Double left turns with permissive phasing

[webny99]

Given that Westmoreland Drive's AADT is only ~3500 vs. ~10,000 on Westfall, my guess is it's FYA 24/7. That's no more than a handful of eastbound cars per cycle except at peak times, so probably not busy enough to warrant a protected-only phase and a great trial location for a double-left FYA.

[mrsman]

Given that Westmoreland Drive's AADT is only ~3500 vs. ~10,000 on Westfall, my guess is it's FYA 24/7. That's no more than a handful of eastbound cars per cycle except at peak times, so probably not busy enough to warrant a protected-only phase and a great trial location for a double-left FYA.

It's great that they are trying something new.  The lack of permissive double lefts around NY (other than NYC) indicates that the DOTs are nervous about the concept, so to try out something that works well in other places and is legal and helpful to traffic is great.  See if it works and then expand to other locations.

There are so many split-phased signals out there, because of a double left in one direction, that could probably be re-arranged to be permissive left given the realitiies of traffic flow.  I know of several in my area that are similar to this, where oppsing traffic is very little so permissive lefts should be totally fine.  But, alas, they are still stuck with the split-phase that delays the entire intersection.

[jakeroot]

There are a few in NYC itself unless I'm missing a bunch. I think the one at Flatbush/Tillary may be gone now that the intersection was reconfigured to have a shared through/turn lane. Queens Boulevard is still there. The one in Rochester, yeah, that's the only one Upstate. I wonder if that operates as FYA 24/7 or only part-time.

Looks like Flatbush and Tillary is still permissive. Based on the number of cars still in the intersection in my GSV link, hopefully there's a long all-red phase.

Edit: better link that actually shows what I was talking about.

[steviep24]

There are a few in NYC itself unless I'm missing a bunch. I think the one at Flatbush/Tillary may be gone now that the intersection was reconfigured to have a shared through/turn lane. Queens Boulevard is still there. The one in Rochester, yeah, that's the only one Upstate. I wonder if that operates as FYA 24/7 or only part-time.

Looks like Flatbush and Tillary is still permissive. Based on the number of cars still in the intersection in my GSV link, hopefully there's a long all-red phase.

The one at Ave U and Flatbush still appears to be a permissive double left (which was discussed in this thread ages ago.)

https://www.google.com/maps/@40.6102145,-73.9221447,3a,75y,179.81h,87.94t/data=!3m6!1e1!3m4!1svwNM06bFiNkVZZlenHfFJA!2e0!7i16384!8i8192

EDIT TO UPDATE: Just looked at the Google street view today. It's protected only now. Also, Ave U was renamed to Kings Plaza at least in that block.

[paulthemapguy]

I found this dual-left turn lane with a flashing yellow arrow in Flagstaff, Arizona, for your consideration. It is the western end of the jog in a surface route following the old route of US89 (or Arizona 89A?).

https://goo.gl/maps/e2SzA1p8gkbzQFyR9

[US 89]

I found this dual-left turn lane with a flashing yellow arrow in Flagstaff, Arizona, for your consideration. It is the western end of the jog in a surface route following the old route of US89 (or Arizona 89A?).

https://goo.gl/maps/e2SzA1p8gkbzQFyR9

That is the old route of SR 89A, which itself is the old route of US 89A. I don’t think it was ever US 89. SR 89A still exists but now hops on a concurrency with I-17 at exit 337.

[jakeroot]

I found this dual-left turn lane with a flashing yellow arrow in Flagstaff, Arizona, for your consideration. It is the western end of the jog in a surface route following the old route of US89 (or Arizona 89A?).

https://goo.gl/maps/e2SzA1p8gkbzQFyR9

It's not a flashing yellow arrow, from what I can tell. Red arrow > Yellow Arrow > Green Arrow > ??.

https://goo.gl/maps/4GALxs593eNpSPv8A

Looks like a yellow arrow on the bottom, but can't find any evidence of it being used. Maybe it flashes at night? Hmm.

[US 89]

Drove through one last week in Montgomery AL, from Interstate Park Dr west onto Perry Hill Rd south:

https://goo.gl/maps/CNEFtaS85VYnZykJ9

[jakeroot]

Drove through one last week in Montgomery AL, from Interstate Park Dr west onto Perry Hill Rd south:

https://goo.gl/maps/CNEFtaS85VYnZykJ9

I think it might be split phased. Unless you saw for sure otherwise.

