Double left turns with permissive phasing

Started by jakeroot, December 14, 2015, 02:01:17 AM

Previous topic - Next topic

Do you think dual permissive turns should be allowed?

Yes
57 (50.4%)
No
35 (31%)
Cat
21 (18.6%)

Total Members Voted: 113

jakeroot

Quote from: MCRoads on April 06, 2018, 12:15:14 PM
Found one!!!

Academy and Carefree in Colorado Springs!!!

http://i.imgur.com/yeD1X4J.jpg

No surprise really. Colorado has used dual permissive phasing all across the state for quite a while now. Here's three more examples from Colorado Springs (that I knew of previously -- these are in addition to literally hundred+ other examples in the metro Denver area). Click the photos for Street View. The double-doghouse was the standard setup (usually with a tower on the left-most mast arm), but the state has basically switched over to flashing yellow arrows at this point.







Revive 755

#151
Not sure WB 30th Street at South Expressway and the EB I-80/SB I-29 ramps in Council Bluffs, Iowa, has been mentioned yet.  Streetview WB.  Also the first time I believe I have seen both doghouses and a 5-section tower on the same mast arm (for EB).

jakeroot

Quote from: Revive 755 on April 07, 2018, 11:06:43 AM
Not sure WB 30th Street at South Expressway and the EB I-80/SB I-29 ramps in Council Bluffs, Iowa, has been mentioned yet.  Streetview WB.  Also the first time I believe I have seen both doghouses and a 5-section tower on the same mast arm (for EB).

Wait, which approach has the double permissive left? I see a double doghouse, but it looks like it's for when a train is approaching, and the off-ramp's center lane turns into a right turn lane (hence the double 5-section signals with right-facing arrows.

Doghouse and tower signals on the same mast arm are indeed quite rare. I've only seen it once before in Auburn, WA, and it's since been removed.

MNHighwayMan

Maybe/maybe not there, but there is definitely a pair of them in West Des Moines at the reconstructed Grand Avenue interchange with I-35. This is the one for EB Grand to turn onto NB I-35:




jakeroot

Quote from: MNHighwayMan on April 07, 2018, 06:52:24 PM
Maybe/maybe not there, but there is definitely a pair of them in West Des Moines at the reconstructed Grand Avenue interchange with I-35. This is the one for EB Grand to turn onto NB I-35:

Satellite imagery from October shows only one left turn lane from Grand Ave to both north and south 35W. I'm guessing things have been modified since then? There's clearly room for another turn lane.

MNHighwayMan

#155
Yep. Those pictures are from January 30, 2018. I'm not sure, since I don't go over that way too often, but I think the work was done not long after that aerial imagery was taken.

Revive 755

#156
Quote from: jakeroot on April 07, 2018, 02:25:35 PM
Quote from: Revive 755 on April 07, 2018, 11:06:43 AM
Not sure WB 30th Street at South Expressway and the EB I-80/SB I-29 ramps in Council Bluffs, Iowa, has been mentioned yet.  Streetview WB.  Also the first time I believe I have seen both doghouses and a 5-section tower on the same mast arm (for EB).

Wait, which approach has the double permissive left? I see a double doghouse, but it looks like it's for when a train is approaching, and the off-ramp's center lane turns into a right turn lane (hence the double 5-section signals with right-facing arrows.

I thought WB 30th Street (the east leg did), but it appears I misinterpreted the signing on the mast arm - the middle sign should be an R3-5 with only a straight ahead arrow.  Guess I've been corrupted lately by seeing too many option lane signs with 'only' on them and also seeing many intersections having signal heads not match intended lane usage.

jakeroot

Quote from: Revive 755 on April 08, 2018, 07:56:18 PM
Quote from: jakeroot on April 07, 2018, 02:25:35 PM
Quote from: Revive 755 on April 07, 2018, 11:06:43 AM
Not sure WB 30th Street at South Expressway and the EB I-80/SB I-29 ramps in Council Bluffs, Iowa, has been mentioned yet.  Streetview WB.  Also the first time I believe I have seen both doghouses and a 5-section tower on the same mast arm (for EB).

Wait, which approach has the double permissive left? I see a double doghouse, but it looks like it's for when a train is approaching, and the off-ramp's center lane turns into a right turn lane (hence the double 5-section signals with right-facing arrows.

I thought WB 30th Street (the east leg did), but it appears I misinterpreted the signing on the mast arm - the middle sign should be an R3-5 with only a straight ahead arrow.  Guess I've been corrupted lately by seeing too many option lane signs with 'only' on them and also seeing many intersections having signal heads not match intended lane usage.

