There's one in the STL area (55 at Linbergh, north of the 270 interchange) that dates to the mid 90s, according to Google Earth historical imagery. Anyone else know of any old SPUIs?
There is a very old one in Ft Worth TX at SH 180 (Former US 80) (Lancaster Av) at Beach St
https://www.google.com/maps/@32.7438201,-97.2894799,362m/data=!3m1!1e3 (https://www.google.com/maps/@32.7438201,-97.2894799,362m/data=!3m1!1e3)
NE2 might be one of the oldest, don't know when he was born.
Quote from: Roadgeekteen on May 19, 2020, 08:42:20 PM
NE2 might be one of the oldest, don't know when he was born.
Nope. According to his profile he's only 12. :D
Quote from: TheHighwayMan394 on May 19, 2020, 08:45:29 PM
Quote from: Roadgeekteen on May 19, 2020, 08:42:20 PM
NE2 might be one of the oldest, don't know when he was born.
Nope. According to his profile he's only 12. :D
Most political and profane 12yo I've ever met then.
In Denver, Colorado, the SPUI at Santa Fe Dr (US 85) and Evans Ave (map (https://www.google.com/maps/@?api=1&map_action=map¢er=39.678426,-104.993512&zoom=16&basemap=satellite)) seems to have been put in sometime between 1983 and 1986, going by this report (http://digital.auraria.edu/AA00000079/00001) and CDOT's inventory. The viaduct that takes Evans over Santa Fe and the railroad was reportedly build in 1972 by Denver, and CDOT added the ramps later; Denver still owns the viaduct, and CDOT owns the ramps.
I'd wondered before if the ramps looked weird because there had been a regular diamond there before, and I was surprised to see that there just wasn't direct access between Santa Fe and Evans for a while. USGS has an aerial photo of the area from 1978 that shows the viaduct without ramps, but it requires an account (here (https://earthexplorer.usgs.gov/download/options/4660/AR1VEQP00010141)).
In Colorado Springs, the SPUI at I-25 and Garden of the Gods Rd was built in 1988 (map (https://www.google.com/maps/@?api=1&map_action=map¢er=38.896790,-104.830245&zoom=16&basemap=satellite); ROW plans (http://dtdapps.coloradodot.info/row_plans/region2/ROWMaps/SH-25/IR%2025-2(184).pdf)); before the SPUI, there was a regular diamond with separate bridges for northbound and southbound I-25.
Another old one could be C-470 and Morrison Rd (map (https://www.google.com/maps/@?api=1&map_action=map¢er=39.653235,-105.181346&zoom=16&basemap=satellite)); the bridges are from 1989, and I want to say the interchange has only ever been a SPUI.
I-170 at MO 180 is older than I-55 at US 50-61-67, though I recall possibly reading it didn't use to allow at least one set of opposing lefts to go concurrently.
Illinois had a couple candidates for oldest:
* The former one on I-74 at 7th Avenue in Moline
* The stop sign controlled one on IL 137/Amstutz Expressway at Grand Avenue/Mathon Drive in Waukegan.
The SPUI on SR 201 at 3200 West (Exit 14) in Salt Lake City, Utah dates back to 1980:
https://www.google.com/maps/@40.7268644,-111.9681077,658m/data=!3m1!1e3
The SPUI here in Fairfax County at Gallows Road and Arlington Boulevard (US-50) was built in the early 1980s. I don't remember the exact year and a Google search didn't tell me, but it was after 1980. (I remember the construction itself, and I remember the crossroads that was there before the rebuild, but I just don't recall the exact years.)
https://goo.gl/maps/NoshrLgt6XJXfZ9K8
Quote from: Brian556 on May 19, 2020, 08:33:27 PM
There is a very old one in Ft Worth TX at SH 180 (Former US 80) (Lancaster Av) at Beach St
https://www.google.com/maps/@32.7438201,-97.2894799,362m/data=!3m1!1e3 (https://www.google.com/maps/@32.7438201,-97.2894799,362m/data=!3m1!1e3)
Yep, this is probably the answer.
https://www.aaroads.com/forum/index.php?topic=23144
The commonly cited first SPUI is US 19 and SR 60 in Clearwater, FL, which is newer.