[US 89]

Drove through one last week in Montgomery AL, from Interstate Park Dr west onto Perry Hill Rd south:

https://goo.gl/maps/CNEFtaS85VYnZykJ9

I think it might be split phased. Unless you saw for sure otherwise.

That would certainly make more sense, given that the other side only has one lane for all three movements. I don’t remember for sure - I was more focused on the tremendous thunderstorm that was coming through when I passed through here

[jakeroot]

I'm living in Japan now. Apart from a handful of intersections, at least here in Okinawa there are no protected right turns (Japan drives on the left, so right turns are across traffic). There are many right turns with two lanes as well, and these operate permissively just like the rest. I'm convinced there is at least one with three right turn lanes, but I haven't located one yet (I only know of one, in Tokyo). Here is an example near the Rycom Shopping Center, and one of the busiest intersections outside of Naha. It also has a westbound double left turn across the crosswalk; crossings in Japan are always concurrent with through traffic.

Most right turns have a dedicated box where traffic is designated to pull into while waiting to turn. If there is a gap, you are welcome to turn, although Japanese drivers are generally pretty conservative and don't shoot through tight gaps like back in the US. Especially because the protected phase is at the end, so there's not really a strict "need" to turn during the permissive phase. The waiting boxes are great because, effectively, half the turn is already complete when the green arrow comes on. You do have to be careful though, as the yellow lights are very short (maximum around 2 seconds, even at large intersections), so plenty of drivers are still coming at you when the green arrow comes on.

At some newer intersections, such as here in central Naha, the movement through the intersection is defined by dashed lines as well as colored pavement. In that example, the right turns following the blue pavement. This helps keep drivers in the lane as they turn, but seems much more effective than just using dashed lines when there is more than one turn lane. They are also used at single-lane turns when the turn is really long, such as here.



Unrelated to double permissive turns, but just to give you some idea of how committed the Japanese are to permissive right turns: this three-level diamond has a single intersection beneath it that operates entirely permissive with a five-second all-red phase at the end (single turns only, though). You can have up to seven or eight cars in a single file line waiting to turn.


Okinawa Expy (E58) at Route 329 Bypass by Jacob Root, on Flickr

[Hobart]

I'm living in Japan now. Apart from a handful of intersections, at least here in Okinawa there are no protected right turns (Japan drives on the left, so right turns are across traffic). There are many right turns with two lanes as well, and these operate permissively just like the rest. I'm convinced there is at least one with three right turn lanes, but I haven't located one yet (I only know of one, in Tokyo). Here is an example near the Rycom Shopping Center, and one of the busiest intersections outside of Naha. It also has a westbound double left turn across the crosswalk; crossings in Japan are always concurrent with through traffic.

Most right turns have a dedicated box where traffic is designated to pull into while waiting to turn. If there is a gap, you are welcome to turn, although Japanese drivers are generally pretty conservative and don't shoot through tight gaps like back in the US. Especially because the protected phase is at the end, so there's not really a strict "need" to turn during the permissive phase. The waiting boxes are great because, effectively, half the turn is already complete when the green arrow comes on. You do have to be careful though, as the yellow lights are very short (maximum around 2 seconds, even at large intersections), so plenty of drivers are still coming at you when the green arrow comes on.

At some newer intersections, such as here in central Naha, the movement through the intersection is defined by dashed lines as well as colored pavement. In that example, the right turns following the blue pavement. This helps keep drivers in the lane as they turn, but seems much more effective than just using dashed lines when there is more than one turn lane. They are also used at single-lane turns when the turn is really long, such as here.



Unrelated to double permissive turns, but just to give you some idea of how committed the Japanese are to permissive right turns: this three-level diamond has a single intersection beneath it that operates entirely permissive with a five-second all-red phase at the end (single turns only, though). You can have up to seven or eight cars in a single file line waiting to turn.


Okinawa Expy (E58) at Route 329 Bypass by Jacob Root, on Flickr

I'd honestly be curious to see how well this works if they tried it in the states. Probably not well, but it would definitely be interesting. It seems to me like Japan actually sets up their intersections to have permissive turns with the dashed lines at intersections, rather than America where they just kind of half-ass them in last minute and rely on people's knowledge of the rules of the road to get them through.

What's also worth mentioning is that the waiting zones for some of those turns are curved. In the states, it's generally considered bad practice to keep your wheels turned to the left when making a permissive turn so you don't get forced into oncoming traffic if you're rear ended.

