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National Boards => General Highway Talk => Traffic Control => Topic started by: roadman65 on August 14, 2023, 05:11:47 PM

Title: Continuous Flow Green T Intersections
Post by: roadman65 on August 14, 2023, 05:11:47 PM
How common are they?

I know NJ used them in Essex County at some of its mall entrances. Though in shopping centers some would use left side driving to avoid a third signal phase and eliminate left turn yielding.

Livingston Mall in Livingston, NJ and Brunswick Square in East Brunswick, NJ have a left side mall entrance but use jughandles at those entrances/ exits so all parties must experience a stop cycle thus not being continuous on the third leg.

In Lakeland, FL where I live, we have one on US 92 and Reynolds Road. WB US 92 never stops there as NB Reynolds has a median merge lane built in to WB US 92.
Title: Re: Continuous Flow Green T Intersections
Post by: chrisg69911 on August 14, 2023, 10:36:12 PM
Quote from: roadman65 on August 14, 2023, 05:11:47 PM
How common are they?

I know NJ used them in Essex County at some of its mall entrances. Though in shopping centers some would use left side driving to avoid a third signal phase and eliminate left turn yielding.

Livingston Mall in Livingston, NJ and Brunswick Square in East Brunswick, NJ have a left side mall entrance but use jughandles at those entrances/ exits so all parties must experience a stop cycle thus not being continuous on the third leg.

In Lakeland, FL where I live, we have one on US 92 and Reynolds Road. WB US 92 never stops there as NB Reynolds has a median merge lane built in to WB US 92.

Don't really know if this counts, but anywhere there is a one-way going away from the intersection, like this

https://maps.app.goo.gl/z63QhwXxjwUCHUTt6
Title: Re: Continuous Flow Green T Intersections
Post by: andrepoiy on August 15, 2023, 10:21:45 PM
In Ontario, probably not that common.

There's only two I can think of off the top of my head:

Vaughan, ON:

(https://i.imgur.com/OB02zGc.png)

https://goo.gl/maps/p2PkygPS1cXPmKdX8

and

Pickering, ON:

(https://i.imgur.com/9KfxH66.png)

https://goo.gl/maps/PM2MHAZ7i4tpZ9Wo9
Title: Re: Continuous Flow Green T Intersections
Post by: gonealookin on August 15, 2023, 11:00:16 PM
Three in a row on US 395 in Carson Valley, Nevada, south of Carson City.

US 395 at Stephanie Way:
https://goo.gl/maps/PsSKrQRTvATp7vbG8 (https://goo.gl/maps/PsSKrQRTvATp7vbG8)

US 395 at Johnson Lane:
https://goo.gl/maps/MY3mPQCAp1ABEQpU6 (https://goo.gl/maps/MY3mPQCAp1ABEQpU6)

US 395 at (Minden) Airport Road (this one was installed just a few years ago; there used to be a stop sign on Airport Road):
https://goo.gl/maps/6APS6oQb6rAWLcFL7 (https://goo.gl/maps/6APS6oQb6rAWLcFL7)

It's about 3 miles down that stretch of US 395.
Title: Re: Continuous Flow Green T Intersections
Post by: steviep24 on August 17, 2023, 06:34:16 AM
NY 31 at the entrance to Whole Foods in Rochester/Pittsford, NY. Only one I know of in the Rochester, NY area.

https://www.google.com/maps/@43.1131502,-77.5505011,3a,75y,151.54h,90t/data=!3m6!1e1!3m4!1sMHxLzy53niePTY8McpEV9w!2e0!7i16384!8i8192?hl=en&authuser=0&entry=ttu

NOTE: This one may not be a true continuous flow t intersection since that exit for Whole Foods is right turn only.
Title: Re: Continuous Flow Green T Intersections
Post by: US 89 on August 17, 2023, 08:25:45 AM
These are pretty common in Nevada and Utah, where they are apparently known as "High-T"  intersections (though I've never seen this term actually used). They're also called seagull intersections (https://en.m.wikipedia.org/wiki/Seagull_intersection) because the traffic Island between the left turns and the continuous green direction looks like a seagull when you're looking up the T.