Quote from: NE2 on May 20, 2020, 08:55:27 AM
Quote from: Brian556 on May 19, 2020, 08:33:27 PM
There is a very old one in Ft Worth TX at SH 180 (Former US 80) (Lancaster Av) at Beach St
https://www.google.com/maps/@32.7438201,-97.2894799,362m/data=!3m1!1e3 (https://www.google.com/maps/@32.7438201,-97.2894799,362m/data=!3m1!1e3)
Yep, this is probably the answer.
https://www.aaroads.com/forum/index.php?topic=23144
The commonly cited first SPUI is US 19 and SR 60 in Clearwater, FL, which is newer.
Are we including any of the old left-exit SPUIs in this, or just the modern-type SPUIs?
First SPUI in Kentucky was the intersection of US 60, US 421, and KY 676 in Frankfort. Built in the early 1980s.
Quote from: Revive 755 on May 19, 2020, 10:54:44 PM
I-170 at MO 180 is older than I-55 at US 50-61-67, though I recall possibly reading it didn't use to allow at least one set of opposing lefts to go concurrently.
Illinois had a couple candidates for oldest:
* The former one on I-74 at 7th Avenue in Moline
* The stop sign controlled one on IL 137/Amstutz Expressway at Grand Avenue/Mathon Drive in Waukegan.
Yeah, the 170 bridges do have that green-girder 90s look. And bc of the wide median the single point is between the NB and SB lanes, which is pretty unique and cool: https://www.google.pl/maps/@38.7048978,-90.3395114,3a,75y,288.49h,87.91t/data=!3m6!1e1!3m4!1sa4z8zcydnV-9IO8Njjqicg!2e0!7i16384!8i8192
Quote from: Brandon on May 20, 2020, 09:29:14 AM
Are we including any of the old left-exit SPUIs in this, or just the modern-type SPUIs?
I suppose if we were, an honourable mention might go to the terribly-signalized
290/Harlem Ave junction (https://goo.gl/maps/Dd462XpW78mrk8ks9) in Oak Park, IL, irrespective of its age.
But even then, not sure I would include these types of SPUIs since I don't most people think of them when they think of a traditional "SPUI" (even if Wiki says it's a legit variant called the "inverted SPUI").
Yeah, left exit SPUIs count.
Quote from: STLmapboy on May 20, 2020, 05:36:50 PM
Yeah, left exit SPUIs count.
How old is I-76 and South Street?
Has anyone here had the privilege of having to use one of those left entrance ramps?
Quote from: stridentweasel on May 20, 2020, 06:49:46 PM
Quote from: STLmapboy on May 20, 2020, 05:36:50 PM
Yeah, left exit SPUIs count.
How old is I-76 and South Street?
Has anyone here had the privilege of having to use one of those left entrance ramps?
I avoid those ramps...a left merge from a standstill with no merge lane...no thanks. The only saving grace is that normally traffic is backed up on I-76 enough that you can easily force your way in slow speed. Otherwise, it's either luck timing or quick acceleration.
In Reading PA, there is another example on US 422 and Bus US 222 which is pretty old.
I-110 at Hollywood Street, Baton Rouge. Half-SPUI constructed around 1969-70.
The I-73 SPUI at NC 42 in Asheboro NC was built about 1966
Quote from: Mapmikey on May 21, 2020, 08:49:11 PM
The I-73 SPUI at NC 42 in Asheboro NC was built about 1966
I know what the OP said, but I cannot see this as a SPUI. It just looks like a split diamond with left-side ramps:
(https://i.imgur.com/2OrIZbb.png)
Seems to me that the only SPUI-related things at these left-side examples is the turning movements (and even that's a stretch here given the straight-ahead movements). But that's going to be a given. The traditional SPUI with right-side ramps was infinitely more innovative on account of the simultaneous turns being able to occur despite their massive offset. Do these center-constructed interchanges have a "single point" for turns? Sure, but every intersection is a "single point", so I don't understand how these are even remotely related. Just having a single point for turns shouldn't automatically make an interchange a SPUI. Not to my eyes, at least. There are bigger things going on.
Quote from: Revive 755 on May 19, 2020, 10:54:44 PM
I-170 at MO 180 is older than I-55 at US 50-61-67, though I recall possibly reading it didn't use to allow at least one set of opposing lefts to go concurrently.
Illinois had a couple candidates for oldest:
* The former one on I-74 at 7th Avenue in Moline
* The stop sign controlled one on IL 137/Amstutz Expressway at Grand Avenue/Mathon Drive in Waukegan.
