Double left turns with permissive phasing

[kphoger]

That's a lot of people who voted "Cat".

[jakeroot]

I never knew that type of doghouse was used before FYAs for TOD. These posts from different parts of the country are useful. Not everyone has been to/driven in every state nor knows generally what each jurisdiction does/not do.

I guess to a degree its kind of like Dallas phasing*.  You focus on the signal that is in front of you.  If you are in the left turn lane, your signal is the doghouse.  Since the only people looking at the doghouse are turning left, a red arrow makes sense.  But I think for this to work, the red arrow is only on when the adjacent signals have red orbs.  (but not vice versa, you could have green arrow when adjacent signals have red orbs)

* But unlike Dallas phasing it doesn't seem to block the thru signals from view, so these should not be used for lagging lefts because of yellow trap issues.

Correct. The signals are quite like Dallas Phasing, apart from their inability to allow lagging green arrows. During the permissive time of day, they operate exactly like a regular doghouse: activated with adjacent green orb signals, with leading green arrows only. During the protected time of day, the arrows are the only signal faces utilized. There is the red arrow on the top, but this makes no difference to drivers apart from during the protected times of day, when it would be displayed when the adjacent traffic has a green orb displayed.

Honestly, the fact that this kind of display wasn't more common is surprising to me. As far as I know, before the advent of the FYA, it was the only way to allow permissive left turns based on time of day. For most jurisdictions, I suspect that TOD phasing wasn't really important for single left turns; that's fairly evident when you consider that ~99% of Colorado's red arrow doghouses are/were at double left turns, where TOD phasing may actually be important to reduce crashes. Based on this, I think we can assume that Colorado was also an early adopter of double permissive left turns, and one of the first to actually consider how time of day played into crash rates.

[jakeroot]

That's a lot of people who voted "Cat".

Still kind of regret adding it as an option . Only because there are 15 people who voted for neither "yes" or "no".

I never knew that type of doghouse was used before FYAs for TOD. These posts from different parts of the country are useful. Not everyone has been to/driven in every state nor knows generally what each jurisdiction does/not do.

I don't know if this comment was directed at me. My comment around not mentioning those in Colorado is that, for those that are privy to the current double permissive left turn situation, it's already fairly well-known that Colorado has quite a lot of examples. I would have the same reaction if someone posted an example from Tucson; they're so unbelievably common in those jurisdictions, that it's simply not worth pointing out.

Normally, I would say "well, maybe they only saw one", to be a little fairer. But in places like Colorado or Tucson, they aren't really isolated. For example, considering US-89's example from Parker: I don't know how he got to Parker without seeing any others, nor how he left Parker without noticing any additional examples (be them FYA or doghouses). They are literally all over the Denver metro area, and there are multiple other examples in Parker itself (such as here, here, or here -- I found these very quickly).

One exception: if your drive through Colorado was literally all freeway, I can see why you might only see one or two. Still, if you venture a couple miles off any freeway in a relatively suburban or urban area, you should see at least a couple examples.

[jakeroot]

I think I've posted about this before: Japan has literally hundreds, perhaps thousands, of double permissive right turns (they drive on the left). Apart from a couple examples that I might have noted a while back, I haven't posted anymore. Today, I managed to find a triple permissive right turn in Osaka (link and image below).

This marks only the third triple permissive turn I've found (first two in South Africa here and here -- spin camera around to note signal state). Apart from maybe an isolated curb-to-curb turn, I suspect this is not something seen anywhere in North America, and is apparently only found in areas where permissive turns are normal for double lane turns (such as South Africa or Japan).

North end of Abeno Bridge, near the Abenobashi Terminal Building ---- Street View link.

note the dotted markings indicating where to yield: there are three lanes leading to those dotted lines (outer lane is optional straight/right)...

[kphoger]

I think I've posted about this before: Japan has literally hundreds, perhaps thousands, of double permissive right turns (they drive on the left). Apart from a couple examples that I might have noted a while back, I haven't posted anymore. Today, I managed to find a triple permissive right turn in Osaka (link and image below).