Also completely unrelated, but I like how Google is so detailed that it shows a horizontal traffic signal on Japanese Google Maps.

[jakeroot]

I'd honestly be curious to see how well this works if they tried it in the states. Probably not well, but it would definitely be interesting. It seems to me like Japan actually sets up their intersections to have permissive turns with the dashed lines at intersections, rather than America where they just kind of half-ass them in last minute and rely on people's knowledge of the rules of the road to get them through.

What's also worth mentioning is that the waiting zones for some of those turns are curved. In the states, it's generally considered bad practice to keep your wheels turned to the left when making a permissive turn so you don't get forced into oncoming traffic if you're rear ended.

Also completely unrelated, but I like how Google is so detailed that it shows a horizontal traffic signal on Japanese Google Maps.

Japan 100% designs for permissive turns. The waiting boxes, the colored pavement, the green arrows at the end to catch anyone that doesn't make it...they've totally thought it through and, seeing it in person, I can confirm it's a great setup, even with two or more turn lanes.

The curved waiting zones make sense here as they don't generally design their turns with any positive offset (rare counter example here). Meaning, the medians are always to the right, no matter how wide. The curved waiting zones ensure that you pull out to an area where you can see traffic more easily. The double right turn boxes always have offset waiting lines too, so that one car doesn't block the view of another. It's all decently well designed. The whole issue with being rear-ended seems really odd to me. At least here, traffic that pulls into the right turn lanes is already slowing down, the chance of someone getting into the right turn lane and then ploughing full-speed into someone waiting seems really low. Especially at a speed high enough to cause traffic to go launching forward more than a meter at most.

Google Maps actually shows an incredible amount of detail in Japan. The horizontal traffic lights are great too, but they had all the extra detail (like exact roadway geometry) way before Google started launching that stuff in North America. It is really incredible, and one of the few reasons that I use Google Maps for navigation over here more than Waze...not just because it has more info, like street names, but it just shows more detail.

[sprjus4]

Apologies if this was mentioned previously (I didn't read through all pages), but I found one today in Virginia (I didn't realize they existed in this state at all). The double left turn onto the I-64 west ramp at Exit 91 VA-285 is flashing yellow.

https://maps.app.goo.gl/nNvRx31ETYBy4R8XA?g_st=ic

[jakeroot]

Apologies if this was mentioned previously (I didn't read through all pages), but I found one today in Virginia (I didn't realize they existed in this state at all). The double left turn onto the I-64 west ramp at Exit 91 VA-285 is flashing yellow.

https://maps.app.goo.gl/nNvRx31ETYBy4R8XA?g_st=ic

I think this was shared before, but not in this thread. I had been looking for this location, as someone had shared it a while back. But I hadn't been able to figure out where it was. Thank you for posting it.

[jakeroot]

Here is the triple right turn with permissive phasing in Japan I have referred to before (either here or elsewhere).

I seem to remember it being in Tokyo, but it's actually in Osaka. It was changed from a double permissive turn to triple permissive turn in 2014.

https://goo.gl/maps/1DLwzpMDsrs4mLdF7

edit: for anyone wanting to see more pictures of it, search "天王寺駅ジャンクション" on Google. There is a major metro station beneath.

[ran4sh]

That would never work with American drivers

[jakeroot]

That would never work with American drivers

I'd love to see it tried somewhere, but doubt any engineer has the courage to give it a shot.

The issue in Japan with turning traffic doesn't have anything to do with how many lanes there are, but actually oncoming traffic not stopping even after their light is red. Drivers here really push yellow lights, with many entering on red, even two or three seconds after it has come up. This isn't too big of a deal, as the green arrow comes on at the end, giving you plenty of time to wait a moment before finishing your turn. Still, some drivers really push the lights here far worse than anything I've seen anywhere in the US.

edit: fixed sentence missing words.

[Hobart]

Found another example at Front Street and Chouteau Trafficway in Kansas City, Missouri!

This one's especially interesting... not only does it have double towers of 5, it has double towers of 5 for the far-side supplemental left turn signal (which no other approach has), a doghouse on one leg, and a four-section in permissive operation in another... just weird all around.

https://www.google.com/maps/@39.1307471,-94.5232406,3a,75y,72.83h,97.52t/data=!3m6!1e1!3m4!1sRfQQWgtWVNxpiidgS_D4ZA!2e0!7i16384!8i8192

[jakeroot]

Found another example at Front Street and Chouteau Trafficway in Kansas City, Missouri!

