Double left turns with permissive phasing

[fwydriver405]

So there was even more? Very interesting. Did you live in the area? Curious because that KRON4 video was from soon after the signal was modified, and the story seems to about the massive tailbacks being caused by that left turn. I would be interested in knowing how that signal modification has affected traffic flow. Usually the main arguments against these are either too many crashes, or pedestrian conflicts. But there doesn't seem to be that much oncoming traffic (total non-scientific observation), and there is no pedestrian crossing. So why the change? hmm.

I observed those double left turns when I was on holiday to Downtown San Francisco in 2013 and 2015 and passed thru Harrison and 1st Ave to get on to the Bay Bridge, as well as passing thru Van Ness Ave and Broadway on our way to the Golden Gate Bridge. The rest of the intersections were observed during Stanley Robert's former "People Behaving Badly" series when he used to work at KRON4.

I think that the bus lane would probably end at Greenwhich (one block south of Lombard).  They need some way to allow for that massive left turn, and there would be no additional room for a bus lane.  At Broadway, there will probably be a protected-only left (to be made from the lane that is to the right of the bus lane), but it may be limited to one lane.

Does Downtown SF use flashing yellow arrow signals for permissive turns at all?

Not to be confused with the flashing yellow balls that SF uses at some intersections:
Height and Octavia (which should really an all-arrow FYA on EB Haight)
Fremont and Harrison (again, should really be all-arrow signals, red ball for the right turn)

[mrsman]

Does Downtown SF use flashing yellow arrow signals for permissive turns at all?

I'm not aware of any, but they are allowed in CA, so there should be no problem with them.

[Amtrakprod]

Lincoln NE, https://www.google.com/maps/@40.815802,-96.7083362,3a,30.1y,272.94h,93.67t/data=!3m6!1e1!3m4!1sJhHfcrOHNhFN11UqYIWagA!2e0!7i16384!8i8192

[jakeroot]

Lincoln NE, https://www.google.com/maps/@40.815802,-96.7083362,3a,30.1y,272.94h,93.67t/data=!3m6!1e1!3m4!1sJhHfcrOHNhFN11UqYIWagA!2e0!7i16384!8i8192

That's a very interesting example. There is technically no oncoming traffic that would proceed directly past the yielding traffic, but traffic does still need to yield to oncoming drivers (turning right into their destined lanes), as well as pedestrians. In that sense, it kind of hits the spirit of this thread. There are flashing yellow arrows for both approaches, which is fairly unusual for this kind of downtown intersection, but the oncoming traffic also has a flashing yellow arrow. I'm very interested to see what the "failure to yield" rates are for the double left turn, since both directions have flashing yellow arrows but the dominant direction, in these situations, tends to take priority (as odd as that sounds; more based on my experience to be honest).

That said, I think situations like this, involving one-way downtown streets, are fairly common. Spokane, WA has a lot of double left and double right turns downtown. I'm sure at least one or two requires yielding to peds and vehicles.

[RestrictOnTheHanger]

Bethpage/Hicksville, NY

https://maps.app.goo.gl/RSYTE3MHjgfJ6Vm59

[jakeroot]

Bethpage/Hicksville, NY

https://maps.app.goo.gl/RSYTE3MHjgfJ6Vm59

Woah! That's cool. I know that NY has some, but almost all that I've seen do not have an oncoming left, or are turns onto one-way streets. Great find!

[RestrictOnTheHanger]

Bethpage/Hicksville, NY

https://maps.app.goo.gl/RSYTE3MHjgfJ6Vm59

Woah! That's cool. I know that NY has some, but almost all that I've seen do not have an oncoming left, or are turns onto one-way streets. Great find!

Another one in Garden City, same county(Nassau). A lagging double permissive turn, rare for turns onto a 2 way street.

https://maps.app.goo.gl/aW6ujm7BVdTXSD9y5

[jakeroot]

Bethpage/Hicksville, NY

https://maps.app.goo.gl/RSYTE3MHjgfJ6Vm59

Woah! That's cool. I know that NY has some, but almost all that I've seen do not have an oncoming left, or are turns onto one-way streets. Great find!