This marks only the third triple permissive turn I've found (first two in South Africa here and here -- spin camera around to note signal state). Apart from maybe an isolated curb-to-curb turn, I suspect this is not something seen anywhere in North America, and is apparently only found in areas where permissive turns are normal for double lane turns (such as South Africa or Japan).

North end of Abeno Bridge, near the Abenobashi Terminal Building ---- Street View link.

note the dotted markings indicating where to yield: there are three lanes leading to those dotted lines (outer lane is optional straight/right)...

Here is GSV of three vehicles waiting their turn.
And here is a relatively clear view of the three lanes.

[jakeroot]

I think I've posted about this before: Japan has literally hundreds, perhaps thousands, of double permissive right turns (they drive on the left). Apart from a couple examples that I might have noted a while back, I haven't posted anymore. Today, I managed to find a triple permissive right turn in Osaka (link and image below).

This marks only the third triple permissive turn I've found (first two in South Africa here and here -- spin camera around to note signal state). Apart from maybe an isolated curb-to-curb turn, I suspect this is not something seen anywhere in North America, and is apparently only found in areas where permissive turns are normal for double lane turns (such as South Africa or Japan).

North end of Abeno Bridge, near the Abenobashi Terminal Building ---- Street View link.

note the dotted markings indicating where to yield: there are three lanes leading to those dotted lines (outer lane is optional straight/right)...

Here is GSV of three vehicles waiting their turn.
And here is a relatively clear view of the three lanes.

Not to crush you, but your first link is literally like 10 meters downwind from my Street View link (third paragraph)

Funniest thing to me is how differently they are designed in Japan compared to other places like Tucson, where there is some fairly strict design guidelines for permissive turns across traffic. Japan basically says "go past this point and you'll hit other cars", but positive and negative offset is apparently not an issue (although this makes them more like Colorado, where there is no strict design guidelines).

I do really like Japan's propensity to use in-intersection yield lines. These make sense to me, and I don't know why they aren't used in the US. They are fairly common in other countries.

[stevashe]

MN is a weird example, with tons of double-left FYA signals, but I don't know if they actually use the flashing phase.

I know of at least one FYA that does use the flashing phase, since I've seen it in person. I actually posted about it here before, but there wasn't streetview at the time, and I don't have a picture, but there is now: https://goo.gl/maps/NBTPF44iuPxGXmEFA. Unfortunately it only shows it with red arrows, but I assure you, it does flash! (The presence of the "Left Turn Yield on FYA" sign supports this as well.)

[jakeroot]

MN is a weird example, with tons of double-left FYA signals, but I don't know if they actually use the flashing phase.

I know of at least one FYA that does use the flashing phase, since I've seen it in person. I actually posted about it here before, but there wasn't streetview at the time, and I don't have a picture, but there is now: https://goo.gl/maps/NBTPF44iuPxGXmEFA. Unfortunately it only shows it with red arrows, but I assure you, it does flash! (The presence of the "Left Turn Yield on FYA" sign supports this as well.)

I believe you! Was it late at night?

Here's a GSV still that shows it with red arrows while the through traffic is green: https://goo.gl/maps/EmyGXW6G4hUXQDMR7

My understanding was that Minnesota was switching to all FYA displays, and operating them appropriately as needed. But that virtually all remained in protected-only mode, with just some operating with permissive phasing during off-peak (night-time only?) hours.

[kphoger]

MN is a weird example, with tons of double-left FYA signals, but I don't know if they actually use the flashing phase.

Rogers Dr NB @ Diamond Lake Rd, Rogers, MN – imagery from July 2019

[mrsman]

MN is a weird example, with tons of double-left FYA signals, but I don't know if they actually use the flashing phase.

I know of at least one FYA that does use the flashing phase, since I've seen it in person. I actually posted about it here before, but there wasn't streetview at the time, and I don't have a picture, but there is now: https://goo.gl/maps/NBTPF44iuPxGXmEFA. Unfortunately it only shows it with red arrows, but I assure you, it does flash! (The presence of the "Left Turn Yield on FYA" sign supports this as well.)