I noticed that signing irregularity when you first posted the intersection (and I spent several minutes scanning the ground to confirm that it was accurate, which I was not able to). Indeed quite misleading. Typically you don't see lane use signs and specific lane control signs on the same arm. Totally understandable misinterpretation.

jakeroot

Edmonton, Alberta used to have a bunch of double permissive left turns, but many have disappeared. They have actually become quite hard to find. Far cry from the days of the city actually being known by engineers outside the city just for these. Now, there seems to only be a handful left.

One that I went through a couple of times when I was last there has been changed to protected-only. Odd that they didn't try to improve safety by implementing a short protected phase, but it's irrelevant now. What I did find funny was, that, after reviewing Street View footage, I noticed that the original left turn, circa 2009, was a single permissive-only left turn. In 2009, Stony Plain Road was widened significantly, and double left turns were included for the east and west approaches. Despite the additional left turn lane for each approach, permissive-only phasing was kept. The vast majority of double permissive turns, regardless of location (or country), seem to have some sort of protected phase (otherwise, a protected-permissive single lane approach would have probably worked well too). Seattle has a few of these, but for the most part, it's pretty damn unusual. Especially unusual in this case because the road was so new.

Typically, when a city widens a road or adds an additional left turn lane, it's due to either current or future volume. Either way, you typically see the phasing changed to either protected-permissive or protected only. But, I guess the traffic counts were still so low, they kept the permissive only phasing for these left turns.

2012 GSV, before protected-only phasing: https://goo.gl/2iMzti

2009...


2010/2011 (until ~2016)...

Roadwarriors79

@Jakeroot, this link is for you. As of June 2018, Broadway Blvd and Aviation Hwy (AZ 210) in Tucson STILL has permissive dual left turns at this half-SPUI:


https://www.google.com/maps/@32.2210231,-110.9618543,3a,75y,244.05h,87.64t/data=!3m6!1e1!3m4!1sIQYZESMK6u1M-ZZVjMUiuA!2e0!7i13312!8i6656

jakeroot

Quote from: Roadwarriors79 on October 21, 2018, 12:20:37 PM
@Jakeroot, this link is for you. As of June 2018, Broadway Blvd and Aviation Hwy (AZ 210) in Tucson STILL has permissive dual left turns at this half-SPUI:


https://www.google.com/maps/@32.2210231,-110.9618543,3a,75y,244.05h,87.64t/data=!3m6!1e1!3m4!1sIQYZESMK6u1M-ZZVjMUiuA!2e0!7i13312!8i6656

Great to see. It's a good place for a permissive turn, not having any oncoming traffic.

Roadwarriors79

Quote from: jakeroot on October 21, 2018, 01:12:17 PM
Quote from: Roadwarriors79 on October 21, 2018, 12:20:37 PM
@Jakeroot, this link is for you. As of June 2018, Broadway Blvd and Aviation Hwy (AZ 210) in Tucson STILL has permissive dual left turns at this half-SPUI:


https://www.google.com/maps/@32.2210231,-110.9618543,3a,75y,244.05h,87.64t/data=!3m6!1e1!3m4!1sIQYZESMK6u1M-ZZVjMUiuA!2e0!7i13312!8i6656

Great to see. It's a good place for a permissive turn, not having any oncoming traffic.

What about the traffic going EB on Broadway? It's weird to me because every other SPUI or half-SPUI I have seen has had protected left signals in all directions. Even in Tucson.

jakeroot

Quote from: Roadwarriors79 on October 21, 2018, 02:59:41 PM
Quote from: jakeroot on October 21, 2018, 01:12:17 PM
Quote from: Roadwarriors79 on October 21, 2018, 12:20:37 PM
@Jakeroot, this link is for you. As of June 2018, Broadway Blvd and Aviation Hwy (AZ 210) in Tucson STILL has permissive dual left turns at this half-SPUI:


https://www.google.com/maps/@32.2210231,-110.9618543,3a,75y,244.05h,87.64t/data=!3m6!1e1!3m4!1sIQYZESMK6u1M-ZZVjMUiuA!2e0!7i13312!8i6656

Great to see. It's a good place for a permissive turn, not having any oncoming traffic.

What about the traffic going EB on Broadway? It's weird to me because every other SPUI or half-SPUI I have seen has had protected left signals in all directions. Even in Tucson.

