Triple "Left Turn Only" Lanes

[tradephoric]

While we are on the subject, here is a proposed triple left turn lane at a Parallel Flow Intersection (PFI) at the US 41 / SR-54 intersection in Land "˜O Lakes, Florida:



For the amount of ROW this intersection would require, my proposal would be to convert it to a Town Center Intersection.  I love TCIs but i understand why they aren't more common (as often times you are trying to convert an existing intersection due to LOS issues, and completely demolishing multiple buildings to fit a TCI doesn't make much financial sense).  For some type of planned city though, i think a TCI would be a great intersection choice.
https://www.youtube.com/watch?v=eFFw8JDObGA

[jakeroot]

If I understand correctly, triple left turns are common in Florida because they have to dedicate most of the signal phase to through traffic? Interesting predicament...which came first, the long crosswalk or all the lanes?

I think I already gave my opinion before, but that PFI intersection proposal is absurd. if you need that many lanes, you need to consider building a freeway. At least that way, there won't be as many lanes to cross as a pedestrian. The Town Center intersection seems like a very reasonable alternative.

FWIW, two of the left turns in that PFI proposal are quadruple lefts. Oh my...

[tradephoric]

If I understand correctly, triple left turns are common in Florida because they have to dedicate most of the signal phase to through traffic? Interesting predicament...which came first, the long crosswalk or all the lanes?

There really is a little chicken and the egg going on here!  I don't know enough about Florida's transportation history to determine how they came up with their standard ROW's.  I know for Detroit in 1924 the Rapid Transit Commission released a report named "Proposed Super-Highway Plan for Greater Detroit" that would largely shape the regions transportation network.   In the plan they proposed 204 ft ROW for major arterials in the region.  It was determined 120 feet was the minimum ROW needed for 8-lanes of express vehicular traffic (including sidewalks) and an additional 84 feet of central space was needed for rapid transit lines (120+84=204).  With such wide boulevards pedestrians would cross each direction of the Super-Highway separately (almost treating them as two one-way streets).  Ultimately, even with extremely wide boulevards, Detroit has relatively short pedestrian crossings which helps reduce required cycle lengths and left turn bay queue lengths.  It's the total opposite for Florida. 

[hotdogPi]

In the Boston area, these roads would be a single lane in each direction, resulting in shorter signal cycle lengths but much less capacity. And of course, no grid.

[Rothman]

I am thinking Salt Lake City could match Orlando.

[UCFKnights]

Orlando has many wide boulevards throughout the city and probably has the highest concentration of long pedestrian crosswalks in America.  Orlando isn't the only city in America with wide boulevards - Detroit and New Orleans have wider boulevards on average — but Orlando intersections are designed to get pedestrians the entire way across the intersection and don't split them up into two shorter crossings (like you routinely see at wide intersections in Detroit and New Orleans).  Long continuous crosswalks naturally lead to high cycle lengths, as enough time needs to be given to allow pedestrians to cross the street.  The higher the cycle length the more left-turn queuing space is needed to prevent left-turners from backing up into the through lanes.  Long continuous crosswalks throughout Orlando is one of the main reasons why you see so many massive intersections with double and triple-left turn lanes.  Here are all the intersections in Orlando with continuous crosswalks of 140 feet or more.  I doubt you will find another city in America that comes close to this many long continuous crosswalks:

Having lived throughout the state, I'd say generally South Florida (especially Palm Beach County and Broward County) has consistently more larger intersections then Orlando by a large margin. I don't have numbers/stats to back it up, but just from my time in both places thats my memory of it. My understanding is Orlando has a ban on more then 3 thru lanes per direction on at-grade roads with pedestrians, which doesn't exist in South Florida, so you even see some roads where many intersections in a row are 11 lanes across for pedestrians. Orlando its really rare to see more then 9 lanes across (3 straight, 2 left turn, 1 right turn, 3 opposing straight) and most that are more then that ban pedestrian crossings in that direction.

Is there any intersections with as many or more lanes then that Land O Lakes one built? I've never seen any at grade quite that ginormous.

[Joe The Dragon]

that may be a place for an overpass if just to get out needing big storage areas for train backups.

[andrepoiy]

No idea if this was posted already but I was randomly looking at Tuscaloosa AL and I found this triple-left-turn.

Link: https://goo.gl/maps/va1S45PSDtNTAyYt9

[kphoger]

No idea if this was posted already but I was randomly looking at Tuscaloosa AL and I found this triple-left-turn.

Lots of fun there.  Opposing traffic also has a triple left.  And both directions of cross traffic have a double left with option lane.

[bcroadguy]

I recently found this one at a T-interswection in Tsawwassen, BC: https://www.google.com/maps/@49.0329421,-123.090212,3a,42.4y,148.64h,88.61t/data=!3m6!1e1!3m4!1sEiDvLekAEIODH5_fYiEFxg!2e0!7i16384!8i8192?entry=ttu.

I think this the minor road here will probably be extended in the future, but for now there is a triple left turn.