Another one in Garden City, same county(Nassau). A lagging double permissive turn, rare for turns onto a 2 way street.

https://maps.app.goo.gl/aW6ujm7BVdTXSD9y5

Another cool find. Although moderately less interesting, given the lack of an opposing left turn. Still, yet another good find in New York.

[fwydriver405]

Atlanta, GA at Cascade Road on the onramp to I-285 N. Double doghouse configuration, middle lane is a left/thru lane. Not sure how many more double permissive lefts are there in the Atlanta metro area...

If FYA's were to be used at that intersection with the current lane configuration and phasing, would the leftmost signal be an FYA, middle doghouse, and right 3-section signal consisting of all balls?

[jakeroot]

Atlanta, GA at Cascade Road on the onramp to I-285 N. Double doghouse configuration, middle lane is a left/thru lane. Not sure how many more double permissive lefts are there in the Atlanta metro area...

If FYA's were to be used at that intersection with the current lane configuration and phasing, would the leftmost signal be an FYA, middle doghouse, and right 3-section signal consisting of all balls?

Looks like it might have been removed: the green arrow is no longer activating for the right-most doghouse, and the option lane arrow has disappeared from the pavement. But the option lane sign is still overhead (see all three in this link). Honestly, this is how all option lane double left turns onto on-ramps should operate. I've seen some that are split phased. To force through traffic to stop just because you have an option lane seems idiotic, especially with the excellent visibility that left turning traffic would typically have (although the shrubs in this median do hamper visibility a bit).

Typically, with option lanes, I think you'd see it where the left-most signal was an FYA, and middle signal was a doghouse with an FYA instead of regular arrows, and a regular 3-section signal on the right. This is how it's done at this intersection in MN.

[Amtrakprod]

Atlanta, GA at Cascade Road on the onramp to I-285 N. Double doghouse configuration, middle lane is a left/thru lane. Not sure how many more double permissive lefts are there in the Atlanta metro area...

If FYA's were to be used at that intersection with the current lane configuration and phasing, would the leftmost signal be an FYA, middle doghouse, and right 3-section signal consisting of all balls?

It would likely look like this: https://www.google.com/maps/@29.4387288,-98.4609631,3a,28.2y,2.68h,94.06t/data=!3m6!1e1!3m4!1sEnNKghe8vkX2j_TSRMDKgw!2e0!7i16384!8i8192

[Amtrakprod]

Atlanta, GA at Cascade Road on the onramp to I-285 N. Double doghouse configuration, middle lane is a left/thru lane. Not sure how many more double permissive lefts are there in the Atlanta metro area...

If FYA's were to be used at that intersection with the current lane configuration and phasing, would the leftmost signal be an FYA, middle doghouse, and right 3-section signal consisting of all balls?

Looks like it might have been removed: the green arrow is no longer activating for the right-most doghouse, and the option lane arrow has disappeared from the pavement. But the option lane sign is still overhead (see all three in this link). Honestly, this is how all option lane double left turns onto on-ramps should operate. I've seen some that are split phased. To force through traffic to stop just because you have an option lane seems idiotic, especially with the excellent visibility that left turning traffic would typically have (although the shrubs in this median do hamper visibility a bit).

Typically, with option lanes, I think you'd see it where the left-most signal was an FYA, and middle signal was a doghouse with an FYA instead of regular arrows, and a regular 3-section signal on the right. This is how it's done at this intersection in MN.

It also is totally off here: https://www.google.com/maps/@33.7230047,-84.5022569,3a,75y,117.78h,77.02t/data=!3m6!1e1!3m4!1siQe-f0CXUSJHZZ-DNofe2w!2e0!7i16384!8i8192

[roadfro]

Looks like it might have been removed: the green arrow is no longer activating for the right-most doghouse, and the option lane arrow has disappeared from the pavement. But the option lane sign is still overhead (see all three in this link). Honestly, this is how all option lane double left turns onto on-ramps should operate. I've seen some that are split phased. To force through traffic to stop just because you have an option lane seems idiotic, especially with the excellent visibility that left turning traffic would typically have (although the shrubs in this median do hamper visibility a bit).

Well, you're forcing some traffic to stop regardless. In the typical split-phase setup, the opposing through traffic has to stop. In this kind of scenario with an option lane not employing split phasing, any left turning traffic in the option lane waiting for gap in opposing traffic will block any through traffic behind them in the option lane. If this happens to be on a coordinated signal corridor, that permissive feature of the option lane is likely to break up the platoon riding the green wave.

