Traffic Signals that turn red that do not need to have the phase

[MCRoads]

Not sure if this is what you are referring to, but the intersection of CO 83 and CO 21 is an incomplete interchange, meant for future expansion. However southbound CO 83 has a traffic signal that sometimes turns red, even though there are no conflicts. (The intersection in question has a left movement only from SB 83.)

[jakeroot]

The main example I was trying to think of before the above post:

This seagull intersection in Puyallup, WA does not need to stop for anything other than when a pedestrian activates the crosswalk, but it goes red when the left turn (from the stem of the T) proceeds anyways:

East Main westbound at Shaw Road

This is the only GSV image I could find showing the red light activated, and it's extremely difficult to tell. This image shows a car waiting while the left turn is still activated (you'll have to click ahead to see that it's not moving), and this image also shows a large backup of waiting traffic resulting from a red light (again, click around to see that they're only just setting off after a red light). None of these street view links show any pedestrians around, so the signal is definitely not programmed correctly.

You're right.  THe whole point of the channelization is to allow the traffic to continue to be green at all times, except for ped crossing.  Given the signilazation as you describe, the channelization serves no function and it might as well be  a regular T intersection.

Here's a video I made yesterday showing the issue in much better detail.

I used the pedestrian crossing to see how things worked with that; the left turn seen in the video remained red despite not having any conflict, and the double right from Shaw Rd having a green right turn arrow. This intersection is definitely not behaving correctly.

https://youtu.be/VQ3ytONBW3g

[mrsman]

The main example I was trying to think of before the above post:

This seagull intersection in Puyallup, WA does not need to stop for anything other than when a pedestrian activates the crosswalk, but it goes red when the left turn (from the stem of the T) proceeds anyways:

East Main westbound at Shaw Road

This is the only GSV image I could find showing the red light activated, and it's extremely difficult to tell. This image shows a car waiting while the left turn is still activated (you'll have to click ahead to see that it's not moving), and this image also shows a large backup of waiting traffic resulting from a red light (again, click around to see that they're only just setting off after a red light). None of these street view links show any pedestrians around, so the signal is definitely not programmed correctly.

You're right.  THe whole point of the channelization is to allow the traffic to continue to be green at all times, except for ped crossing.  Given the signilazation as you describe, the channelization serves no function and it might as well be  a regular T intersection.

Here's a video I made yesterday showing the issue in much better detail.

I used the pedestrian crossing to see how things worked with that; the left turn seen in the video remained red despite not having any conflict, and the double right from Shaw Rd having a green right turn arrow. This intersection is definitely not behaving correctly.

At about 0:25, traffic from Shaw to Main making a left turn seems to be going.  Was this during the pedestrian phase?  If that is the case, then there is a real problem, green left arrow in conflict with a pedestrian walk signal.

[jakeroot]

The main example I was trying to think of before the above post:

This seagull intersection in Puyallup, WA does not need to stop for anything other than when a pedestrian activates the crosswalk, but it goes red when the left turn (from the stem of the T) proceeds anyways:

East Main westbound at Shaw Road

This is the only GSV image I could find showing the red light activated, and it's extremely difficult to tell. This image shows a car waiting while the left turn is still activated (you'll have to click ahead to see that it's not moving), and this image also shows a large backup of waiting traffic resulting from a red light (again, click around to see that they're only just setting off after a red light). None of these street view links show any pedestrians around, so the signal is definitely not programmed correctly.

You're right.  THe whole point of the channelization is to allow the traffic to continue to be green at all times, except for ped crossing.  Given the signilazation as you describe, the channelization serves no function and it might as well be  a regular T intersection.

Here's a video I made yesterday showing the issue in much better detail.

I used the pedestrian crossing to see how things worked with that; the left turn seen in the video remained red despite not having any conflict, and the double right from Shaw Rd having a green right turn arrow. This intersection is definitely not behaving correctly.

At about 0:25, traffic from Shaw to Main making a left turn seems to be going.  Was this during the pedestrian phase?  If that is the case, then there is a real problem, green left arrow in conflict with a pedestrian walk signal.

No, there is no pedestrian phase active during that left turn. When I activated that crosswalk, everything was red except for the right turn from Shaw to Main. Even though the left turn from Main to Shaw does not conflict and could have been green as well.

The signal definitely has some issues as currently setup. More than I realized before I went and checked it out.

[jakeroot]

Another seagull (continuous Green-T) that may as well be a T-intersection given how it operates.

Tukwila, WA: eastbound Southcenter Blvd @ Macadam Road

This one is less interesting than my prior example, since it just uses paint, but I'd argue it's still superior to some other seagulls like this one or this one (both WA) that use continuous-flow signals for the top of the T.

[mrsman]

Another seagull (continuous Green-T) that may as well be a T-intersection given how it operates.

Tukwila, WA: eastbound Southcenter Blvd @ Macadam Road

This one is less interesting than my prior example, since it just uses paint, but I'd argue it's still superior to some other seagulls like this one or this one (both WA) that use continuous-flow signals for the top of the T.