[kurumi]

Here's a triple U-turn in Seremban 2, Negeri Sembilan, Malaysia: https://maps.app.goo.gl/BYPMBzAT8SyrctEH8

Persiaran Utama S2/3 is a 6-lane boulevard with one interchange, another wide intersection that could be expanded into one, and a dead-end. All 3 lanes do a U-turn.

[Big John]

^^ Looks like triple right turns

[freebrickproductions]

A few more Alabama examples:

US 72 @ Moores Mill Road in Huntsville

Alt. US 72/AL 20 & US 31 in Decatur

There's also this one along US 280 near Birmingham.

[jakeroot]

I recently found this one at a T-interswection in Tsawwassen, BC: https://www.google.com/maps/@49.0329421,-123.090212,3a,42.4y,148.64h,88.61t/data=!3m6!1e1!3m4!1sEiDvLekAEIODH5_fYiEFxg!2e0!7i16384!8i8192?entry=ttu.

I think this the minor road here will probably be extended in the future, but for now there is a triple left turn.

Nice, I've been through there a few times without even realizing what I was looking at. I don't recall many triple lefts in BC.

Any idea where that road would be extended to? Tsawwassen Springs is a private development, and English Bluff seems pretty far off to the south with a golf course in the way.

[cl94]

I see someone revived this thread.

I believe the following is an exhaustive list of current examples in Northern Nevada:

• I-580 SB at South Carson Street in Carson City https://maps.app.goo.gl/Vwua6cCcbJohdaxBA. Officially "temporary" until NDOT gets funding to build an interchange here, the left turn carries the US 395 mainline. The straight movement E-W is the US 50 mainline.
• South Virginia Street SB at South McCarran Blvd (NV 659) in Reno https://maps.app.goo.gl/Cami8WFDmzrUDvw47
• South McCarran Blvd (NV 659) WB at Longley Lane in Reno https://maps.app.goo.gl/tyKLDzyihMRewSU38 . Also includes a left lane drop
• I-80 EB at McCarran Blvd East (NV 659) in Sparks: https://maps.app.goo.gl/tvekgg7S1gkSTJYV6
• I-80 EB at Pyramid Way (NV 445) in Sparks https://maps.app.goo.gl/9Acao719Gcb3i4Dh7
• North McCarran Blvd (NV 659) EB at Pyramid Way (NV 445) in Sparks https://maps.app.goo.gl/jPvABJdgbTnmmMNz5
• I-80 EB at Sparks Blvd in Sparks https://maps.app.goo.gl/3pmqwfjWNnb5FMo8A
• Sparks Blvd NB at Lincoln Way in Sparks https://maps.app.goo.gl/FmVyRf8aYP1ii4Ms9. Despite the name, this is NOT an old alignment of the Lincoln Highway

Northern California has far too many for me to list. The Bay Area and Sacramento are full of triple lefts.

[roadfro]

I believe the following is an exhaustive list of current examples in Northern Nevada:

• I-580 SB at South Carson Street in Carson City [https://maps.app.goo.gl/Vwua6cCcbJohdaxBA]. Officially "temporary" until NDOT gets funding to build an interchange here, the left turn carries the US 395 mainline. The straight movement E-W is the US 50 mainline.
• South Virginia Street SB at South McCarran Blvd (NV 659) in Reno [https://maps.app.goo.gl/Cami8WFDmzrUDvw47]
• South McCarran Blvd (NV 659) WB at Longley Lane in Reno [https://maps.app.goo.gl/tyKLDzyihMRewSU38]. Also includes a left lane drop
• I-80 EB at McCarran Blvd East (NV 659) in Sparks: [https://maps.app.goo.gl/tvekgg7S1gkSTJYV6]
• I-80 EB at Pyramid Way (NV 445) in Sparks [https://maps.app.goo.gl/9Acao719Gcb3i4Dh7]
• North McCarran Blvd (NV 659) EB at Pyramid Way (NV 445) in Sparks [https://maps.app.goo.gl/jPvABJdgbTnmmMNz5]
• I-80 EB at Sparks Blvd in Sparks [https://maps.app.goo.gl/3pmqwfjWNnb5FMo8A]
• Sparks Blvd NB at Lincoln Way in Sparks [https://maps.app.goo.gl/FmVyRf8aYP1ii4Ms9]. Despite the name, this is NOT an old alignment of the Lincoln Highway

I was going to say you forgot one, but after checking I see that it was removed. Formerly, WB Fairview Dr at Carson St had two dedicated left turn lanes and the rightmost lane was a shared left-thru-right, but the left movement has since been removed from the shared lane. I assume that was a temporary setup from when Fairview was Temp US 50/395.

[andrepoiy]

Castle Rock, CO:



Link: https://maps.app.goo.gl/9wZFF5ZBZYk95Xhw8

[JayhawkCO]

For the life of me, I can't find where I posted this before, but it was in a similar thread. And I know it's mentioned above, but I-225 NB to Parker Road (CO83) here in Aurora now has 3 lefts and 4 rights.