When I said oncoming traffic, I meant no oncoming *left turn. My bad. Visibility is good for turning traffic so I don't feel there is too much of an issue. Most SPUIs use protected phasing because the distance between the stop line and exit leg is so great, you'd need like a 7 second all red phase to clear traffic. But since lagging turns are used here, that's not a big worry.


jakeroot

#164
Quote from: bcroadguy on November 15, 2018, 04:09:23 AM
I found one in Richmond, BC:

https://www.google.com/maps/@49.170125,-123.1592228,3a,41y,84.91h,88.83t/data=!3m6!1e1!3m4!1szDZOotchBd0mtzZX2Ngj-w!2e0!7i16384!8i8192

Oh shit, nice find! Cannot believe I didn't know about that one. Your drive through there often?

That now brings BC's total back to four. The other three are Cambie at Marine Drive, Denman at West Georgia, and Main at the Dunsmuir Viaduct. Pacific at Burrard once had it until removal a short time ago. The Richmond example, though, is the coolest so far as it doesn't involve option lanes.

Edit: you know you're in Richmond when a Lambo just casually strolls through: https://goo.gl/vPed2y

bcroadguy

Nah, I almost never go to Richmond. I just happened to find it on Streetview today. I knew about the Main Street one but I never noticed the double left turns at Denman & West Georgia and Cambie & Marine before. There is another one in Vancouver somewhere (with an option lane unfortunately), but I'm not sure exactly which intersection. I'll post when I find it.

Edit: Lol classic Richmond

jakeroot

Quote from: bcroadguy on November 15, 2018, 04:34:03 AM
There is another one in Vancouver somewhere (with an option lane unfortunately), but I'm not sure exactly which intersection. I'll post when I find it.

Now that you mention it, I do feel like I'm missing something from that list. Are you thinking somewhere downtown, or outside downtown but within city limits? Never would have guessed that anyone besides the City of Vancouver would have the balls to install a double permissive left, but Richmond clearly has proved me wrong. I usually focus my search for these things in urban areas, but there could be some in suburban areas too.


jakeroot

#168
Quote from: bcroadguy on November 15, 2018, 04:51:28 AM
Found it!

https://www.google.com/maps/@49.2578379,-123.1843362,3a,75y,84.23h,87.65t/data=!3m7!1e1!3m5!1sTZSRt0P3pMAvMerqOdhHZg!2e0!5s20170501T000000!7i13312!8i6656

https://www.google.com/maps/@49.2579849,-123.1840422,3a,23.3y,60.57h,88.97t/data=!3m7!1e1!3m5!1sm2Wy0W5ygSDGhSaDpL7YrA!2e0!5s20170501T000000!7i13312!8i6656 (Walk signal on)

Oh nice! Did not know about that one, though I rarely venture out towards UBC.

Quote from: bcroadguy on November 15, 2018, 04:51:28 AM
Other than that Richmond example, the closest thing I've seen in the suburbs is this double left turn where you have to yield to pedestrians:
https://www.google.com/maps/@49.2835933,-122.8234701,3a,75y,111.39h,88.31t/data=!3m7!1e1!3m5!1sBq7KlviEkYO7cVUdphSzWA!2e0!5s20160601T000000!7i13312!8i6656

Still relatively unusual, especially for suburban cities.

Quote from: bcroadguy on November 15, 2018, 04:51:28 AM
Edit: Juuuuust found this right near the example I posted. I think Richmond's probably your best bet for finding more of these:
https://www.google.com/maps/@49.1799028,-123.1538032,3a,49y,118.23h,85.93t/data=!3m7!1e1!3m5!1sbGEzFf5ezPkHiQewxF42mA!2e0!5s20160601T000000!7i13312!8i6656

God, another one I should have known about. Apparently Richmond is pretty easy-going! Cool to see those guide lines out in the intersection to keep drivers from pulling too far forward when yielding. Normally that's not an issue but it could unintentionally block a left turner if a driver places their vehicle in the wrong place. The Denman intersection could use this (for both directions instead of just one).

I guess this is the only proper 24/7 option lane double left (with permissive phasing), as, though it permits it most of the time, the Denman/West Georgia intersection does not allow straight-ahead movements between 3 & 7pm.

jakeroot

#169
Christmas came early for me this year! I have been looking for a double permissive left turn in Oregon for god knows how long, and I've yet to find anything...until today. And boy, did I hit the jackpot.

In Springfield, the intersection of Martin Luther King Jr Parkway and Cardinal Way has dual permissive lefts for three of the four approaches (the fourth is a single-lane FYA):

Spin around for proof: http://bit.ly/2PLKKVu
Note the oncoming traffic sailing through the intersection, and the blank signals: http://bit.ly/2EsBh38

The lefts from Cardinal Way aren't particularly well designed, but hey, it must be the only one in Oregon, so it gets brownie points for uniqueness! I can't find a single thread of evidence online announcing this change (the phasing is new for 2018, judging by historic Street View), so it must be a test or something.

