One-aspect traffic lights (aka "perpetual green light")

[interstatefan990]

Here's one in Seattle where it even has a yellow and red signal (that is never used).

It's not so in this case, but I wonder if three-aspect signals with unused yellow and red lens could be used instead of a single-aspect green, to prevent possible motorist confusion given the rarity of permanent greens. Almost like a placebo effect.

[kphoger]

It just occurred to me while I was in Mexico several days ago, that these nifty new signals that seem to be popping up all over Mexico only have a single aspect but aren't perpetually green.  That is to say, it's a single aspect for all three phases (or four, considering Mexico uses a flashing green in advance of the amber).  In fact, when I was in town, the post-mounted signal in that GSV shot wasn't working at all, so the approach literally had only one aspect.

[jakeroot]

Ontario doesn't do the above when the ramp is behind the signal, probably for pedestrian reasons?

I think most common would not be using any pedestrian crossing, as it's assumed access to/from either side of the road would be done before or after the interchange, rather than at it.

That said, even at examples with continuous green signals, you could have pedestrian crossings a few hundred feet beyond the signal using regular pedestrian warning signs.

[Hobart]

This is a very basic example but it's from my hometown.

The right turn movement from eastbound 179th street to southbound Lagrange Road (US-45) in Tinley Park has a channelized right turn lane setup which merges onto LaGrange in the form of an extra lane. This isn't too rare in IDOT's practices, but it isn't an everyday thing either.

https://www.google.com/maps/@41.5648572,-87.8522782,3a,75y,107.18h,83.86t/data=!3m6!1e1!3m4!1sEqIKc3HPGCJ0UqYgH9wRxA!2e0!7i16384!8i8192

[Bruce]

A variant seen on Kingsway in Vancouver: top ball is perpetual green, bottom is a left turn arrow.

[amroad17]

KY 237 Hebron, KY...
https://goo.gl/maps/KEo66Y7DTT2wmfAGA

[jtespi]

It just occurred to me while I was in Mexico several days ago, that these nifty new signals that seem to be popping up all over Mexico only have a single aspect but aren't perpetually green.  That is to say, it's a single aspect for all three phases (or four, considering Mexico uses a flashing green in advance of the amber).  In fact, when I was in town, the post-mounted signal in that GSV shot wasn't working at all, so the approach literally had only one aspect.

Wow, those are really cool LED traffic signals with embedded words. The green signal displaying "siga" means to continue (moving). I guess they used that word instead of "vamos," which would be a more literal translation from English "go" but 5 letters long instead of 4.

Are there any other threads about these unique traffic signals in Mexico? I'd like to read more about those.

[amroad17]

^ Check out the ALTO one on the opposite signal to the one shown!

[jakeroot]

A variant seen on Kingsway in Vancouver: top ball is perpetual green, bottom is a left turn arrow.

Another one of these downtown on Georgia at Pender:

https://youtu.be/6-K46IWuHoQ

[mrsman]

I wonder how some of these more unique single aspect lights work are interpreted by the color blind.  To my understanding, many who are color blind can legally operate vehicles, even if they have red/green color blindness, because they judge the signal based on the position of the signal.  Top light = stop, bottom light = go.  (I am not sure if they can judge position as well at night.)

Now proper implementation of MUTCD means that you can never have a red straight arrow.  So a lone green straight arrow, which is the most frequently used form of single aspect signal should be OK.  But the lone green balls, and especially the examples that jakeroot posted from BC where the green ball sits on top of the green arrow must be especially confusing for the color blind.  The top light is green, instead of red.

[steviep24]

Perpetual green arrows on NY 104 at Ridgeway Ave. in Rochester, NY

https://www.google.com/maps/@43.194388,-77.6273647,3a,37.5y,268.95h,94.92t/data=!3m6!1e1!3m4!1snqarZg9ENsiW4yqqeHpMFA!2e0!7i16384!8i8192?hl=en

These were posted in the Eternal Green Light thread.

[PurdueBill]

A variant seen on Kingsway in Vancouver: top ball is perpetual green, bottom is a left turn arrow.

Another one of these downtown on Georgia at Pender:

The top green reminds me of this beauty that they had captured on the old MassRoads.com (in 2001!) which fortunately I had saved because they were so great...a signal in Billerica, Mass was once set up this way.