Could swear we've had a thread on these before. The entrance to Arches NP from US 191 is a well known example. They don't even have to be signalized, like the US 89/SR 12 intersection southeast of Panguitch, UT.
Title: Re: Continuous Flow Green T Intersections
Post by: TEG24601 on August 17, 2023, 12:14:35 PM
Washington likes to use them.


SR 20 and SR 20 Spur in Anacortes used to be one, but was replaced with a roundabout.


I've seen several others, but cannot recall them off of the top of my head, but I suspect one of our other learnéd member would recall some of them.
Title: Re: Continuous Flow Green T Intersections
Post by: roadfro on August 20, 2023, 06:17:42 PM
Quote from: US 89 on August 17, 2023, 08:25:45 AM
These are pretty common in Nevada and Utah, where they are apparently known as "High-T"  intersections (though I've never seen this term actually used).

City of Las Vegas actually used the term on a few warning signs (https://goo.gl/maps/PjHYm6TyAfnCk5mG9) (spelled "Hi") for the three or four of these installed along eastbound W Cheyenne Ave. But aside from that, the phrase is primarily used by engineers and not the general public (at least in Nevada).
Title: Re: Continuous Flow Green T Intersections
Post by: ilpt4u on August 20, 2023, 07:09:42 PM
Didn't these used to be called "Seagull"  intersections?

There is one that freeflows EB and one that freeflows WB just west of Marion on IL 13
EB: https://maps.app.goo.gl/U6EzPgeokutMiTWM9?g_st=ic
WB: https://maps.app.goo.gl/tCEzh7n9P5feJz9r8?g_st=ic

Another I know of in East Peoria on US 24/150/IL 116: https://maps.app.goo.gl/HpJdDVcwa6dDcEHE8?g_st=ic

Quote from: US 89 on August 17, 2023, 08:25:45 AM
These are pretty common in Nevada and Utah, where they are apparently known as "High-T"  intersections (though I've never seen this term actually used). They're also called seagull intersections (https://en.m.wikipedia.org/wiki/Seagull_intersection) because the traffic Island between the left turns and the continuous green direction looks like a seagull when you're looking up the T.

Could swear we've had a thread on these before. The entrance to Arches NP from US 191 is a well known example. They don't even have to be signalized, like the US 89/SR 12 intersection southeast of Panguitch, UT.
I didn't find a dedicated thread yet, but there are 10 other thread hits other than this one for "seagull intersection"

*EDIT* Found the older thread where these were discussed, on the "Road Related Illustrations"  board: https://www.aaroads.com/forum/index.php?topic=27562

Honestly, the this thread and the older thread could be merged, but I would think here in Traffic Control is better than Road Related Illustrations. Or keep separate. We have good Mods here  :clap:
Title: Re: Continuous Flow Green T Intersections
Post by: CoreySamson on August 20, 2023, 09:16:22 PM
The only Texas example I know of is this one near Texarkana:
https://goo.gl/maps/7EXvLxCjEc75GE4b8
Title: Re: Continuous Flow Green T Intersections
Post by: jeffandnicole on August 20, 2023, 11:09:58 PM
A few NJ Examples: 

Brigantine Connector at Brigantine Blvd (NJ 187) in Atlantic City:  https://goo.gl/maps/YYc9GqnciJTKJGYo8

CR 547 at the entrance to Joint Base MDL in Manchester Twp: https://goo.gl/maps/aXjcjCvHtPfMeE8C7

A NJTA variation at Exit 0 of the Garden State Parkway Northbound, where instead of using a standard seagull intersection, they incorporated a jughandle into it: https://goo.gl/maps/oEq8Yo6ZqJaApTUR9 ; https://goo.gl/maps/Nt8NM33JagHEoqGa7
Title: Re: Continuous Flow Green T Intersections
Post by: TXtoNJ on August 21, 2023, 01:18:43 AM
Quote from: CoreySamson on August 20, 2023, 09:16:22 PM
The only Texas example I know of is this one near Texarkana:
https://goo.gl/maps/7EXvLxCjEc75GE4b8

https://goo.gl/maps/xeRrWYGvxCz9wnhV9
Title: Re: Continuous Flow Green T Intersections
Post by: ilpt4u on August 21, 2023, 07:59:51 AM
Quote from: TXtoNJ on August 21, 2023, 01:18:43 AM
Quote from: CoreySamson on August 20, 2023, 09:16:22 PM
The only Texas example I know of is this one near Texarkana:
https://goo.gl/maps/7EXvLxCjEc75GE4b8