I used to hate having to use that exit. IIRC at some point the green light was really short.
Quote from: jemacedo9 on May 20, 2020, 08:18:00 PM
Quote from: stridentweasel on May 20, 2020, 06:49:46 PM
Quote from: STLmapboy on May 20, 2020, 05:36:50 PM
Yeah, left exit SPUIs count.
How old is I-76 and South Street?
Has anyone here had the privilege of having to use one of those left entrance ramps?
I avoid those ramps...a left merge from a standstill with no merge lane...no thanks. The only saving grace is that normally traffic is backed up on I-76 enough that you can easily force your way in slow speed. Otherwise, it's either luck timing or quick acceleration.
In Reading PA, there is another example on US 422 and Bus US 222 which is pretty old.
I've used both of these many times. They give you a bit of a challenge (especially 76) but not too bad.
Quote from: jakeroot on May 21, 2020, 08:57:40 PM
Quote from: Mapmikey on May 21, 2020, 08:49:11 PM
The I-73 SPUI at NC 42 in Asheboro NC was built about 1966
I know what the OP said, but I cannot see this as a SPUI. It just looks like a split diamond with left-side ramps:
Seems to me that the only SPUI-related things at these left-side examples is the turning movements (and even that's a stretch here given the straight-ahead movements). But that's going to be a given. The traditional SPUI with right-side ramps was infinitely more innovative on account of the simultaneous turns being able to occur despite their massive offset. Do these center-constructed interchanges have a "single point" for turns? Sure, but every intersection is a "single point", so I don't understand how these are even remotely related. Just having a single point for turns shouldn't automatically make an interchange a SPUI. Not to my eyes, at least. There are bigger things going on.
I agree. I thought SPUI's did not allow a "straight" movement to conflict with the left turns, while the left exits in the above example and the Reading example do. Also the intersections are tight and the right turning traffic would conflict with opposing left turn traffic, while SPUIs are channelized to minimize that conflict.
Quote from: Roadrunner75 on June 05, 2020, 07:48:39 PM
Quote from: jakeroot on May 21, 2020, 08:57:40 PM
Quote from: Mapmikey on May 21, 2020, 08:49:11 PM
The I-73 SPUI at NC 42 in Asheboro NC was built about 1966
I know what the OP said, but I cannot see this as a SPUI. It just looks like a split diamond with left-side ramps:
Seems to me that the only SPUI-related things at these left-side examples is the turning movements (and even that's a stretch here given the straight-ahead movements). But that's going to be a given. The traditional SPUI with right-side ramps was infinitely more innovative on account of the simultaneous turns being able to occur despite their massive offset. Do these center-constructed interchanges have a "single point" for turns? Sure, but every intersection is a "single point", so I don't understand how these are even remotely related. Just having a single point for turns shouldn't automatically make an interchange a SPUI. Not to my eyes, at least. There are bigger things going on.
I agree. I thought SPUI's did not allow a "straight" movement to conflict with the left turns, while the left exits in the above example and the Reading example do. Also the intersections are tight and the right turning traffic would conflict with opposing left turn traffic, while SPUIs are channelized to minimize that conflict.
To my knowledge, SPUIs do not have straight movements,
except those that do (https://goo.gl/maps/29HDjiFMsFsEdDx26). But I don't know if they're true* SPUIs anymore.
* "true" being the dilemma here; "true" to me is right-side ramps, no straight-ahead movement. It's as much a visual distinction as it is technical. But maybe others disagree.
I don't see how it matters what side of the highway traffic had exited from before reaching the intersection. Only the intersection itself should matter in defining a SPUI. As an analogue, I consider I-244 Exit #6A (https://goo.gl/maps/mwNMQ1X3JsAp44mU9) in Tulsa to be a split diamond interchange, even though one half of the diamond is between the I-244 roadways.
Quote from: jakeroot on June 06, 2020, 01:11:43 AM
To my knowledge, SPUIs do not have straight movements, except those that do (https://goo.gl/maps/29HDjiFMsFsEdDx26). But I don't know if they're true* SPUIs anymore.
* "true" being the dilemma here; "true" to me is right-side ramps, no straight-ahead movement. It's as much a visual distinction as it is technical. But maybe others disagree.