Also, the thru movements to the right of the crazy left turn had single-aspect heads.


The one copy of the page with the images (mostly) showing is at http://web.archive.org/web/20030606214927/http://massroads.com:80/billerica_left_turn.shtml but I am glad I saved the pics (in 2006, according to my computer) just in case because not all archived copies seem to bring up the pics of this nutty signal with green on top.

You can see on street view that by 2008, the signal was compliant with green balls for the oncoming traffic and a doghouse for the left turns.  It really is a good candidate for a FYA.

[bzakharin]

I don't think NJ has any true examples. I've seen flashing yellow and red lights at an intersection reinforcing the stop signs, but those aren't true traffic lights.  https://www.google.com/maps/@39.531376,-75.1071113,3a,75y,275.47h,87.98t/data=!3m6!1e1!3m4!1sLvCJRCgy2jRUvFE34mx2lQ!2e0!7i16384!8i8192!5m1!1e1
There is also an intersection with a permanent red, but it has a regular traffic light where the red is always on and the green ball replaced with a green left arrow.
https://www.google.com/maps/@39.9371042,-74.9699042,3a,75y,33.71h,84.61t/data=!3m7!1e1!3m5!1swwKmJ-q6nX2Ue9p52UGTqg!2e0!5s20160901T000000!7i13312!8i6656!5m1!1e1

[rickmastfan67]

PurdueBill, just an FYI, but Facebook image links don't work 95% of the time.  Might want to upload to imgur instead when posting to the forum.

[PurdueBill]

PurdueBill, just an FYI, but Facebook image links don't work 95% of the time.  Might want to upload to imgur instead when posting to the forum.

That wasn't where I thought they were coming from in the first place...hmm.  Bet I was in the wrong window again.  Trying editing...

[rickmastfan67]

PurdueBill, just an FYI, but Facebook image links don't work 95% of the time.  Might want to upload to imgur instead when posting to the forum.

That wasn't where I thought they were coming from in the first place...hmm.  Bet I was in the wrong window again.  Trying editing...

Working now.

[webny99]

OK, I just stumbled upon a really interesting example near Charleston, WV. I've never seen anything quite like it: the right lane has a permanent green arrow, while the left lane functions as part of the intersection with the traditional green-yellow-red. I'm not sure why anyone would ever use the left lane if the light was red. It could make sense to use the left lane for passing during the green phase, but you still run the risk of it turning yellow/red while the right lane keeps moving.

Another possible argument for using the left lane would be to turn left at the next intersection. But even setting aside the fact that there's plenty of time to merge, note the ramp off to the right: That ramp is a flyover of the next intersection, so there would be no reason to be going straight here and then turning left when you could just use the flyover instead. A fascinating case study all around.

[andrepoiy]

OK, I just stumbled upon a really interesting example near Charleston, WV. I've never seen anything quite like it: the right lane has a permanent green arrow, while the left lane functions as part of the intersection with the traditional green-yellow-red. I'm not sure why anyone would ever use the left lane if the light was red. It could make sense to use the left lane for passing during the green phase, but you still run the risk of it turning yellow/red while the right lane keeps moving.

Another possible argument for using the left lane would be to turn left at the next intersection. But even setting aside the fact that there's plenty of time to merge, note the ramp off to the right: That ramp is a flyover of the next intersection, so there would be no reason to be going straight here and then turning left when you could just use the flyover instead. A fascinating case study all around.

That's interesting. It would be nice to know the logic of the traffic engineer who designed this

[vdeane]

OK, I just stumbled upon a really interesting example near Charleston, WV. I've never seen anything quite like it: the right lane has a permanent green arrow, while the left lane functions as part of the intersection with the traditional green-yellow-red. I'm not sure why anyone would ever use the left lane if the light was red. It could make sense to use the left lane for passing during the green phase, but you still run the risk of it turning yellow/red while the right lane keeps moving.

Another possible argument for using the left lane would be to turn left at the next intersection. But even setting aside the fact that there's plenty of time to merge, note the ramp off to the right: That ramp is a flyover of the next intersection, so there would be no reason to be going straight here and then turning left when you could just use the flyover instead. A fascinating case study all around.