I believe you! Was it late at night?

Here's a GSV still that shows it with red arrows while the through traffic is green: https://goo.gl/maps/EmyGXW6G4hUXQDMR7

My understanding was that Minnesota was switching to all FYA displays, and operating them appropriately as needed. But that virtually all remained in protected-only mode, with just some operating with permissive phasing during off-peak (night-time only?) hours.

It seems that the next intersection further south has a double left with FYA allowing a permissive left turn.  The FYA is blank (which likely means that it occurred while the FYA was flashing and the camera captured it during the off mode).  There is a car making a turn while cross traffic is coming.

https://www.google.com/maps/@44.8560521,-93.3631234,3a,73.1y,162.26h,78.98t/data=!3m6!1e1!3m4!1sAlbLLA0aAj1G90cLQ4x2gg!2e0!7i16384!8i8192?hl=en

[jakeroot]

^^^
Sweet, nice find. Both of you.

There's also this classic in Eden Prairie with an option lane: https://goo.gl/maps/KyCQYU8cimcm1VFv9

I think we can surmise, with great certainty, that most in the state do not operate with permissive phasing during daylight hours. I think the question is whether they are also disabled during night hours.

[kphoger]

It seems that the next intersection further south has a double left with FYA allowing a permissive left turn.  The FYA is blank (which likely means that it occurred while the FYA was flashing and the camera captured it during the off mode).  There is a car making a turn while cross traffic is coming.

https://www.google.com/maps/@44.8560521,-93.3631234,3a,73.1y,162.26h,78.98t/data=!3m6!1e1!3m4!1sAlbLLA0aAj1G90cLQ4x2gg!2e0!7i16384!8i8192?hl=en

If you move back one step, it's flashing yellow.

[Amtrakprod]

Not permissive but close?

https://www.google.com/maps/@42.4793074,-71.1520325,3a,75y,59.72h,90.07t/data=!3m6!1e1!3m4!1stTjgz-pa2o1vgihJgokqWg!2e0!7i16384!8i8192

[jakeroot]

Not permissive but close?

https://www.google.com/maps/@42.4793074,-71.1520325,3a,75y,59.72h,90.07t/data=!3m6!1e1!3m4!1stTjgz-pa2o1vgihJgokqWg!2e0!7i16384!8i8192

Close, but not really in the way that I'm looking for in this thread.

[jakeroot]

I was going to avoid mentioning any that I found in Minnesota, given their propensity to use FYAs even when the plan is to use protected-only phasing, but I did find one today that was actually flashing:

Westbound Maryland Ave to southbound I-35E, St Paul

Have I been mistaken in assuming that, despite the double FYA being hilariously common in MN, that they almost never use permissive phasing? Or is it more common than I realize in certain conditions (on-ramp left turns, late at night, etc).

[jakeroot]

Finally found an example in Hawaii:

Southbound Victoria Street @ King St; Honolulu (spin camera to see opposing signal state)

I find it odd that the solid line directs the outer left turn lane into the farther lanes, ostensibly the area where the opposing right turn would turn into it. All despite King St being 5 or 6 lanes eastbound.

[Amtrakprod]

In NYC: https://www.google.com/maps/@40.7163818,-73.9959115,3a,46.2y,233.81h,89.73t/data=!3m6!1e1!3m4!1sOyPlYT-kTl0ph4T1-JRifw!2e0!7i16384!8i8192

[jakeroot]

In NYC: https://www.google.com/maps/@40.7163818,-73.9959115,3a,46.2y,233.81h,89.73t/data=!3m6!1e1!3m4!1sOyPlYT-kTl0ph4T1-JRifw!2e0!7i16384!8i8192

An interesting case of "we need two lanes for both movements, but there's no way to fit split phasing into this intersection". So they just option the center lane and keep it protected/permissive. Very nice, NYCDOT.

