states do not mount permissive green orb signals directly over left turn lanes.
In general I like doghouse configuration since it relays a clear message of green ball being separate from left turn permitted signal. "yield on green" is another way of doing the same. Offsetting signal is a weaker, but still a message.

jakeroot

Quote from: kalvado on April 14, 2018, 06:51:52 PM
Quote from: jakeroot on April 14, 2018, 06:45:54 PM
I think this misunderstanding highlights why some states do not mount permissive green orb signals directly over left turn lanes.

In general I like doghouse configuration since it relays a clear message of green ball being separate from left turn permitted signal. "yield on green" is another way of doing the same. Offsetting signal is a weaker, but still a message.

Right. A doghouse centered over a left turn lane is less likely to be misconstrued than a three-head all orb display. But as a matter of practice, green orbs, be them part of a fully permissive display or protective/permissive display, are usually offset to the right around here, with no difference noted between whether the display is part of a doghouse/tower or not.

webny99

Thanks @roadfro for confirmation regarding the issue in the OP. As I suspected, simple removal of the "left turn only" sign would certainly help, but would not be enough on it's own. One of the two options outlined would still be needed.

Quote from: jakeroot on April 14, 2018, 07:19:26 PM
A doghouse centered over a left turn lane is less likely to be misconstrued than a three-head all orb display.

But at the intersection in question, though, a doghouse would create even more confusion (taking things to a whole new level) because there's no protected phase. Trying to imagine two green balls at the bottom, but yet permissive-only left turns. THAT would be dangerous... yet in theory (and function, really) is no different from how it is now with the separate head.




Now, I'm in Michigan for the weekend, and they have an interesting approach... they use a separate head with a flashing red ball for left turns.

Apparently, this means stop, then yield (makes sense - flashing red ball would have same meaning as it does at a two-way stop). What I don't understand here is why a stop should be required at all. An FYA (or again, complete elimination of the head) would suffice, as far as I can tell.

According to a friend of mine, Michigan doesn't use green arrows... only flashing red ball or a Michigan left. Slightly OT, but not sure if this holds true statewide...

jakeroot

Quote from: webny99 on April 14, 2018, 07:30:23 PM
Quote from: jakeroot on April 14, 2018, 07:19:26 PM
A doghouse centered over a left turn lane is less likely to be misconstrued than a three-head all orb display.

But at the intersection in question, though, a doghouse would create even more confusion (taking things to a whole new level) because there's no protected phase. Trying to imagine two green balls at the bottom, but yet permissive-only left turns. THAT would be dangerous... yet in theory (and function, really) is no different from how it is now with the separate head.

But how would anyone know that there isn't a protected phase, unless they sat there for ten minutes and observed? I'd venture to guess that most people know what the doghouse layout means.

Quote from: webny99 on April 14, 2018, 07:30:23 PM
According to a friend of mine, Michigan doesn't use green arrows... only flashing red ball or a Michigan left. Slightly OT, but not sure if this holds true statewide...

They'd be the only state in the nation to do so. A bit hard to believe, to be honest.

Brandon

Quote from: webny99 on April 14, 2018, 07:30:23 PM
According to a friend of mine, Michigan doesn't use green arrows... only flashing red ball or a Michigan left. Slightly OT, but not sure if this holds true statewide...

Michigan does indeed use green arrows, even with the flashing red ball.  A common configuration, and one I wish would be standard across the country, is to to have permissive phase first, and use the protected phase to clear out the turn lane afterward.