https://goo.gl/maps/xeRrWYGvxCz9wnhV9
The older thread had an El Paso example:
Quote from: PurdueBill on September 27, 2020, 05:00:55 PM
My favorite one of these that I have driven through in all directions myself is Executive Center Blvd. at US 85 in El Paso, Texas, probably because of all the railroad trestles and a grade crossing just past the intersection on Exec Ctr., but especially because one lane of 85 SB goes with the left turn lane for some reason instead of bypassing, getting stop and go, and the bypass lane gets a single 3M green straight ahead arrow signal.  Also a changeable message sign in turning parts facing Executive Center traffic.  Total craziness and I love it.

https://goo.gl/maps/6jp6J3GTpVSRVqUU9
Title: Re: Continuous Flow Green T Intersections
Post by: fwydriver405 on August 25, 2023, 03:46:30 PM
Unsure if this counts, but at Beacon St at Grant Rd (https://www.google.com/maps/@42.3310439,-71.1885504,3a,88.7y,79.2h,79.98t/data=!3m8!1e1!3m6!1sZ4bSxNcGxZ2kbAPRd8kJCw!2e0!5s20221001T000000!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fpanoid%3DZ4bSxNcGxZ2kbAPRd8kJCw%26cb_client%3Dsearch.revgeo_and_fetch.gps%26w%3D96%26h%3D64%26yaw%3D72.6592%26pitch%3D0%26thumbfov%3D100!7i16384!8i8192?entry=ttu) in Newton, MA, the Continuous Green T is for eastbound thru cyclists only in the cycle lane on Beacon St - the signal remains green for all phases except for the exclusive pedestrian phase (9) where it changes.

https://www.youtube.com/watch?v=2Ew8M-Pskr8

There's also this setup at MA Route 16 at South Ferry St (https://www.google.com/maps/@42.402668,-71.0501544,3a,15y,84.77h,89.97t/data=!3m6!1e1!3m4!1sJTjlY1COecmPlt9tRqWC6A!2e0!7i16384!8i8192?entry=ttu) in Everett - the left and U-turns are signalised, but the eastbound thru traffic is continous. Although Mass law allows a left turn on red from a one way to another one way (steady circular or steady red arrow), I'm not sure if U-turns count for that left turn on red movement here.

In New Hampshire, at US 4 at NH Route 16 South (https://www.google.com/maps/@43.1291254,-70.8408441,3a,31.2y,24.1h,91.36t/data=!3m6!1e1!3m4!1sRs3rBGySijY4t2w8cTHdMA!2e0!7i16384!8i8192?entry=ttu), the westbound US 4 approach is technically a Continuous Green T since there currently is no conflicting phases to make the westbound thru direction have to stop at all.

In Maine, the left turn from SB Maine Route 77 to Erkine Drive (https://www.google.com/maps/@43.6365192,-70.2586594,3a,75y,122.01h,80.48t/data=!3m7!1e1!3m5!1sfXl4NjC_p5Z_CBoQ_Tgb_w!2e0!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fpanoid%3DfXl4NjC_p5Z_CBoQ_Tgb_w%26cb_client%3Dsearch.revgeo_and_fetch.gps%26w%3D96%26h%3D64%26yaw%3D20.736471%26pitch%3D0%26thumbfov%3D100!7i16384!8i8192?entry=ttu) in South Portland is very similar to the Everett example.

I also saw one in Québec on Autoroute 740 south (https://www.google.com/maps/@46.7791509,-71.2811255,3a,31.7y,163.96h,85.92t/data=!3m6!1e1!3m4!1sw5U3rIN94OpJUCDlu4sYGg!2e0!7i16384!8i8192?entry=ttu), however this fully protected left turn is restricted to buses only.