This one's especially interesting... not only does it have double towers of 5, it has double towers of 5 for the far-side supplemental left turn signal (which no other approach has), a doghouse on one leg, and a four-section in permissive operation in another... just weird all around.

https://www.google.com/maps/@39.1307471,-94.5232406,3a,75y,72.83h,97.52t/data=!3m6!1e1!3m4!1sRfQQWgtWVNxpiidgS_D4ZA!2e0!7i16384!8i8192

Great find. That is indeed a very unique setup, with the double supplemental left turn 5-section towers. I think I've seen that once or twice, but that's considering the entirety of the US. Particularly unusual for Missouri and Kansas where left-side supplemental signals aren't particularly common anyways. And the mix of signal displays is very odd! I can only think of one intersection with a mix like that, here in Des Moines, WA.

[Hobart]

I found probably the most scuffed example so far.

https://www.google.com/maps/@29.5575179,-98.5350833,3a,41.3y,157.23h,90.45t/data=!3m7!1e1!3m5!1sgQYsQZIYCibuNSbh6kW8lA!2e0!5s20190701T000000!7i16384!8i8192

This is in San Antonio. They have a doghouse and an FYA right next to each other... with both information placards! How the hell is this supposed to work?

[jakeroot]

I found probably the most scuffed example so far.

https://www.google.com/maps/@29.5575179,-98.5350833,3a,41.3y,157.23h,90.45t/data=!3m7!1e1!3m5!1sgQYsQZIYCibuNSbh6kW8lA!2e0!5s20190701T000000!7i16384!8i8192

This is in San Antonio. They have a doghouse and an FYA right next to each other... with both information placards! How the hell is this supposed to work?

Lost of potential, though! They could have added a flashing yellow arrow to the doghouse, and it could have ended up like this FYA/doghouse combo in MN:

https://goo.gl/maps/y1EVTe4XtsRTUmsX9

https://youtu.be/onyZQcgkMOw

[roadfro]

I found probably the most scuffed example so far.

https://www.google.com/maps/@29.5575179,-98.5350833,3a,41.3y,157.23h,90.45t/data=!3m7!1e1!3m5!1sgQYsQZIYCibuNSbh6kW8lA!2e0!5s20190701T000000!7i16384!8i8192

This is in San Antonio. They have a doghouse and an FYA right next to each other... with both information placards! How the hell is this supposed to work?

Lost of potential, though! They could have added a flashing yellow arrow to the doghouse, and it could have ended up like this FYA/doghouse combo in MN:

https://goo.gl/maps/y1EVTe4XtsRTUmsX9

Jake's example for the combo FYA & 5-section makes sense, given the characteristics of the depicted approach and the opposing approach being relatively minor (commercial center parking access) with likely modest volumes.

I am somewhat intrigued by the situation Hobart posted though. The depicted approach is left-shared left/thru-thru-thru, so that 5-section display over the shared lane is non-compliant. But it looks like the cross street has a wide median–the overall operation along FM 1535 appears to be split phased, and this particular signal appears to be running an overlap, so that gives it a little more leeway. It looks like this situation will disappear soon though, as the most recent Street View appears to be converting this overall intersection into something a bit more akin to a SPUI.

[CovalenceSTU]

Just discovered that Lafayette, LA is filled with permissive double lefts, here's one that uses R/YA/(FYA/GA) signals:


https://goo.gl/maps/VXRyWvzXxmcyig2FA

And another one that uses double doghouses and a 5-section signal on the left:

https://goo.gl/maps/FpAUvRPh6qYyVRGS8

[jakeroot]

Just discovered that Lafayette, LA is filled with permissive double lefts, here's one that uses R/YA/(FYA/GA) signals:
....

Really cool find. I actually had a pin saved on my Google Maps of one of the other double-left FYA signals in Lafayette. They definitely aren't afraid of dual permissive turns.

Couple other oddities in Lafayette: (1) they also are keen on double right turns with yield signs (here and here being examples), and (2) this double left turn has an almost absurd amount of offset, even I'm not sure I would have used a yield there, visibility must be awful for the left-left turn lane.

Edit: forgot to mention, but I really like the supplemental signage used in Lafayette. Really helpful and to-the-point.