As a matter of safety, if only paint is used to separate left turning from thru traffic, continuous flow should not be done.

I can't speak for the Aberdeen example (as it does appear dangerouse to me), but the Puyallup example does have a small island to channelize the different streams into separate lanes so it is fine and proper as a continuous flow intersection.

[mrsman]

https://www.google.com/maps/@38.8917717,-77.0166112,3a,75y,106.44h,75.54t/data=!3m6!1e1!3m4!1srgmrNdpPzRwnFYFQGTIM-A!2e0!7i16384!8i8192

This is a weird one.  In the original configuration, the thru signals on Penn Ave were always green, as there was no reason for red.

But now, given the median bike lane that is controlled by the thru signals, you need to have it be red so as not to have a conflict between bikes and left turns.  The thru traffic in the thru lanes stop because there is no room to give everyone their own signal.

A careful re-alignment of the signals could avoid the need to have a red signal here, but given its proximity to the Capitol, DC is very sensitive to sightlines and will not allow overhead signals here.  Plus, the median signals have to be removable to accommodate the Inauguration parade.

They just need bike signals and a always green light with a straight arrow.


iPhone

Agreed.  But given the rules on sightlines overhead signals won't be placed here, and I can't imagine how they would get two* green lights with a straight arrow without using an overhead or mast arm signal.

*I believe two are required, just as two are required for most signal indications.  If just one were required, the one on the right could be converted to a green arrow and the one on the left can be a bike signal.

With regards to the signals at Penn/Constitution in Wash DC, as mentioned above, prior to the bike lane installation the signals facing Penn Ave were always green, even though they used standard RYG signals.  There are similar signals on the other side of the Captiol at Penn/Independence.  Always green for straight traffic, even though they use a RYG signal:

https://www.google.com/maps/@38.8872674,-77.0028175,3a,75y,142.76h,74.85t/data=!3m6!1e1!3m4!1swk4pRYT98EC0rlDL4v0wKg!2e0!7i16384!8i8192

[There is a plan by DDOT to put in place bike lanes on this stretch of Penn as well.  As you can see, only two lanes of EB traffic go past this intersection (since the left lane and an option lane force a left onto Independence and then it widens to three lanes.  It should be relatively easy to convert one of those thru lanes into a protected bike lane of some sort.  Whether it will be along the curb or along the median remains to be seen.

https://capitolhillcorner.org/2020/03/06/proposed-bike-lanes-for-pa-avenue-se-will-reduce-travel-lanes-may-affect-parking/
]
 

[jakeroot]

Another seagull (continuous Green-T) that may as well be a T-intersection given how it operates.

Tukwila, WA: eastbound Southcenter Blvd @ Macadam Road

This one is less interesting than my prior example, since it just uses paint, but I'd argue it's still superior to some other seagulls like this one or this one (both WA) that use continuous-flow signals for the top of the T.

As a matter of safety, if only paint is used to separate left turning from thru traffic, continuous flow should not be done.

I can't speak for the Aberdeen example (as it does appear dangerouse to me), but the Puyallup example does have a small island to channelize the different streams into separate lanes so it is fine and proper as a continuous flow intersection.

I think I started to use that Aberdeen example as a "bare minimum" for continuous flow operations; the Tukwila example seemed superior in that the speed limit was lower and the island was properly painted instead of just being a solid line. Still, you're right in that maybe just paint isn't a great idea. Although I wonder why they'd bother painting an island at all if the point wasn't to operate the intersection with continuous flow operations? Just throw up some flexiposts along the island and they'd be done.

My point in bringing up the Puyallup example was actually to highlight an instance where tons of traffic entering from the left has to immediately change to the right, as would be the case at the Tukwila example. The weaving at that Puyallup example is hilarious sometimes (looks like India or Egypt) and I sometimes wonder if a triple left without a continuous flow option might be safer. I don't recall a lot of accidents, but I have a hard time believing they don't happen at all.

[mrsman]

Another seagull (continuous Green-T) that may as well be a T-intersection given how it operates.

Tukwila, WA: eastbound Southcenter Blvd @ Macadam Road

This one is less interesting than my prior example, since it just uses paint, but I'd argue it's still superior to some other seagulls like this one or this one (both WA) that use continuous-flow signals for the top of the T.

As a matter of safety, if only paint is used to separate left turning from thru traffic, continuous flow should not be done.

I can't speak for the Aberdeen example (as it does appear dangerouse to me), but the Puyallup example does have a small island to channelize the different streams into separate lanes so it is fine and proper as a continuous flow intersection.

I think I started to use that Aberdeen example as a "bare minimum" for continuous flow operations; the Tukwila example seemed superior in that the speed limit was lower and the island was properly painted instead of just being a solid line. Still, you're right in that maybe just paint isn't a great idea. Although I wonder why they'd bother painting an island at all if the point wasn't to operate the intersection with continuous flow operations? Just throw up some flexiposts along the island and they'd be done.