Here's a SPUI where one direction has a straight-through movement, but the other one doesn't: https://goo.gl/maps/xJvCCxN3mbg5fsvj6
I'm inclined to think it counts, since the main idea is to have a single intersection, but having straight-through movements does add to the signal phase count, so it's debatable.
On another note, here's a Super-2 with a SPUI: https://goo.gl/maps/kbqpNug2GUr3YY91A , and it also has straight-through movements. I wonder how many of those exist.
Edit: That Super-2 SPUI is also part of a split-diamond. For some reason, I was having trouble remembering the correct terminology when I mentioned that earlier.
Quote from: kphoger on June 09, 2020, 10:29:45 AM
I don't see how it matters what side of the highway traffic had exited from before reaching the intersection. Only the intersection itself should matter in defining a SPUI. As an analogue, I consider I-244 Exit #6A (https://goo.gl/maps/mwNMQ1X3JsAp44mU9) in Tulsa to be a split diamond interchange, even though one half of the diamond is between the I-244 roadways.
Do simultaneous left turns without a straight-on movement really need to be the only defining feature? Because, although that's the key with SPUI's, they're impressive because the ramps
usually start on the right and somehow don't overlap.
edit: horrible grammar.
A 1991 book about SPUIs can be downloaded here: http://ntrl.ntis.gov/NTRL/dashboard/searchResults/titleDetail/PB92167113.xhtml
It includes some with frontage roads (e.g. p. 7, p. 35) and talks about the one in Clearwater being first (p. 3), but the authors failed to find the earlier one in Fort Worth.
I think if I were road-geek-term-king...
SPUI: diamond form of interchange where neither the lefts on to or off of the freeway interlock and a 3-phase signal provides all movements.
Personally I consider an offset SPUI more of a SPUI than the ones with frontage road signal phases, because that 4th signal phase hurts efficiency. And I guess that goes out the window if the offset SPUI is a roundabout because now your lefts from the freeway hurt each other :banghead:
(https://encrypted-tbn0.gstatic.com/images?q=tbn%3AANd9GcRqNo88BcibZRTeqj-IsvKJDzjKbbrYVhk07_KjF1zYhsEcH4qO&usqp=CAU)
An interchange between US-13 (Military Hwy) and US-58 (Virginia Beach Blvd) (https://www.google.com/maps/@36.8556784,-76.2098645,224m/data=!3m1!1e3) in Norfolk, VA was constructed in the early 2000s to replace an older cloverleaf that was previously located there, and it's designed and striped like a SPUI (allowing both ramps to turn left at the same time), though also has straight through movements. From my experience driving through there, it seems to simply be timed to allow one off-ramp ramp at a time go both straight and left at once, instead of both left turning movements at the same time like a traditional SPUI.
Quote from: sprjus4 on June 17, 2020, 11:21:21 AM
An interchange between US-13 (Military Hwy) and US-58 (Virginia Beach Blvd) (https://www.google.com/maps/@36.8556784,-76.2098645,224m/data=!3m1!1e3) in Norfolk, VA was constructed in the early 2000s to replace an older cloverleaf that was previously located there, and it's designed and striped like a SPUI (allowing both ramps to turn left at the same time), though also has straight through movements. From my experience driving through there, it seems to simply be timed to allow one off-ramp ramp at a time go both straight and left at once, instead of both left turning movements at the same time like a traditional SPUI.
I find it interesting that, despite this phasing,
signs were installed (https://goo.gl/maps/452kixcxzRmjBA6S6) telling traffic how to perform the double left.
Quote from: sprjus4 on June 17, 2020, 11:21:21 AM
An interchange between US-13 (Military Hwy) and US-58 (Virginia Beach Blvd) (https://www.google.com/maps/@36.8556784,-76.2098645,224m/data=!3m1!1e3) in Norfolk, VA was constructed in the early 2000s to replace an older cloverleaf that was previously located there, and it's designed and striped like a SPUI (allowing both ramps to turn left at the same time), though also has straight through movements. From my experience driving through there, it seems to simply be timed to allow one off-ramp ramp at a time go both straight and left at once, instead of both left turning movements at the same time like a traditional SPUI.
ADOT in Arizona built dozens of these types of SPUIs in the Phoenix area with frontage roads in the late 1980s - early 2000s. Some of them are timed to allow both off ramps to turn left at the same time while others are timed to allow only one direction to go straight and left at the same time.