Red ball: https://goo.gl/maps/jYhoSyTisX12
FYA: https://goo.gl/maps/R8tTphJXXfC2 https://goo.gl/maps/TzmPkAhHjWG2
"If you think this has a happy ending, you haven't been paying attention." - Ramsay Bolton

"Symbolic of his struggle against reality." - Reg

vdeane

Quote from: webny99 on April 14, 2018, 07:30:23 PM
Thanks @roadfro for confirmation regarding the issue in the OP. As I suspected, simple removal of the "left turn only" sign would certainly help, but would not be enough on it's own. One of the two options outlined would still be needed.
Plus then you'd need to widen the road south of there or take away the right turn lane and replace it with the center lane, since there is only one lane on the other side.
Please note: All comments here represent my own personal opinion and do not reflect the official position of NYSDOT or its affiliates.

roadfro

Quote from: kalvado on April 14, 2018, 04:58:36 PM
Quote from: roadfro on April 14, 2018, 02:07:34 PM
If the approach is marked as a dedicated left turn lane, then per the 2009 MUTCD, you cannot use a green ball centered over the left turn lane.

Replacing the leftmost signal head with a 3-section permissive-only FYA, or removing the leftmost signal head entirely, would be two easy ways to bring this approach into compliance with MUTCD.

Thank you, this is EXACTLY what I think is the source of confusion - green ball centered over a left turn lane. Now we need an quote from MUTCD  to close the issue.

Here you go, via https://mutcd.fhwa.dot.gov/htm/2009r1r2/part4/part4d.htm#section4D18
Quote from: 2009 MUTCD
Section 4D.18 Signal Indications for Permissive Only Mode Left-Turn Movements

Standard:
<...>
02 If a separate left-turn signal face is being operated in a permissive only left-turns mode, a CIRCULAR GREEN signal indication shall not be used in that face.




Quote from: webny99 on April 14, 2018, 07:30:23 PM
Now, I'm in Michigan for the weekend, and they have an interesting approach... they use a separate head with a flashing red ball for left turns.

Apparently, this means stop, then yield (makes sense - flashing red ball would have same meaning as it does at a two-way stop). What I don't understand here is why a stop should be required at all. An FYA (or again, complete elimination of the head) would suffice, as far as I can tell.

According to a friend of mine, Michigan doesn't use green arrows... only flashing red ball or a Michigan left. Slightly OT, but not sure if this holds true statewide...

Apparently, Michigan's common approach to left turns was to have a signal head containing a circular red, yellow arrow and green arrow (or all circular displays in older implementations). The illuminated "LEFT" sign was frequently deployed to indicate that this signal head was a left turn device–similar to how "LEFT TURN SIGNAL" signs were sometimes used for older left turn signals that used a red ball (instead of a red arrow for whatever reason) to explain why a driver would see more than one circular signal indication on an approach at a time. (It's been mentioned elsewhere on this board that left red arrows were a rarity in Michigan until recently, despite red arrows becoming common across the country 30+ years ago...)

This setup provided a basis for the use of the flashing circular red for permissive left turns. In theory, a full stop is required as part of the permissive movement; according to other conversations I've read on this board and elsewhere, a full stop was the exception rather than the rule.

Since the adoption the 2009 MUTCD, and the provisions for FYAs, I believe this setup is deprecated and no longer used in new Michigan installations.
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.

webny99

Quote from: jakeroot on April 14, 2018, 09:57:22 PM
But how would anyone know that there isn't a protected phase, unless they sat there for ten minutes and observed? I'd venture to guess that most people know what the doghouse layout means.

I'm saying the current setup would not possibly work as a doghouse. If you made a single change (combined the left two signals into a doghouse - but maintaining solid ball instead of arrows) it would be incredibly substandard and dangerous. That's part of the problem with it, at least IMO.

It seems like you may not have known what I meant - but anyways, to answer your question, they'd know there was no protected phase after they had already had an accident and it was too late  :paranoid:

Quote from: vdeane on April 15, 2018, 06:45:39 PM
Quote from: webny99 on April 14, 2018, 07:30:23 PM
Thanks @roadfro for confirmation regarding the issue in the OP. As I suspected, simple removal of the "left turn only" sign would certainly help, but would not be enough on it's own. One of the two options outlined would still be needed.
Plus then you'd need to widen the road south of there or take away the right turn lane and replace it with the center lane, since there is only one lane on the other side.