[jakeroot]

Looks like it might have been removed: the green arrow is no longer activating for the right-most doghouse, and the option lane arrow has disappeared from the pavement. But the option lane sign is still overhead (see all three in this link). Honestly, this is how all option lane double left turns onto on-ramps should operate. I've seen some that are split phased. To force through traffic to stop just because you have an option lane seems idiotic, especially with the excellent visibility that left turning traffic would typically have (although the shrubs in this median do hamper visibility a bit).

Well, you're forcing some traffic to stop regardless. In the typical split-phase setup, the opposing through traffic has to stop. In this kind of scenario with an option lane not employing split phasing, any left turning traffic in the option lane waiting for gap in opposing traffic will block any through traffic behind them in the option lane. If this happens to be on a coordinated signal corridor, that permissive feature of the option lane is likely to break up the platoon riding the green wave.

Split phasing would force all traffic to stop, regardless. Allowing through traffic to proceed might block the option lane, or it might not. Clearly, permissive phasing allows for greater flexibility and much easier coordination. This flexibility is especially clear when you consider the time of day. During rush hour, the option lane might favor left turning traffic. During off hours, it might favor through traffic instead. Again, there is flexibility that you don't have with split-phasing.

The only legit argument might be safety, and even that's a stretch when you consider how good the visibility would be.

[jakeroot]

Atlanta, GA at Cascade Road on the onramp to I-285 N. Double doghouse configuration, middle lane is a left/thru lane. Not sure how many more double permissive lefts are there in the Atlanta metro area...

If FYA's were to be used at that intersection with the current lane configuration and phasing, would the leftmost signal be an FYA, middle doghouse, and right 3-section signal consisting of all balls?

Looks like it might have been removed: the green arrow is no longer activating for the right-most doghouse, and the option lane arrow has disappeared from the pavement. But the option lane sign is still overhead (see all three in this link). Honestly, this is how all option lane double left turns onto on-ramps should operate. I've seen some that are split phased. To force through traffic to stop just because you have an option lane seems idiotic, especially with the excellent visibility that left turning traffic would typically have (although the shrubs in this median do hamper visibility a bit).

Typically, with option lanes, I think you'd see it where the left-most signal was an FYA, and middle signal was a doghouse with an FYA instead of regular arrows, and a regular 3-section signal on the right. This is how it's done at this intersection in MN.

It also is totally off here: https://www.google.com/maps/@33.7230047,-84.5022569,3a,75y,117.78h,77.02t/data=!3m6!1e1!3m4!1siQe-f0CXUSJHZZ-DNofe2w!2e0!7i16384!8i8192

I saw that as well. No idea what's going on at that intersection.

[fwydriver405]

Atlanta, GA at Cascade Road on the onramp to I-285 N. Double doghouse configuration, middle lane is a left/thru lane. Not sure how many more double permissive lefts are there in the Atlanta metro area...

If FYA's were to be used at that intersection with the current lane configuration and phasing, would the leftmost signal be an FYA, middle doghouse, and right 3-section signal consisting of all balls?

Looks like it might have been removed: the green arrow is no longer activating for the right-most doghouse, and the option lane arrow has disappeared from the pavement. But the option lane sign is still overhead (see all three in this link). Honestly, this is how all option lane double left turns onto on-ramps should operate. I've seen some that are split phased. To force through traffic to stop just because you have an option lane seems idiotic, especially with the excellent visibility that left turning traffic would typically have (although the shrubs in this median do hamper visibility a bit).

Typically, with option lanes, I think you'd see it where the left-most signal was an FYA, and middle signal was a doghouse with an FYA instead of regular arrows, and a regular 3-section signal on the right. This is how it's done at this intersection in MN.

It also is totally off here: https://www.google.com/maps/@33.7230047,-84.5022569,3a,75y,117.78h,77.02t/data=!3m6!1e1!3m4!1siQe-f0CXUSJHZZ-DNofe2w!2e0!7i16384!8i8192

I saw that as well. No idea what's going on at that intersection.