I noticed what looks like an extra point to attach a signal head on the span wire... is it possible that this used to just be a straight signal and traffic started to outgrow it, so placing those dividers and adding the perpetual green on the right lane was a retrofit?

[Dirt Roads]

OK, I just stumbled upon a really interesting example near Charleston, WV. I've never seen anything quite like it: the right lane has a permanent green arrow, while the left lane functions as part of the intersection with the traditional green-yellow-red. I'm not sure why anyone would ever use the left lane if the light was red. It could make sense to use the left lane for passing during the green phase, but you still run the risk of it turning yellow/red while the right lane keeps moving.

Another possible argument for using the left lane would be to turn left at the next intersection. But even setting aside the fact that there's plenty of time to merge, note the ramp off to the right: That ramp is a flyover of the next intersection, so there would be no reason to be going straight here and then turning left when you could just use the flyover instead. A fascinating case study all around.

That's interesting. It would be nice to know the logic of the traffic engineer who designed this

The answer is already upstream in this thread:  https://www.aaroads.com/forum/index.php?action=post;quote=2709015;topic=31021.0

Might as well repost it:

These were common in Charleston, West Virginia back in the 1960s and 1970s.  Both the upriver lanes of Southside Expressway (southbound WV-61) and Kanawha Boulevard (sometimes Alt US-60, eastbound lanes) were equipped with full signals in the left lane and thru perpetual green signals on the right lanes (with Bots Dots between the lanes) at most of the signalized intersections.  It was funny to see out-of-towners pass on the left only to get snagged by the traffic signal, whereas locals just doodled in the right lane but kept moving.  There were so many in a row on The Boulevard that during rush hour, it effectively created a single lane eastbound with a dedicated turn lane.  By the mid-1970s, so many businesses were moving out of the West End that there was hardly any need for left turns off the Boulevard during the morning rush hour.

[webny99]

The answer is already upstream in this thread:  https://www.aaroads.com/forum/index.php?action=post;quote=2709015;topic=31021.0

Might as well repost it:

These were common in Charleston, West Virginia back in the 1960s and 1970s.  Both the upriver lanes of Southside Expressway (southbound WV-61) and Kanawha Boulevard (sometimes Alt US-60, eastbound lanes) were equipped with full signals in the left lane and thru perpetual green signals on the right lanes (with Bots Dots between the lanes) at most of the signalized intersections.  It was funny to see out-of-towners pass on the left only to get snagged by the traffic signal, whereas locals just doodled in the right lane but kept moving.  There were so many in a row on The Boulevard that during rush hour, it effectively created a single lane eastbound with a dedicated turn lane.  By the mid-1970s, so many businesses were moving out of the West End that there was hardly any need for left turns off the Boulevard during the morning rush hour.

Interesting. I thought of this thread when I came across this example, but must have missed this before. I'm envisioning that I would probably risk trying to use the left lane if it had a lot less traffic, but it would depend on the signal timing. It's also interesting because it could potentially allow more favorable green phases for the side street since one direction always keeps moving.

[Quillz]

One just got installed right by LAX. Sepulveda/92nd now has a signal light, but only the southbound lanes on Sepulveda interact with 92nd. The northbound lanes have a perpetual green, although it's a typical signal light, not a single bulb. However, it did break down not too long ago so I did have to stop there once since it was flashing red.

[Dirt Roads]

These were common in Charleston, West Virginia back in the 1960s and 1970s.  Both the upriver lanes of Southside Expressway (southbound WV-61) and Kanawha Boulevard (sometimes Alt US-60, eastbound lanes) were equipped with full signals in the left lane and thru perpetual green signals on the right lanes (with Bots Dots between the lanes) at most of the signalized intersections.  It was funny to see out-of-towners pass on the left only to get snagged by the traffic signal, whereas locals just doodled in the right lane but kept moving.  There were so many in a row on The Boulevard that during rush hour, it effectively created a single lane eastbound with a dedicated turn lane.  By the mid-1970s, so many businesses were moving out of the West End that there was hardly any need for left turns off the Boulevard during the morning rush hour.

Interesting. I thought of this thread when I came across this example, but must have missed this before. I'm envisioning that I would probably risk trying to use the left lane if it had a lot less traffic, but it would depend on the signal timing. It's also interesting because it could potentially allow more favorable green phases for the side street since one direction always keeps moving.