Oregon has several FYAs where a single lane approach has permissive phasing, opposite a double left with protected phasing, something I don't see too often in WA (only a couple installs that I know of), but I never would have guessed that any agency in Oregon would install dual FYAs. Sort of out-of-character, I guess.


roadfro

I am pretty sure I have previously asserted that Nevada does not do double permitted left turns. Today I have discovered one in the wild, and a FYA at that. It's southbound Old Virginia Road at Damonte Ranch Pkwy in south Reno. (Street view: https://goo.gl/maps/Ffnykm9Dhww) This is a part of town that I don't frequent, so am not overly familiar with the intersection dynamics–I went through tonight well after pm peak on a green arrow.

So my previous assertion was incorrect, but it's still mostly correct.
Roadfro - AARoads Pacific Southwest moderator since 2010, Nevada roadgeek since 1983.

Amtrakprod

Quote from: roadfro on December 20, 2018, 02:11:16 AM
I am pretty sure I have previously asserted that Nevada does not do double permitted left turns. Today I have discovered one in the wild, and a FYA at that. It's southbound Old Virginia Road at Damonte Ranch Pkwy in south Reno. (Street view: https://goo.gl/maps/Ffnykm9Dhww) This is a part of town that I don't frequent, so am not overly familiar with the intersection dynamics–I went through tonight well after pm peak on a green arrow.

So my previous assertion was incorrect, but it's still mostly correct.
Very interesting, glad to see the FYA is set up correctly as well


iPhone
Roadgeek, railfan, and crossing signal fan. From Massachusetts, and in high school. Youtube is my website link. Loves FYAs signals. Interest in Bicycle Infrastructure. Owns one Leotech Pedestrian Signal, and a Safetran Type 1 E bell.

jakeroot

#172
Quote from: roadfro on December 20, 2018, 02:11:16 AM
So my previous assertion was incorrect, but it's still mostly correct.

I think it's best we divide cities/states/countries into two categories: formal (2+ installs), or informal (only 1 install). Places that would qualify for the "formal" category include...

* Edmonton (AB)
* Tucson & Chandler (AZ) (latter by time-of-day only)
* Kennewick & Seattle (WA)
* Huntsville (AL)
* Vancouver (BC)
* New York City
* Colorado
* North Carolina
* Texas
* Mississippi
* Minnesota (by time-of-day?)
* South Africa
* Singapore
* Japan
* Denmark

* It should be mentioned that in Washington, Oregon, Michigan, and British Columbia, drivers may turn left onto a one-way street even when there is two or more left turn lanes, on a red light or red arrow (ID excluded since turns on red arrows are not permitted there, eliminating double lefts). In this sense, these four areas technically sanction dual permissive left turns for all on-ramps with two or more left turn lanes, though a stop is required first.

Some places with what I consider to be "informal" usage (only one install) include:

* Cupertino (only briefly)
* Idaho (fairly new install in Coeur d'Alene)
* Reno
* Chicago
* Springfield (OR)
* Eau Claire (WI)
* Albuquerque
* Virginia
* Maryland
* Red Deer (AB)
* Regina (SK)

and probably a few more places that I've neglected to remember at this time. Some places like St Louis and other parts of Illinois previously had dual permissive left turns, but they've been removed. Chicago is now alone in the "informal" category, and Missouri no longer has any that I know of. Las Vegas had one, but it was removed, keeping Nevada off the formal list, and placing Reno alone in the informal list.

jakeroot

Quote from: Revive 755 on September 29, 2017, 10:01:11 PM
Found a protected-permissive dual left in Ankeny, Iowa for US 69/Ankeny Boulvard at 1st Street that uses two five-section towers:  Streetview

The Des Moines newspaper though indicates this will be changed to a single left.  http://www.desmoinesregister.com/story/news/local/ankeny/2017/09/29/ankeny-boulevard-and-1st-street-improvements-coming-2020/718133001/
Quote from: MNHighwayMan on September 29, 2017, 11:56:48 PM
Having been through that intersection a few times, yeah, it can be a bit hairy. I never understood the reason for there being two left turn lanes onto SB US-69 (Ankeny Blvd).

From this 2018/August Street View image, it appears the intersection is now operating with single left turns: http://bit.ly/2T7xoVp


MNHighwayMan

That might just be temporary for minor road repair, because that linked article stated that it was going to be a couple years before they removed it. I'll have to go check it out when I'm not tipsy from Christmas. ;-)



Opinions expressed here on belong solely to the poster and do not represent or reflect the opinions or beliefs of AARoads, its creators and/or associates.