Oldest SPUIs?

[STLmapboy]

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?

[Brian556]

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

[Roadgeekteen]

NE2 might be one of the oldest, don't know when he was born.

[TheHighwayMan3561]

NE2 might be one of the oldest, don't know when he was born.

Nope. According to his profile he's only 12.

[STLmapboy]

NE2 might be one of the oldest, don't know when he was born.

Nope. According to his profile he's only 12.

Most political and profane 12yo I've ever met then.

[Elm]

In Denver, Colorado, the SPUI at Santa Fe Dr (US 85) and Evans Ave (map) seems to have been put in sometime between 1983 and 1986, going by this report 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).

In Colorado Springs, the SPUI at I-25 and Garden of the Gods Rd was built in 1988 (map; ROW plans); 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); the bridges are from 1989, and I want to say the interchange has only ever been a SPUI.

[Revive 755]

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.

[US 89]

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

[1995hoo]

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

[NE2]

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

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.

[Brandon]

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

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?

[hbelkins]

First SPUI in Kentucky was the intersection of US 60, US 421, and KY 676 in Frankfort. Built in the early 1980s.

[STLmapboy]

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

[jakeroot]

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 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").

[STLmapboy]

Yeah, left exit SPUIs count.

[Ned Weasel]

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?

[jemacedo9]

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.

[Urban Prairie Schooner]

I-110 at Hollywood Street, Baton Rouge. Half-SPUI constructed around 1969-70.

[Mapmikey]

The I-73 SPUI at NC 42 in Asheboro NC was built about 1966

[jakeroot]

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.

[CapeCodder]

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.

[Roadrunner75]

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.

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.

[jakeroot]

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. 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.

[kphoger]

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 in Tulsa to be a split diamond interchange, even though one half of the diamond is between the I-244 roadways.

[Ned Weasel]

To my knowledge, SPUIs do not have straight movements, except those that do. 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.