Here's the permissive phase as of Sept. 2019. It's hard to see, but there is no arrow where the doghouses are, and the oncoming signal has a green. The middle doghouse is still out in this example...

[mrsman]

Looks like it might have been removed: the green arrow is no longer activating for the right-most doghouse, and the option lane arrow has disappeared from the pavement. But the option lane sign is still overhead (see all three in this link). Honestly, this is how all option lane double left turns onto on-ramps should operate. I've seen some that are split phased. To force through traffic to stop just because you have an option lane seems idiotic, especially with the excellent visibility that left turning traffic would typically have (although the shrubs in this median do hamper visibility a bit).

Well, you're forcing some traffic to stop regardless. In the typical split-phase setup, the opposing through traffic has to stop. In this kind of scenario with an option lane not employing split phasing, any left turning traffic in the option lane waiting for gap in opposing traffic will block any through traffic behind them in the option lane. If this happens to be on a coordinated signal corridor, that permissive feature of the option lane is likely to break up the platoon riding the green wave.

Split phasing would force all traffic to stop, regardless. Allowing through traffic to proceed might block the option lane, or it might not. Clearly, permissive phasing allows for greater flexibility and much easier coordination. This flexibility is especially clear when you consider the time of day. During rush hour, the option lane might favor left turning traffic. During off hours, it might favor through traffic instead. Again, there is flexibility that you don't have with split-phasing.

The only legit argument might be safety, and even that's a stretch when you consider how good the visibility would be.

Split phasing is almost always worse for overall traffic delay.  The exception is if the left turn of both directions are really heavy movements.  Split-phasing takes away too much time from the other phases of the intersection.

A well coordinated permissive left turn with an option lane can work really well, and overall far less delay than split phasing.  This is especially true if the left turn is lagging and the opposing left is prohibited.

[jakeroot]

I have located another in California, this one adjacent to the UC Berkeley Campus; it does involve an option lane but is otherwise completely normal:

Eastbound University Ave @ Oxford St, Berkeley, CA (click forward into the intersection to see the other direction showing green).

The left turn is complete with a "LEFT TURNS YIELD" sign on the left.

This installation seems to be the only double left turn yield along public roads outside of SF-proper anywhere in California, at least to my knowledge (I would have said all of California prior to fwydriver405 alerting us to those in SF). The only other one outside of SF-proper is in Santa Clara, but it's from a driveway).

[mrsman]

I have located another in California, this one adjacent to the UC Berkeley Campus; it does involve an option lane but is otherwise completely normal:

Eastbound University Ave @ Oxford St, Berkeley, CA (click forward into the intersection to see the other direction showing green).

The left turn is complete with a "LEFT TURNS YIELD" sign on the left.

This installation seems to be the only double left turn yield along public roads outside of SF-proper anywhere in California, at least to my knowledge (I would have said all of California prior to fwydriver405 alerting us to those in SF). The only other one outside of SF-proper is in Santa Clara, but it's from a driveway).

While I normally consider a left turn yield on green sign(or similar) language to be somewhat superfluous, I think it is necessary here.  Given that permissive double lefts are so rare in California, a lot of people may just simply make the left on green without yielding, if it weren't for the sign.  Another oddity about this intersection is that there is no green arrow at all in this direction.  Left turns must always yield, there is no protective phase - which again is rare for any CA double left, including the ones in SF and the ones that used to exist in L.A.

Take a look at the intersection of Beverly/Palm/Santa Monica in Beverly Hills:

https://www.google.com/maps/@34.0773825,-118.3957656,3a,75y,142.85h,99.82t/data=!3m6!1e1!3m4!1sTe7bucP3okOd3P-d7JxzgA!2e0!7i13312!8i6656

This intersection is split-phased, Beverly and Palm have greens at separate times.  Normally that means that the lefts are protected at all times that there is a green ball showing.  But, when a pedestrian has pushed to call to cross the street, the green ball shows without an arrow.  So left turners will have to yield to peds here, but not opposing traffic.  If a pedestrian did not push the button, the drivers will see a green arrow and have a protected turn.