[mrsman]

In NYC: https://www.google.com/maps/@40.7163818,-73.9959115,3a,46.2y,233.81h,89.73t/data=!3m6!1e1!3m4!1sOyPlYT-kTl0ph4T1-JRifw!2e0!7i16384!8i8192

An interesting case of "we need two lanes for both movements, but there's no way to fit split phasing into this intersection". So they just option the center lane and keep it protected/permissive. Very nice, NYCDOT.

This occurs in a few places in NYC for exactly the reasons you state.  Generally, these involve a lagging left and opposing left being prohibited, so that  someone stuck behind a car going left in the option lane can be assured that they will have the opportunity to go at the end of the cycle.  Prohibiting the opposing left avoids a yellow trap problem that would otherwise be caused with the lagging left.

As this is right near the entrance to the Manhattan bridge, and a busy area, it is very rare that someone would be able to make the permitted turn, so effectively the turns only occur during the protected phase.  But theoretically, yes, turns are permitted on green orb when yielding to opposing traffic.

[jakeroot]

In NYC: https://www.google.com/maps/@40.7163818,-73.9959115,3a,46.2y,233.81h,89.73t/data=!3m6!1e1!3m4!1sOyPlYT-kTl0ph4T1-JRifw!2e0!7i16384!8i8192

An interesting case of "we need two lanes for both movements, but there's no way to fit split phasing into this intersection". So they just option the center lane and keep it protected/permissive. Very nice, NYCDOT.

This occurs in a few places in NYC for exactly the reasons you state.  Generally, these involve a lagging left and opposing left being prohibited, so that  someone stuck behind a car going left in the option lane can be assured that they will have the opportunity to go at the end of the cycle.  Prohibiting the opposing left avoids a yellow trap problem that would otherwise be caused with the lagging left.

As this is right near the entrance to the Manhattan bridge, and a busy area, it is very rare that someone would be able to make the permitted turn, so effectively the turns only occur during the protected phase.  But theoretically, yes, turns are permitted on green orb when yielding to opposing traffic.

It's kind of crazy to me to think that it was only a single lane left turn before. I would have to assume that this isn't the primary entrance to the Manhattan Bridge.

Anyone in the area care to comment how split the center lane is in terms of whether it's primarily used by left turns or through traffic?

[mrsman]

In NYC: https://www.google.com/maps/@40.7163818,-73.9959115,3a,46.2y,233.81h,89.73t/data=!3m6!1e1!3m4!1sOyPlYT-kTl0ph4T1-JRifw!2e0!7i16384!8i8192

An interesting case of "we need two lanes for both movements, but there's no way to fit split phasing into this intersection". So they just option the center lane and keep it protected/permissive. Very nice, NYCDOT.

This occurs in a few places in NYC for exactly the reasons you state.  Generally, these involve a lagging left and opposing left being prohibited, so that  someone stuck behind a car going left in the option lane can be assured that they will have the opportunity to go at the end of the cycle.  Prohibiting the opposing left avoids a yellow trap problem that would otherwise be caused with the lagging left.

As this is right near the entrance to the Manhattan bridge, and a busy area, it is very rare that someone would be able to make the permitted turn, so effectively the turns only occur during the protected phase.  But theoretically, yes, turns are permitted on green orb when yielding to opposing traffic.

It's kind of crazy to me to think that it was only a single lane left turn before. I would have to assume that this isn't the primary entrance to the Manhattan Bridge.

Anyone in the area care to comment how split the center lane is in terms of whether it's primarily used by left turns or through traffic?

From my experience, it seems like most people in the middle lane go to the bridge, instead of continuing down Bowery.  An exception may be during the morning hours as more traffic is likely headed toward Downtown and not to Brooklyn.

Fewer people may be headed south on Bowery, given the closure of Park Row near police headquarters since 9/11.  Perhaps it was this closure that caused more traffic headed Downtown to use FDR or Broadway, while having more people using the bridge take Bowery.  Bowery is still not the main flow of traffic into the bridge, far more of the traffic is headed from the western side of the area and taking Canal, especially traffic from the Holland Tunnel.