None of the ones on eastbound Kanawha Boulevard remain (most of the Boulevard has been converted to two lanes with a left turn lane at the eastbound signalized intersections). 

Only one remains on southbound MacCorkle Avenue at the MoHarv entrance (now the University of Charleston):
https://www.google.com/maps/@38.3316361,-81.6163145,3a,38.8y,108.34h,85.67t/data=!3m6!1e1!3m4!1sVyDMzqvICLmOaPLFmB1FbA!2e0!7i16384!8i8192

I also posted a detailed listing of the original locations in a Bots Dots thread some time ago. It mentioned another location on the Southside Expressway (MacCorkle Avenue) in the northbound direction.  It's still there, and it is very close to the one in your post coming off of Corridor G.  It was the only one that was northbound along the river:
https://www.google.com/maps/@38.3501751,-81.6426911,3a,15.1y,308.79h,90.7t/data=!3m6!1e1!3m4!1sAIekyQ2npfOBb1Gpy8SGDQ!2e0!7i16384!8i8192

All of these had Bots Dots until sometime in the 1990s.

[Bitmapped]

These were common in Charleston, West Virginia back in the 1960s and 1970s.  Both the upriver lanes of Southside Expressway (southbound WV-61) and Kanawha Boulevard (sometimes Alt US-60, eastbound lanes) were equipped with full signals in the left lane and thru perpetual green signals on the right lanes (with Bots Dots between the lanes) at most of the signalized intersections.  It was funny to see out-of-towners pass on the left only to get snagged by the traffic signal, whereas locals just doodled in the right lane but kept moving.  There were so many in a row on The Boulevard that during rush hour, it effectively created a single lane eastbound with a dedicated turn lane.  By the mid-1970s, so many businesses were moving out of the West End that there was hardly any need for left turns off the Boulevard during the morning rush hour.

Interesting. I thought of this thread when I came across this example, but must have missed this before. I'm envisioning that I would probably risk trying to use the left lane if it had a lot less traffic, but it would depend on the signal timing. It's also interesting because it could potentially allow more favorable green phases for the side street since one direction always keeps moving.

None of the ones on eastbound Kanawha Boulevard remain (most of the Boulevard has been converted to two lanes with a left turn lane at the eastbound signalized intersections). 

Only one remains on southbound MacCorkle Avenue at the MoHarv entrance (now the University of Charleston):
https://www.google.com/maps/@38.3316361,-81.6163145,3a,38.8y,108.34h,85.67t/data=!3m6!1e1!3m4!1sVyDMzqvICLmOaPLFmB1FbA!2e0!7i16384!8i8192

I also posted a detailed listing of the original locations in a Bots Dots thread some time ago. It mentioned another location on the Southside Expressway (MacCorkle Avenue) in the northbound direction.  It's still there, and it is very close to the one in your post coming off of Corridor G.  It was the only one that was northbound along the river:
https://www.google.com/maps/@38.3501751,-81.6426911,3a,15.1y,308.79h,90.7t/data=!3m6!1e1!3m4!1sAIekyQ2npfOBb1Gpy8SGDQ!2e0!7i16384!8i8192

All of these had Bots Dots until sometime in the 1990s.

This sort of setup isn't all that rare in WV. There are three currently in the Morgantown area and had been a fourth until its associated intersection gained a fourth leg. One of the intersections, WV 7 at the I-68 westbound ramps, has no signal-controlled through lane for WV 7 eastbound traffic: https://goo.gl/maps/45KzLxVEA39vyj6s8

The intersections are good for keeping traffic flowing. They don't work where pedestrians might be crossing the road, which is why the examples along Kanawha Boulevard through Charleston proper were removed.

The reflector posts are a major upgrade from the Botts Dots, but I still wish WVDOH would do something more solid to separate the continuous through lanes from the signal-controlled ones. The setup can be a bit confusing at first for drivers on the side road not expecting it.

[MASTERNC]

There were a few heading up and down the hill from Charleston Airport the last time I was there.  Most of the bypass lanes were going downhill.

https://goo.gl/maps/as637zYPmJmfVRAq8

Here's another such intersection without the signal (sign in its place) in Richmond, VA

https://goo.gl/maps/9TxhcVPZpE92ZVYbA