Now the Beverly side is the double left, and I believe the left is always protected with an arrow from that perspective, but having driven frequently by this intersection for many years when I lived in L.A. (but over 20 years ago), I know that there's a lot to be watchful for.  It is kind of unnerving to see a green orb and think?  do I have the ROW to turn? why aren't the opposing traffic advancing? do I have to still watch for peds?  (A number of years ago there were no arrows at all, so this new setup is definitely better.)

https://www.google.com/maps/@34.0771874,-118.395557,3a,75y,195.66h,92.94t/data=!3m6!1e1!3m4!1sQZki2cevvqUF8YAx51k9Cw!2e0!7i13312!8i6656



A sign like this (below) would probably make things a lot better.  This intersection is also split-phased.

https://www.google.com/maps/@39.0153738,-77.0788889,3a,75y,309.57h,101.14t/data=!3m6!1e1!3m4!1seQ-yT27Tmk1cBWHas8h5gA!2e0!7i16384!8i8192

The sign says "left turns yield to pedestrians on green".  So it's clear that it allows for split-phasing, but if there is no green arrow, yield to the pedestrians.

[jakeroot]

Found one of these for the first time last weekend, on the east side of Sioux Falls, along a section of SD-42 that was reconstructed last year.  I'm guessing they're more commonly found in states with universally low traffic volumes.



Discussions are more enjoyable with photos 

Nice! I would guess that the side-street in the photo with the dual-FYA setup (Highline Ave) is relatively quiet, which is actually a great reason to install this type of signal: they can allow side-street traffic to clear far quicker than with protected-only phasing, giving more green time to the primary artery (Arrowhead Parkway in this case).

I can't recall hearing of any others in South Dakota, so I'm guessing their state DOT must not have an objection to these types of installs. Especially as this is along a state route. Of course, this installation might have been installed/maintained by Sioux Falls directly, so that's not something I could be sure of.

Following up on Sioux Falls.

There is another at the off-ramp from northbound I-29 at Maple & Russell streets (Exit 81). This one has been in place for as long as street view imagery has been occuring, and the double left turn looks to have been in place since the early 2000s, when the interchange was reconstructed from a diamond into a parclo.

I'm going to assume that, this being the off-ramp from a state-maintained road, that this is a state-maintained intersection. Given this intersection, and other new one at Highline and SD-42 (now on street view), I think it's safe to assume that SDDOT has given the thumbs-up to this style of phasing. It would appear that its use is conditional, based on number of lanes and the overall setup (although this is true for regular permissive left turns as well), as other double left turns in Sioux Falls use protected-only phasing (at least for those that I've located).

As a side-note: this is definitely one of my favorite interchanges in the US. There is something very elegant about the way it was designed (the placement of the free-flow ramps especially). South Dakota also has excellent signal placement, and the northbound off-ramp has a double permissive left. Just a lot of "good" things going on here, from my perspective.

https://goo.gl/maps/essAqyJ3UehQjUQe6

[jakeroot]

I have located another in California, this one adjacent to the UC Berkeley Campus; it does involve an option lane but is otherwise completely normal:

Eastbound University Ave @ Oxford St, Berkeley, CA (click forward into the intersection to see the other direction showing green).

The left turn is complete with a "LEFT TURNS YIELD" sign on the left.

This installation seems to be the only double left turn yield along public roads outside of SF-proper anywhere in California, at least to my knowledge (I would have said all of California prior to fwydriver405 alerting us to those in SF). The only other one outside of SF-proper is in Santa Clara, but it's from a driveway).

While I normally consider a left turn yield on green sign (or similar) language to be somewhat superfluous, I think it is necessary here.  Given that permissive double lefts are so rare in California, a lot of people may just simply make the left on green without yielding, if it weren't for the sign.  Another oddity about this intersection is that there is no green arrow at all in this direction.  Left turns must always yield, there is no protective phase - which again is rare for any CA double left, including the ones in SF and the ones that used to exist in L.A.

Take a look at the intersection of Beverly/Palm/Santa Monica in Beverly Hills:

https://www.google.com/maps/@34.0773825,-118.3957656,3a,75y,142.85h,99.82t/data=!3m6!1e1!3m4!1sTe7bucP3okOd3P-d7JxzgA!2e0!7i13312!8i6656

This intersection is split-phased, Beverly and Palm have greens at separate times.  Normally that means that the lefts are protected at all times that there is a green ball showing.  But, when a pedestrian has pushed to call to cross the street, the green ball shows without an arrow.  So left turners will have to yield to peds here, but not opposing traffic.  If a pedestrian did not push the button, the drivers will see a green arrow and have a protected turn.