What do you mean by this?
I can't imagine a circumstance where Shoecraft would need to be widened - it's already four lanes (3 NB, 1 SB) at the intersection - vs the north side which is only three lanes (lacks right turn lane).

vdeane

Quote from: webny99 on April 17, 2018, 09:30:02 AM
Quote from: vdeane on April 15, 2018, 06:45:39 PM
Plus then you'd need to widen the road south of there or take away the right turn lane and replace it with the center lane, since there is only one lane on the other side.

What do you mean by this?
I can't imagine a circumstance where Shoecraft would need to be widened - it's already four lanes (3 NB, 1 SB) at the intersection - vs the north side which is only three lanes (lacks right turn lane).
The light we're talking about in Shoecraft Rd northbound, no?  It has three lanes: left turn only, through, and right turn only.  Hard Rd on the other side only has one lane northbound.  By removing the left turn only sign as was proposed, Shoecraft would then have two through lanes northbound vs. Hard Rd's one lane.  The traffic has to go somewhere.  You can't have two through lanes entering an intersection and only one leaving.  Either the entering side needs to have the extra lane become a turn lane or remove it, or the leaving side needs another lane added.
Please note: All comments here represent my own personal opinion and do not reflect the official position of NYSDOT or its affiliates.

webny99

Quote from: vdeane on April 17, 2018, 12:55:11 PM
Quote from: webny99 on April 17, 2018, 09:30:02 AM
Quote from: vdeane on April 15, 2018, 06:45:39 PM
Plus then you'd need to widen the road south of there or take away the right turn lane and replace it with the center lane, since there is only one lane on the other side.

What do you mean by this?
I can't imagine a circumstance where Shoecraft would need to be widened - it's already four lanes (3 NB, 1 SB) at the intersection - vs the north side which is only three lanes (lacks right turn lane).
The light we're talking about in Shoecraft Rd northbound, no?  It has three lanes: left turn only, through, and right turn only.  Hard Rd on the other side only has one lane northbound.  By removing the left turn only sign as was proposed, Shoecraft would then have two through lanes northbound vs. Hard Rd's one lane.  The traffic has to go somewhere.  You can't have two through lanes entering an intersection and only one leaving.  Either the entering side needs to have the extra lane become a turn lane or remove it, or the leaving side needs another lane added.

Oh!... now I got it. But removing the sign wouldn't require changing the function of the lane... it would just (supposedly) remove the confusion at the signal. The lane would still be a left turn only lane (with pavement markings and such), but without the sign on the mast arm, it would (again, supposedly) be more clear that left turns are permissive only.

That's part of why I said removing that sign wouldn't be enough... it wouldn't really help, as you'd still have a green signal directly facing the left turn lane, but no protected phase. Now, if we're getting into changing the lane into a through lane, that's another issue altogether.

jakeroot

#38
Quote from: webny99 on April 17, 2018, 09:30:02 AM
Quote from: jakeroot on April 14, 2018, 09:57:22 PM
But how would anyone know that there isn't a protected phase, unless they sat there for ten minutes and observed? I'd venture to guess that most people know what the doghouse layout means.

I'm saying the current setup would not possibly work as a doghouse. If you made a single change (combined the left two signals into a doghouse - but maintaining solid ball instead of arrows) it would be incredibly substandard and dangerous. That's part of the problem with it, at least IMO.

It seems like you may not have known what I meant - but anyways, to answer your question, they'd know there was no protected phase after they had already had an accident and it was too late

If you combined the left and center three-orb displays into a doghouse, you'd just have a mast arm with two overhead doghouses. That's not at all unusual:



Even if they just replaced the left-most three-orb display with a doghouse, drivers would be a lot less likely to miscontrue the signal to mean protected because doghouses have never been used in this manner (except on very rare occasions, and unlike standard three-orb displays). Doghouses are laid out the way they are because they facilitate both protected and permissive movements. On the other hand, apparently, protected signals formerly used nothing more than a "LEFT TURN SIGNAL" sign, so drivers who are old could conceivably misinterpret a standard three-orb display that was situated directly over a left turn lane (a sort of signal-per-lane strategy) as a protected left (your original concern).