[jakeroot]

From my experience, it seems like most people in the middle lane go to the bridge, instead of continuing down Bowery.  An exception may be during the morning hours as more traffic is likely headed toward Downtown and not to Brooklyn.

This seems like an important point, and where option-lane setups can actually be quite ideal. The flow of traffic not necessarily even throughout the day, so allowing traffic to determine the dominant movement of the center lane based on time of day allows a great deal of flexibility without the added cost (and likely conversion to protected-only phasing) of a double left + double through setup.

The only real issues right now, if I had to guess, would be (A) traffic cops making the overall setup and phasing totally redundant (unless they are there to preserve order and let the signals do the work...I don't know how NYC operates in this regard); (B) the potential for pedestrian collisions (reduced by the presence of the police in A); and (C) the potential for rear-end crashes if someone in the morning hours turns left from the middle lane, and gets hit from the rear by a car used to center lane traffic continuing south along Bowery. For B and C, I think NYC drivers are well-enough versed in avoiding these situations that neither are likely major issues.

[jakeroot]

Found another in California. Suburban Pleasanton, totally surrounded by protected signals as is the norm in Northern California:

https://goo.gl/maps/oyKJ8JF5sfP9JPJq9

The center lane is an optional left/straight lane.

[mrsman]

Found another in California. Suburban Pleasanton, totally surrounded by protected signals as is the norm in Northern California:

https://goo.gl/maps/oyKJ8JF5sfP9JPJq9

The center lane is an optional left/straight lane.

Good application of double permissive here.  Even in states that are generally concerned about allowing double permissive, which CA generally is, there is a realization that where the opposing traffic comes from a really low traffic street, especially a residential one without an outlet and only a handful of houses, there is no problem in allowing the permissive turn - as is generally the case if this were a T intersection.  From this view of the intersection, you can see that on a green light, there is no traffic coming from the residential street at all and that is likely the case for a large part of the day.

https://www.google.com/maps/@37.6944605,-121.8781282,3a,75y,332.9h,82.29t/data=!3m6!1e1!3m4!1snpZHTke1Oglrxh9qE_RFzA!2e0!7i13312!8i6656

[mrsman]

From my experience, it seems like most people in the middle lane go to the bridge, instead of continuing down Bowery.  An exception may be during the morning hours as more traffic is likely headed toward Downtown and not to Brooklyn.

This seems like an important point, and where option-lane setups can actually be quite ideal. The flow of traffic not necessarily even throughout the day, so allowing traffic to determine the dominant movement of the center lane based on time of day allows a great deal of flexibility without the added cost (and likely conversion to protected-only phasing) of a double left + double through setup.

The only real issues right now, if I had to guess, would be (A) traffic cops making the overall setup and phasing totally redundant (unless they are there to preserve order and let the signals do the work...I don't know how NYC operates in this regard); (B) the potential for pedestrian collisions (reduced by the presence of the police in A); and (C) the potential for rear-end crashes if someone in the morning hours turns left from the middle lane, and gets hit from the rear by a car used to center lane traffic continuing south along Bowery. For B and C, I think NYC drivers are well-enough versed in avoiding these situations that neither are likely major issues.

Another thing to also keep in mind for NYC (and many other cities as well) which has a big problem of illegal parking and double parking.  Converting the street to 4 SB lanes: 2 left onto the bridge and 2 continuing southbound can only be done cheaply by prohibiting parking for about half a block north of the Bowery/Canal intersection.  [I assume that widening the street by narrowing the sidewalk is not feasible at all.]  But given the rampant parking issues, the right thru lane, being against the curb, would be constantly blocked under the 2 left and 2 SB setup.  So to achieve 2 lanes south with 2 lanes left, and maintain a regular parking lane on both sides of the street, having 3 SB lanes with the middle lane serve as an optional straight/left is the only way to do it, and that's what they did.