Now the Beverly side is the double left, and I believe the left is always protected with an arrow from that perspective, but having driven frequently by this intersection for many years when I lived in L.A. (but over 20 years ago), I know that there's a lot to be watchful for.  It is kind of unnerving to see a green orb and think?  do I have the ROW to turn? why aren't the opposing traffic advancing? do I have to still watch for peds?  (A number of years ago there were no arrows at all, so this new setup is definitely better.)

https://www.google.com/maps/@34.0771874,-118.395557,3a,75y,195.66h,92.94t/data=!3m6!1e1!3m4!1sQZki2cevvqUF8YAx51k9Cw!2e0!7i13312!8i6656



A sign like this (below) would probably make things a lot better.  This intersection is also split-phased.

https://www.google.com/maps/@39.0153738,-77.0788889,3a,75y,309.57h,101.14t/data=!3m6!1e1!3m4!1seQ-yT27Tmk1cBWHas8h5gA!2e0!7i16384!8i8192

The sign says "left turns yield to pedestrians on green".  So it's clear that it allows for split-phasing, but if there is no green arrow, yield to the pedestrians.

Not sure why I keep missing your posts.

Seems that, of all the double permissive left turns without dedicated turn lanes (so maybe one dedicated left turn lane, adjacent to an optional left/straight lane), they are largely permissive-only. The exception seems to be those onto one-way streets, where a lagging green arrow is most common.

An example of the above (permissive-only) is in Seattle, from NE 44th onto Montlake Blvd:

https://goo.gl/maps/5QScXHpcBvYJTQkw7

In 98% of municipalities, this would be split-phased, but it is permissive-only here. An advanced left could be used, but there is no reason as there is little oncoming traffic. Most of the time, this intersection operates as a T-intersection (practically, anyways). At any rate, a "LEFT TURNS MUST YIELD" would be a nice sign, short of changing the operation of the intersection altogether.

I have not seen an intersection operate like those two in Los Angeles and Maryland, but it is a very logical setup for an intersection that could otherwise be very low capacity when a pedestrian push-button is selected. I would be very interested to know if, in those municipalities that setup intersections in this manner, if it's acceptable to use permissive phasing with two left turn lanes, but only when the pedestrian walk sign is on (so traffic is only yielding to pedestrians, not through traffic). If the double left turn is the heaviest movement of the split-phase, and a pedestrian wanted to cross along that edge of the intersection (conflicting with the double left turn), that would, in a typical split-phase intersection, force the double left turn to wait for the entire walk cycle, all the while waiting for oncoming traffic (perhaps no one coming at all).

In Federal Way, WA, there is an offset intersection that is ordinarily split-phased, but has flashing yellow arrows for the intersecting streets when the walk signs are activated (very similar to those in LA and Maryland, but a little different). I took a video a few years (and a few pounds ) ago. What I don't recall is whether both walk signs activate simultaneously, or if one of the oncoming directions still has a green light during the walk phase. I need to go back and get another video!

https://youtu.be/jEVhAABx0q4

[mrsman]

I have located another in California, this one adjacent to the UC Berkeley Campus; it does involve an option lane but is otherwise completely normal:

Eastbound University Ave @ Oxford St, Berkeley, CA (click forward into the intersection to see the other direction showing green).

The left turn is complete with a "LEFT TURNS YIELD" sign on the left.

This installation seems to be the only double left turn yield along public roads outside of SF-proper anywhere in California, at least to my knowledge (I would have said all of California prior to fwydriver405 alerting us to those in SF). The only other one outside of SF-proper is in Santa Clara, but it's from a driveway).

While I normally consider a left turn yield on green sign (or similar) language to be somewhat superfluous, I think it is necessary here.  Given that permissive double lefts are so rare in California, a lot of people may just simply make the left on green without yielding, if it weren't for the sign.  Another oddity about this intersection is that there is no green arrow at all in this direction.  Left turns must always yield, there is no protective phase - which again is rare for any CA double left, including the ones in SF and the ones that used to exist in L.A.