For what it's worth, two identical setups to the OP exist near me (one approach lane for each movement). The only difference between the two examples near me and what I see in the OP are the use of "LEFT TURN MUST YIELD" signs.

Fife, WA: https://goo.gl/38Vb7B
South Hill, WA: https://goo.gl/n1pmWN

The Fife example:



Most setups like this in my area would not use a display over the left turn lane (keeping the plumbizer unused until necessary), but things still work because of the sign. Plus the fact that there's no arrows being used.

Brandon

Quote from: webny99 on April 17, 2018, 01:44:52 PM
Quote from: vdeane on April 17, 2018, 12:55:11 PM
Quote from: webny99 on April 17, 2018, 09:30:02 AM
Quote from: vdeane on April 15, 2018, 06:45:39 PM
Plus then you'd need to widen the road south of there or take away the right turn lane and replace it with the center lane, since there is only one lane on the other side.

What do you mean by this?
I can't imagine a circumstance where Shoecraft would need to be widened - it's already four lanes (3 NB, 1 SB) at the intersection - vs the north side which is only three lanes (lacks right turn lane).
The light we're talking about in Shoecraft Rd northbound, no?  It has three lanes: left turn only, through, and right turn only.  Hard Rd on the other side only has one lane northbound.  By removing the left turn only sign as was proposed, Shoecraft would then have two through lanes northbound vs. Hard Rd's one lane.  The traffic has to go somewhere.  You can't have two through lanes entering an intersection and only one leaving.  Either the entering side needs to have the extra lane become a turn lane or remove it, or the leaving side needs another lane added.

Oh!... now I got it. But removing the sign wouldn't require changing the function of the lane... it would just (supposedly) remove the confusion at the signal. The lane would still be a left turn only lane (with pavement markings and such), but without the sign on the mast arm, it would (again, supposedly) be more clear that left turns are permissive only.

That's part of why I said removing that sign wouldn't be enough... it wouldn't really help, as you'd still have a green signal directly facing the left turn lane, but no protected phase. Now, if we're getting into changing the lane into a through lane, that's another issue altogether.

How would there be confusion?  At the similar one I showed you in Plainfield, IL (Lockport Street and IL-59), no one is confused by it at all.  This is much ado about jack shit.
"If you think this has a happy ending, you haven't been paying attention." - Ramsay Bolton

"Symbolic of his struggle against reality." - Reg

roadfro

Quote from: jakeroot on April 17, 2018, 04:42:58 PM
Most setups like this in my area would not use a display over the left turn lane (keeping the plumbizer unused until necessary), but things still work because of the sign. Plus the fact that there's no arrows being used.

Signal terminology note for you, jakeroot:

A "Plumbizer" is the piece that is inserted between different sections of the signal head that projects back to connect the signal head to the mast arm. It is part of (or added to) the signal head.

A "Tenon" (incorrectly called a plumbizer in this quote) is the piece protruding from the mast arm where a signal head is attached.
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.

webny99

Quote from: Brandon on April 17, 2018, 08:42:18 PM
How would there be confusion?  At the similar one I showed you in Plainfield, IL (Lockport Street and IL-59), no one is confused by it at all.  This is much ado about jack shit.

The one you showed me (1) does not have a third signal head directly facing the left lane, and (2) does not have a "left turn only" sign between the left and center signal heads (because, refer to (1), there is no left signal head to begin with, at least not on the mast arm  :pan:). Those are the differences between "acceptable" and "substandard".

Obviously, this is a new install, so there's no evidence as to whether or not it's actually functionally problematic. But it's misleading, and also substandard, as we've established above.


jakeroot

Quote from: roadfro on April 18, 2018, 09:57:08 AM
Quote from: jakeroot on April 17, 2018, 04:42:58 PM
Most setups like this in my area would not use a display over the left turn lane (keeping the plumbizer unused until necessary), but things still work because of the sign. Plus the fact that there's no arrows being used.

