2di's that are one lane in each direction thru a major interchange

[pumpkineater2]

 
One that comes to mind:
I-10 at the interchange with U.S. 90 and I-35 in San Antonio
Others?

[NE2]

Most routes that take ramps at an interchange.

[02 Park Ave]

The I-80 as it transistions from its concurrence with the Indiana East-West Toll Road to its concurrence with the I-94 in Northwest Indiana.

[briantroutman]

I-70 for a very short distance in Wheeling.

[US81]

Most routes that take ramps at an interchange.

Maybe it's a regional thing? It's not typical in Texas, though there are some, as mentioned above.

[Brandon]

The I-80 as it transistions from its concurrence with the Indiana East-West Toll Road to its concurrence with the I-94 in Northwest Indiana.

I-80 and I-74 through the Big X in the Quad Cities.

[NE2]

Most routes that take ramps at an interchange.

Maybe it's a regional thing? It's not typical in Texas, though there are some, as mentioned above.

Not too many Interstates in Texas take ramps. The only two obvious examples I can find are I-10 in San Antonio (twice, though one is more of an equal split) and I-410 in San Antonio (which definitely gets down to one lane at the north split, at least for now).

[pianocello]

The I-80 as it transistions from its concurrence with the Indiana East-West Toll Road to its concurrence with the I-94 in Northwest Indiana.

I-80 and I-74 through the Big X in the Quad Cities.

And I-74 just outside the Quad City Airport.

[briantroutman]

Most routes that take ramps at an interchange.

Maybe it's a regional thing? It's not typical in Texas, though there are some, as mentioned above.

Probably more common in the East due to a confluence of factors. Many eastern states were building substandard freeways prior to the 1956 Act, and in some cases, Interstate designations were strung along multiple existing roads. A prime example is I-83 in Harrisburg, which one-lane exits itself twice in a five-mile span as it snakes from the former US 111 expressway to the Harrisburg Expressway and finally to the prior Bypass 230 expressway. Coupled with the East's typically denser urban cores and higher land costs–and tapped out state highway departments that had shouldered a great deal of construction costs prior to the Interstate's 90% federal funding scheme–building proper thru movements was either not feasible or not a priority.

[hbelkins]

I-75 at I-640 and I-275 in Knoxville. I've seen traffic dog-knotted pretty badly southbound at the one-lane ramp that traffic has to use to stay on 75.

[SteveG1988]

I-55 and the Poplar st Bridge in St Louis.

[Brandon]

The I-80 as it transistions from its concurrence with the Indiana East-West Toll Road to its concurrence with the I-94 in Northwest Indiana.

I-80 and I-74 through the Big X in the Quad Cities.

And I-74 just outside the Quad City Airport.

And I-74 (again) at the northwest split between I-55 and I-74.

Then there's I-72 at I-55 (Clear Lake Ave) in Springfield.

And I-72 again near Hannibal at the split with I-172.

Need I mention I-39 at US-20 in Rockford?

[empirestate]

Most routes that take ramps at an interchange.

OK, so how about those that go to one lane, but don't appreciably change direction through the interchange? In other words, they form the through route both numerically and geometrically (meaning that the predominant flow of traffic takes a turn through the interchange, and changes numbers as it does so).

[hbelkins]

I'm old enough to remember when the southern split of I-75 and I-64 near Lexington was one lane in each direction. The traffic backups on the day before Thanksgiving and right before Christmas were legendary. They added a second lane around 1979-80 and a third lane at some later date.

[bzakharin]

I-76 Eastbound at exit 326 as it leaves the PA turnpike is briefly one lane before splitting into  2. I-76 Westbound is one lane for the entire loop as it enters the turnpike at the same location.

[US81]

 

Most routes that take ramps at an interchange.

Maybe it's a regional thing? It's not typical in Texas, though there are some, as mentioned above.

I'm going to apologize right now. Even with the OP example, an interchange I have driven through many times, I didn't stop to think. "Taking ramps" just didn't evoke "oh, like TOTSO" but it should have. I pictured the one lane going straight through the intersection with the other lane(s) exiting, say in a cloverleaf, and could think of a few historic examples but none extant. 

I am renewing my vow not to post when sleep-deprived.

...and now, returning to the scheduled thread already in progress....

[theline]

The I-80 as it transistions from its concurrence with the Indiana East-West Toll Road to its concurrence with the I-94 in Northwest Indiana.

For quite awhile I-80 has actually been zero lanes going westbound at that location, since the ramp was closed and then demolished. The detour goes down to one lane across multiple ramps from the ITR to I-65 south. They've promised to rebuild the WB ramp, though I'm sure it will remain one lane.

[Darkchylde]

I-70 at the northeast corner of the KC Downtown Loop. Eastbound, it keeps one lane, and though the way the interchange is built has it configured like an exit (one lane, right exit,) it is signed as the "through" movement. (No exit number - I-35 here is signed as the exit.) In the opposite direction, it has two lanes for a brief distance, but narrows to one before merging with I-35.

[lepidopteran]

I-75 at I-640 and I-275 in Knoxville. I've seen traffic dog-knotted pretty badly southbound at the one-lane ramp that traffic has to use to stay on 75.

Hey, before that bypass with the colorful overpasses was built (for the 1982 World's Fair?), I-75 NB traffic had to negotiate a tight cloverleaf ramp in the downtown area.  Probably easy-to-miss as well.

Also on I-75, at least one direction had only one through lane at the T-interchange with I-280 in Toledo.  Not sure when that was improved.

[vtk]

 I-70 westbound at I-71, east end of the overlap.  Of four lanes, the right two go to I-71 north, then the right lane of the two remaining is exit-only for the new downtown exit. I-70 westbound is then a single lane for about a half mile before I-71 southbound contributes a couple of lanes on the left.

[dfwmapper]

The furthest north portions of I-35W at the E/W split of I-35 in Denton, TX are one lane in each direction for a short distance. This may not last much longer because the interchange is being rebuilt.

I-35 at the I-40/I-235 interchange in downtown OKC uses a pair of one lane ramps.

I-49 follows a pair of one-lane ramps at each of its interchanges with I-44 near Joplin.

[Big John]

I-43 Hale interchange SW of Milwaukee: https://www.google.com/maps/@42.9612155,-88.0391969,3a,75y,40.88h,84.3t/data=!3m4!1e1!3m2!1sxQZdpiC77dRlo_2SU_TTJw!2e0

[sandwalk]

- Eastbound I-94 in Northbrook, Illinois just before where the road merges with US 41

- I-90 between where it branches off of the Ohio Turnpike (with I-80) and the Route 2 freeway in Elyria, Ohio

- Then there's the Ohio Turnpike I-76 and I-80 interchange where both interstates are reduced to one lane with numerous loop ramps and a toll booth near Youngstown

[rickmastfan67]

I-79 at both of it's interchanges with I-70 in Washington, PA (excludes NB at the Southern/Eastern interchange as that just recently got a new 2 lane mainline flyover).

[Strider]

I-73 at I-85/US 421/US 220 interchange south of Greensboro. Both I-73 North and South takes one lane ramps when they enter (I-73 North) or exit the Loop (I-73 South). I-73 and I-85 does not merge, but parallel each other at that location.