Take a look at the intersection of Beverly/Palm/Santa Monica in Beverly Hills:

https://www.google.com/maps/@34.0773825,-118.3957656,3a,75y,142.85h,99.82t/data=!3m6!1e1!3m4!1sTe7bucP3okOd3P-d7JxzgA!2e0!7i13312!8i6656

This intersection is split-phased, Beverly and Palm have greens at separate times.  Normally that means that the lefts are protected at all times that there is a green ball showing.  But, when a pedestrian has pushed to call to cross the street, the green ball shows without an arrow.  So left turners will have to yield to peds here, but not opposing traffic.  If a pedestrian did not push the button, the drivers will see a green arrow and have a protected turn.

Now the Beverly side is the double left, and I believe the left is always protected with an arrow from that perspective, but having driven frequently by this intersection for many years when I lived in L.A. (but over 20 years ago), I know that there's a lot to be watchful for.  It is kind of unnerving to see a green orb and think?  do I have the ROW to turn? why aren't the opposing traffic advancing? do I have to still watch for peds?  (A number of years ago there were no arrows at all, so this new setup is definitely better.)

https://www.google.com/maps/@34.0771874,-118.395557,3a,75y,195.66h,92.94t/data=!3m6!1e1!3m4!1sQZki2cevvqUF8YAx51k9Cw!2e0!7i13312!8i6656



A sign like this (below) would probably make things a lot better.  This intersection is also split-phased.

https://www.google.com/maps/@39.0153738,-77.0788889,3a,75y,309.57h,101.14t/data=!3m6!1e1!3m4!1seQ-yT27Tmk1cBWHas8h5gA!2e0!7i16384!8i8192

The sign says "left turns yield to pedestrians on green".  So it's clear that it allows for split-phasing, but if there is no green arrow, yield to the pedestrians.

Not sure why I keep missing your posts.

Seems that, of all the double permissive left turns without dedicated turn lanes (so maybe one dedicated left turn lane, adjacent to an optional left/straight lane), they are largely permissive-only. The exception seems to be those onto one-way streets, where a lagging green arrow is most common.

An example of the above (permissive-only) is in Seattle, from NE 44th onto Montlake Blvd:

https://goo.gl/maps/5QScXHpcBvYJTQkw7

In 98% of municipalities, this would be split-phased, but it is permissive-only here. An advanced left could be used, but there is no reason as there is little oncoming traffic. Most of the time, this intersection operates as a T-intersection (practically, anyways). At any rate, a "LEFT TURNS MUST YIELD" would be a nice sign, short of changing the operation of the intersection altogether.

I have not seen an intersection operate like those two in Los Angeles and Maryland, but it is a very logical setup for an intersection that could otherwise be very low capacity when a pedestrian push-button is selected. I would be very interested to know if, in those municipalities that setup intersections in this manner, if it's acceptable to use permissive phasing with two left turn lanes, but only when the pedestrian walk sign is on (so traffic is only yielding to pedestrians, not through traffic). If the double left turn is the heaviest movement of the split-phase, and a pedestrian wanted to cross along that edge of the intersection (conflicting with the double left turn), that would, in a typical split-phase intersection, force the double left turn to wait for the entire walk cycle, all the while waiting for oncoming traffic (perhaps no one coming at all).

In Federal Way, WA, there is an offset intersection that is ordinarily split-phased, but has flashing yellow arrows for the intersecting streets when the walk signs are activated (very similar to those in LA and Maryland, but a little different). I took a video a few years (and a few pounds ) ago. What I don't recall is whether both walk signs activate simultaneously, or if one of the oncoming directions still has a green light during the walk phase. I need to go back and get another video!

https://youtu.be/jEVhAABx0q4

For most split-phased intersections, especially, when the split-phased side is a relatively narrow street, in my opinion it would be better if only one of the crosswalks were provided (i.e. prohibit crossing on one side of the street, the side with the busiest left turns).  In that sense, we can limit the amount of time of the split-phasing dramatically.

So if the westbound to southbound left is heavier than eastbound to northbound, make the westbound left the first left and allow pedestrians to only cross on the north side of the intersection.  During this first phase, westbound to southbound will have a protected left and pedestrians can cross.  During the second phase, eastbound to northbound, those drivers will have to yield to the pedestrians, but since it is the last part of the signal phase, there should be few pedestrians in the way.  Left turns should yield to pedestrians (only) and not oncoming traffic, but there should be no green arrow for this and it should be clearly delineated as such.