My point in bringing up the Puyallup example was actually to highlight an instance where tons of traffic entering from the left has to immediately change to the right, as would be the case at the Tukwila example. The weaving at that Puyallup example is hilarious sometimes (looks like India or Egypt) and I sometimes wonder if a triple left without a continuous flow option might be safer. I don't recall a lot of accidents, but I have a hard time believing they don't happen at all.

I think part of the problem in Puyallup may be that the next signal on the road is not that far away.  The arrangement for continuous flow T-intersections works best when the top of the T is at least a semi-expressway, so that the traffic coming in from the left can merge in a similar manner as a left side freeway entrance.  If the top of the T is more like a normal street with frequent signals, a regular fully signalized intersection would work better.

Here is one on PCH that does this delicately.  The continuous flow intersection is first, then the traffic coming in from the T is stuck in the far left lane and will only be allowed to merge in after the second signal, when merging is easier as the next signal beyond is 3/4 mile away.

https://www.google.com/maps/@34.0283097,-118.5194515,3a,75y,105.59h,83.59t/data=!3m6!1e1!3m4!1st-B4tT8HgXm6zntYOggIVA!2e0!7i16384!8i8192



Your last post brought up a non-signalized intersection.  Non-signalized T intersections should absolutely be designed more like the link showed, because it will allow left turners from the side street to only need to clear one direction of traffic and then can wait in the middle lane to merge safely with the main traffic flow.  One thing that is improtant to realize about the non-signalized variation is that the left turners are fully aware that thru traffic is not stopping for them at all, so there is less of an incentive to make a wide left turn.  At a signalized intersection, one could (wrongfully) assume that if you have a green left arrow, you can turn left and all the cars on the cross street will stop for you and that can lead to dangers which is why the channelization islands are critical for the signalized type.

This intersection here that now appears to be a regular signalized T intersection was once a continuous flow T intersection with a complicated arrangement.

https://www.google.com/maps/@34.1113376,-118.3339135,3a,75y,273.85h,85.87t/data=!3m6!1e1!3m4!1sEksvWXEcIH4coRKCC3A08A!2e0!7i16384!8i8192

It used to be that the 2 lanes NB on Cauhenga were continuous without stopping.  Odin also met the intersection without stopping.  Right lane turned right (south) and left lane turned left.  South of Odin, Cauhenga was 2 NB, 2 SB, and one left turn lane that faced a stop sign.  North of Odin, Cauhenga was 3 NB [1 channelized from Odin, 2 continous], and 1 SB and the SB lane faced a stop sign.  On top of all of that there was an off ramp from the 101 NB that faced a stop sign 1/2 block to the north and allowed a continuous curley-q onto Odin.

Essetially, Cauhenga NB just raced on through.  Odin to NB was continuous, but any traffic that it faced, SB Cauhenga and NB Cauhenga left turn had to stop and yield to the Odin traffic.  right turns were also continuous. 

Why was this done?  The off-ramp led to Highland Ave at the Hollywood Bowl, so most off-ramp traffic took the curly q which was continuous.  A small amount of traffic faced the stop sign to lead to the Ford Ampitheater.  Odin traffic was favored because all trucks from Highland were forced to come this way in order to enter 101 NB from the right side and not enter the freeway into the fast lane (as Highland forces).  Meanwhile, most of the Cauhenga traffic was NB as this roadway becomes one-way NB just past the Ford Ampitheater and the 101 NB ramp.  In reality a very small part of the traffic met stop signs, as most of the traffic was either heading NB on Cauhenga, taking Odin to Cauhenga, or coming off the 101 to Odin to Highland.

The problem was that this was extremely confusing and the current arrangement is far safer.

[STLmapboy]

See CT-9 in Middletown.
Oh New England...

[MASTERNC]

There's one at a shopping center down the street from me.  A two way street becomes a one-way service road, so there is no traffic conflicting with right turns into the shopping center.

https://goo.gl/maps/8jD9P6QbPxeynx198

[mrsman]

There's one at a shopping center down the street from me.  A two way street becomes a one-way service road, so there is no traffic conflicting with right turns into the shopping center.

https://goo.gl/maps/8jD9P6QbPxeynx198

Which signal is unnecessary?  It is true that there are no conflicts with right turns, but thru traffic must get a red light when the shopping center exit gets a green (and right turners get a green arrow).

The problem is the sign "right turn signal".  Leave this as a doghouse and the red signal (timed with the other two signals present here) makes sense.  If they converted the doghouse to RA-YA-GA signal, then you would be correct that the red arrow would be superfluous (unless they wanted a protected pedestrian crossing, but peds are prohibited here and there are no sidewalks).

[jakeroot]

I would guess the redundant red is actually not any red indication, but the lack of a constant-burning green arrow. When the light cycles from green to yellow and then red, there's no reason cars turning right need to stop as there is no conflicting traffic. The doghouse should have a permanent right-turn green arrow.