Greensboro NC has one that's been there probably as far back as when we first moved back to GSO. Wendover Ave at Holden Road would probably count as a SPUI since all off and on ramps converge on the same point. We moved to GSO in 1975.
I know the first SPUI in DuPage County was Butterfield Rd (Rt 56) at Highland Ave. I seem to recall that was done around 1988. The oldest on I-55 is the Pulaski Rd exit in Chicago. That one was done in 1997.
Memphis/Shelby County, TN is absolutely filled with SPUIs. I think they have the oldest one in TN at Walnut Grove Rd and Germantown Pkwy, which was built sometime in the 80's. Then a bunch of other ones were built along TN 385 Bill Morris Pkwy in the 90's and 00's. Eight SPUI exits in a row once past Hickory Hill Rd, then if you choose to take I-269 north (formerly TN 385), you hit one more.
Moline IL, 7th Ave under I-74
I-494 at 24th Ave in Bloomington, probably Mall of America related in the early 90s
I-35 at Lake Avenue in Duluth
Quote from: stridentweasel on June 09, 2020, 05:54:03 PM
Quote from: jakeroot on June 06, 2020, 01:11:43 AM
To my knowledge, SPUIs do not have straight movements, except those that do (https://goo.gl/maps/29HDjiFMsFsEdDx26). But I don't know if they're true* SPUIs anymore.
* "true" being the dilemma here; "true" to me is right-side ramps, no straight-ahead movement. It's as much a visual distinction as it is technical. But maybe others disagree.
Here's a SPUI where one direction has a straight-through movement, but the other one doesn't: https://goo.gl/maps/xJvCCxN3mbg5fsvj6
I'm inclined to think it counts, since the main idea is to have a single intersection, but having straight-through movements does add to the signal phase count, so it's debatable.
On another note, here's a Super-2 with a SPUI: https://goo.gl/maps/kbqpNug2GUr3YY91A , and it also has straight-through movements. I wonder how many of those exist.
Edit: That Super-2 SPUI is also part of a split-diamond. For some reason, I was having trouble remembering the correct terminology when I mentioned that earlier.
There is a SPUI in Castle Rock, CO that seems like it was built in preparation for the Super-2 it serves to be widened, but it is still a super-2!
In regards to SPUIs with straight movements, at Union and Austin Bluffs Pkwy in Co Spgs, there is a SPUI that has thru movements for busses only! Does that count?
Quote from: MCRoads on July 03, 2020, 12:04:21 PM
There is a SPUI in Castle Rock, CO that seems like it was built in preparation for the Super-2 it serves to be widened, but it is still a super-2!
That's actually one of my favorites, since the left turns have flashing yellow arrows. Permissive turns at SPUIs are pretty rare.
Google Maps link (https://goo.gl/maps/tJwLGoP7BmrWHoJ36)
milwaukee/dempster in niles il (kind of??) 1st Build in 1930's??
Quote from: jakeroot on July 04, 2020, 10:48:30 AM
Quote from: MCRoads on July 03, 2020, 12:04:21 PM
There is a SPUI in Castle Rock, CO that seems like it was built in preparation for the Super-2 it serves to be widened, but it is still a super-2!
That's actually one of my favorites, since the left turns have flashing yellow arrows. Permissive turns at SPUIs are pretty rare.
Google Maps link (https://goo.gl/maps/tJwLGoP7BmrWHoJ36)
Highway 2/Van Dorn Street at US 77 in Lincoln, NE also has a permissive lefts (https://goo.gl/maps/e66zojK2wq3Jgzzm6)
Quote from: Revive 755 on December 21, 2020, 10:27:40 PM
Quote from: jakeroot on July 04, 2020, 10:48:30 AM
Quote from: MCRoads on July 03, 2020, 12:04:21 PM
There is a SPUI in Castle Rock, CO that seems like it was built in preparation for the Super-2 it serves to be widened, but it is still a super-2!
That's actually one of my favorites, since the left turns have flashing yellow arrows. Permissive turns at SPUIs are pretty rare.
Google Maps link (https://goo.gl/maps/tJwLGoP7BmrWHoJ36)
Highway 2/Van Dorn Street at US 77 in Lincoln, NE also has a permissive lefts (https://goo.gl/maps/e66zojK2wq3Jgzzm6)
With excellent visibility, you have to wonder why this isn't more common. The length of a left turn, between the stop line and the clearance point, rarely seems to impact left turn signalization decisions at regular intersections...why at SPUIs? You could theoretically operate a SPUI without any protected left turns, and turn the whole interchange into a two-phase junction.