Signal terminology note for you, jakeroot:

A "Plumbizer" is the piece that is inserted between different sections of the signal head that projects back to connect the signal head to the mast arm. It is part of (or added to) the signal head.

A "Tenon" (incorrectly called a plumbizer in this quote) is the piece protruding from the mast arm where a signal head is attached.

Thank you. I knew I was using the wrong word, and was patiently awaiting someone to correct me. How did I know that would be you... :-D

webny99

#43
Reviving this nearly four year old thread to give an unexpected update: thanks to an email I sent to NYSDOT yesterday, the issue with this signal head has been resolved!

The slightly longer version of the story: When passing through this intersection yesterday, I was once again bothered by the third green ball, so I decided on a whim to email NYSDOT about it (through their general feedback form online) and see if anything became of it. I left a short description of the problem and a Google Maps link to the signal, and sure enough, I heard back tonight with a very positive update: they acknowledged that the third green ball facing the left lane could be misinterpreted, and that it had been fixed to display red arrow, yellow arrow, and FYA - so basically an acknowledgment that it should have been an FYA all along. And they even sent a picture of each corrected phase! Needless to say, that made my day! I was giddy by the time I finished reading the email. I can't believe I didn't do this sooner!

I've asked permission to share part of the email along with the pictures, so hopefully I can add those here soon! And now I can add "Helped correct an erroneous signal head" to my very short list of notable roadgeek accomplishments! 
:cheers:

mrsman

Quote from: webny99 on February 19, 2022, 01:10:55 AM
Reviving this nearly four year old thread to give an unexpected update: thanks to an email I sent to NYSDOT yesterday, the issue with this signal head has been resolved!

The slightly longer version of the story: When passing through this intersection yesterday, I was once again bothered by the third green ball, so I decided on a whim to email NYSDOT about it (through their general feedback form online) and see if anything became of it. I left a short description of the problem and a Google Maps link to the signal, and sure enough, I heard back tonight with a very positive update: they acknowledged that the third green ball facing the left lane could be misinterpreted, and that it had been fixed to display red arrow, yellow arrow, and FYA - so basically an acknowledgment that it should have been an FYA all along. And they even sent a picture of each corrected phase! Needless to say, that made my day! I was giddy by the time I finished reading the email. I can't believe I didn't do this sooner!

I've asked permission to share part of the email along with the pictures, so hopefully I can add those here soon! And now I can add "Helped correct an erroneous signal head" to my very short list of notable roadgeek accomplishments! 
:cheers:

This is great news!

It's nice to hear these success stories.  I know that I have emailed local DOTs on all sorts of matters and generally only get a form letter response. Even though I am not a traffic engineer, based upon my roadgeeking hobby, I feel that I do have some insight to share and even if I was just a driver driving by, if I were to interpret something incorrectly, that should give them cause for concern.

My most recent reaching out to DOT was to request backplates at an intersection that is particulary hard to see in the early mornings due to sun glare.  This one is particularly bad, because only one of the singal faces has a green arrow, so looking at the other singnal face (which has less glare) wouldn't be helfpul in determining whether it's safe to make a left turn.  The response so far... nothing.

The one success was having the DOT prohbit parking on the street opposite of a small religious facility (RF) in my neigborhood.  The street is very narrow and it is difficult for traffic to go in both directions if cars are parked on both sides of the street.  There is plenty of parking in the neighborhood, but people will park as close as they can to the RF and the street squeezes right there, whereas up the block there is nobody parked at all and it is wide enough.  Because of my intervention and DOT's agreement to sign no parking on one side of the street, now all of the parishioners are only parking on one side of the street and making it easier to pass through.  Every time I pass through when there is an event and there are 10 cars parked on one side and no cars on the other, I feel a little proud at helping the egress in my neighborhood.  A small success, but still a success.



Opinions expressed here on belong solely to the poster and do not represent or reflect the opinions or beliefs of AARoads, its creators and/or associates.