EDIT:

Two more in Massachusetts:

Billerica, MA: MA Route 3 at River St (YoG - pm+pt) (https://www.google.com/maps/@42.5599947,-71.2693327,3a,80.3y,347.31h,80.19t/data=!3m7!1e1!3m5!1sw30vR7V2s8AVA0D0K95xrg!2e0!5s20210901T000000!7i16384!8i8192?entry=ttu) - the 5-section doghouse used to be a 3-section signal (CG-YA-GA), similar to this bi-modal setup in Vancouver, British Columbia (https://www.google.com/maps/@49.2904013,-123.1302711,3a,31.3y,139.36h,87.78t/data=!3m6!1e1!3m4!1s3k1Br9gQ0b9iwg5NFJ-LDA!2e0!7i16384!8i8192?entry=ttu)

Haverhill, MA: MA Route 125 at Industrual Ave (https://www.google.com/maps/@42.7497389,-71.1083583,3a,33y,2.32h,86.98t/data=!3m6!1e1!3m4!1sdrnOFK9ZcERiXnH2D9KQ1A!2e0!7i16384!8i8192?entry=ttu)
Title: Re: Continuous Flow Green T Intersections
Post by: bcroadguy on October 01, 2023, 06:38:53 AM
This one in Seattle is kind of interesting: https://www.google.com/maps/@47.569174,-122.3133607,3a,57.5y,350.05h,95.96t/data=!3m6!1e1!3m4!1sUCStWzKC5L6d2mgmDpjQTg!2e0!7i16384!8i8192?hl=en&entry=ttu.

The through lanes face no hazard, yet see a flashing yellow ball instead of the typical green straight arrow.
Title: Re: Continuous Flow Green T Intersections
Post by: bcroadguy on October 01, 2023, 06:51:13 AM
Cities in BC don't like these that much, but BC Ministry of Transportation LOOOOOOVES using this type of intersection on 4-lane divided expressways. There are a decent number of signalized "protected T intersections" (such as this one: https://www.google.com/maps/@49.2131887,-122.8031403,3a,39.1y,99.81h,91.27t/data=!3m6!1e1!3m4!1swbANtHL4wTulr1A_jDO-Og!2e0!7i16384!8i8192?entry=ttu) but there are a LOT of new unsignalized ones in rural areas lately: https://www.google.com/maps/@50.646354,-119.9034103,3a,75y,20.4h,81.58t/data=!3m6!1e1!3m4!1sxE3QoGPczPiyW5s7eap8mw!2e0!7i16384!8i8192?entry=ttu.
Title: Re: Continuous Flow Green T Intersections
Post by: LilianaUwU on October 01, 2023, 06:52:56 AM
Quote from: fwydriver405 on August 25, 2023, 03:46:30 PM
I also saw one in Québec on Autoroute 740 south (https://www.google.com/maps/@46.7791509,-71.2811255,3a,31.7y,163.96h,85.92t/data=!3m6!1e1!3m4!1sw5U3rIN94OpJUCDlu4sYGg!2e0!7i16384!8i8192?entry=ttu), however this fully protected left turn is restricted to buses only.

Nope, this is just a regular traffic light. I would know, I went through that one multiple times.
Title: Re: Continuous Flow Green T Intersections
Post by: freebrickproductions on October 01, 2023, 04:00:02 PM
There's one in use here in Huntsville, AL, on Meridian Street.
https://www.google.com/maps/@34.7608179,-86.5755383,3a,52.6y,51.85h,98.66t/data=!3m6!1e1!3m4!1s883Nu8WNIvt7ia69E_Co4A!2e0!7i16384!8i8192?entry=ttu

For the variant where the side road can only turn right, then I suppose this one on US 280 near Birmingham also qualifies:
https://www.google.com/maps/@33.4647978,-86.7572807,3a,75y,157.95h,91.19t/data=!3m6!1e1!3m4!1s6-J4oTk-fmz-m-SJt6r2Ag!2e0!7i16384!8i8192?entry=ttu
As a side note, that intersection is also the reason why ALDOT adopted the FYA signal when they did, apparently, as it was the first FYA signal to be installed on a road ALDOT is in charge of.

EDIT: Just remembered, US 280 has a full one here:
https://www.google.com/maps/@33.4372063,-86.7217591,3a,75y,295.87h,99.38t/data=!3m6!1e1!3m4!1sYXxypnTKQpi1NmVyheERGQ!2e0!7i16384!8i8192?entry=ttu

Also, would this (https://www.google.com/maps/@33.4711196,-86.7619402,3a,75y,107.1h,100.26t/data=!3m6!1e1!3m4!1sVYmPfOIeG__KBC1A1bfx3w!2e0!7i16384!8i8192?entry=ttu) count as a continuous green 4-way intersection?