Quote from: Joe The Dragon on December 21, 2020, 09:34:15 PM
milwaukee/dempster in niles il (kind of??) 1st Build in 1930's??
Hmmm. SPUIs, as we know them today, typically allow for the off-ramps to proceed at the same time; this example only permits one off-ramp at a time. With that in mind, it seems more like a tight diamond.
From searching on google earth historical images for a bit:
I-270 and Sawmill was upgraded from a diamond to SPUI sometime between 1994 and 2002.
I-465 and Emerson was upgraded from a diamond to SPUI sometime between 1998 and 2003
Those 2 are far from the oldest in the country, but some of the ones older than I am.
Quote from: jakeroot on December 30, 2020, 04:21:05 AM
With excellent visibility, you have to wonder why this isn't more common. The length of a left turn, between the stop line and the clearance point, rarely seems to impact left turn signalization decisions at regular intersections.
I'm trying to remember the different guidelines for allowing permissive lefts (something to Google for fun later if you're bored!), but don't recall a factor for really large intersections. I know the intersection sight distance is based on opposing speed, which would be high in a SPUI. So my guesses why you don't see SPUI permisssive lefts often:
1. the conflict area is so large (due to the big radius and median width) and opposing speeds are so high that drivers won't generally be able to see far enough to judge that gap. For instance on the Nebraska example it looks like the conflict area is more than 100' from the stop line to beyond the opposing throughs. At most SPUI I don't think you'd really have any chance to pull into the intersection due to the large radius.
2. Many SPUI are on the crest of a vertical curve. Drivers trying to look for cars coming over a hill toward them on a tangent (fast) could lead to right angle crashes at relatively high speed - potentially serious crashes.
3. Many SPUI don't have "positive offset" (another fun Google topic!) for the opposing lefts. Basically someone trying to turn left the other direction will block your view of the throughs you need to yield to.
Quote from: SkyPesos on December 30, 2020, 03:25:03 PM
From searching on google earth historical images for a bit:
I-270 and Sawmill was upgraded from a diamond to SPUI sometime between 1994 and 2002.
I can tell you that the change from diamond to SPUI, for Sawmill @ I-270 occurred at the start of the 21st Century and was completed in 2002.
Quote from: johndoe on December 30, 2020, 10:57:23 PM
Quote from: jakeroot on December 30, 2020, 04:21:05 AM
With excellent visibility, you have to wonder why this isn't more common. The length of a left turn, between the stop line and the clearance point, rarely seems to impact left turn signalization decisions at regular intersections.
I'm trying to remember the different guidelines for allowing permissive lefts (something to Google for fun later if you're bored!), but don't recall a factor for really large intersections. I know the intersection sight distance is based on opposing speed, which would be high in a SPUI. So my guesses why you don't see SPUI permisssive lefts often:
1. the conflict area is so large (due to the big radius and median width) and opposing speeds are so high that drivers won't generally be able to see far enough to judge that gap. For instance on the Nebraska example it looks like the conflict area is more than 100' from the stop line to beyond the opposing throughs. At most SPUI I don't think you'd really have any chance to pull into the intersection due to the large radius.
2. Many SPUI are on the crest of a vertical curve. Drivers trying to look for cars coming over a hill toward them on a tangent (fast) could lead to right angle crashes at relatively high speed - potentially serious crashes.
3. Many SPUI don't have "positive offset" (another fun Google topic!) for the opposing lefts. Basically someone trying to turn left the other direction will block your view of the throughs you need to yield to.
I would say another big thing is that (4) so many SPUIs are double left turns, which are protected-only by rule in most areas.
If we could find a way to fully offset the left turns, to allow traffic to pull way into the intersection while waiting (ideally, where traffic would be waiting side-by-side to turn left), and then make the left turns sharper (pull forward, harder left), we could reduce the conflict area substantially. Making the left turns lagging would also be exceptionally important, unless we want an 8-second all red.
The problem with #3 would certainly persist no matter what, with only a reduced conflict area being able to actually help that (eliminating the problem entirely being quite difficult). But luckily, at least from my experience, most overpasses are relatively level. Plus, SPUIs that are at ground-level likely have more of a valley issue, which doesn't necessarily present issues with visibility.