As far as your question regarding whether CA or MD allows a double left against pedestrians but not against traffic, I am not sure that exists.  Generally both jurisdictions do not allow permissive double lefts, although there are some exceptions that are noted on this thread.  I don't believe there is an exception to allow a permissive left on a two way street against pedestrians, but not against vehicular traffic.  Of course, if we were on a one-way street, or a T intersection, where there is no possibility of oncoming vehicular traffic, double lefts against a pedestrian crossing are common and allowed in the permissive setting.

One could surmise that the MD situation [allowing a split phase with a yield to pedestrians] could exist on a split-phase where one or both sides has a double left (or left + option lane left).  But to my knowledge, nothing like "yield to pedestrians on green" has been implemented at an intersection with a double left.  It is also not helpful that MD still doesn't employ the flashing yellow arrow, which could make some of these situations more tenable.  It should be noted that at the Connecticut/Saul intersection that I posted earlier, the left that has to yield to pedestrians is on the side with far less traffic.  The busier left of the split phase does not face a pedestrian crossing at all.

[jakeroot]

For most split-phased intersections, especially, when the split-phased side is a relatively narrow street, in my opinion it would be better if only one of the crosswalks were provided (i.e. prohibit crossing on one side of the street, the side with the busiest left turns).  In that sense, we can limit the amount of time of the split-phasing dramatically.

So if the westbound to southbound left is heavier than eastbound to northbound, make the westbound left the first left and allow pedestrians to only cross on the north side of the intersection.  During this first phase, westbound to southbound will have a protected left and pedestrians can cross.  During the second phase, eastbound to northbound, those drivers will have to yield to the pedestrians, but since it is the last part of the signal phase, there should be few pedestrians in the way.  Left turns should yield to pedestrians (only) and not oncoming traffic, but there should be no green arrow for this and it should be clearly delineated as such.

As far as your question regarding whether CA or MD allows a double left against pedestrians but not against traffic, I am not sure that exists.  Generally both jurisdictions do not allow permissive double lefts, although there are some exceptions that are noted on this thread.  I don't believe there is an exception to allow a permissive left on a two way street against pedestrians, but not against vehicular traffic.  Of course, if we were on a one-way street, or a T intersection, where there is no possibility of oncoming vehicular traffic, double lefts against a pedestrian crossing are common and allowed in the permissive setting.

One could surmise that the MD situation [allowing a split phase with a yield to pedestrians] could exist on a split-phase where one or both sides has a double left (or left + option lane left).  But to my knowledge, nothing like "yield to pedestrians on green" has been implemented at an intersection with a double left.  It is also not helpful that MD still doesn't employ the flashing yellow arrow, which could make some of these situations more tenable.  It should be noted that at the Connecticut/Saul intersection that I posted earlier, the left that has to yield to pedestrians is on the side with far less traffic.  The busier left of the split phase does not face a pedestrian crossing at all.

I think it is far more standard for split-phased intersections to have only one crosswalk along the edge adjacent to the heavier leg's through movement, but I appreciate it when agencies try and figure something else out.

I went back and filmed the intersection in that video above, so it shows the whole phase. Turns out that when someone activates the crosswalk, and the left-facing FYA activates, the oncoming green signal (for left and right turns) is also active; you can see this happening in the second half of the video, when I cross the crosswalk on the right. So other than right-turning traffic having a green signal, every other movement occurs simultaneously. This seems to miss the point of split-phasing, and the regulatory signage for the FYA does not indicate that yielding to oncoming traffic is required.

As noted by a commentor, the solid yellow to indicate the end of the permissive FYA phase is below the FYA (see 0:18). I suppose that's a bit odd.

https://youtu.be/qA7YCmfNhv4

[mrsman]

That does seem to be a weird setup, but apparently safe.  Hope it works well for Federal Way.

[jakeroot]

Another in Garden City, Kansas. Centre lane is optional:

https://goo.gl/maps/SGYFPKAxyEWgAHqv7

New install around 2011 or 2012, from the looks of it.