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

[vtk]

I-74 west bound at I-275 reduces to one lane. It looks like this wasn't always the case.

[jakeroot]

I swear to Christ somewhere in LA, I-5 South drops to one lane but I cannot figure out where. Perhaps I'm delusional.

[US81]

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.

I-35W (southbound) at the Hillsboro split, although that is being reconstructed, too.

[SSOWorld]

I swear to Christ somewhere in LA, I-5 South drops to one lane but I cannot figure out where. Perhaps I'm delusional.

East LA Interchange downtown (with I-10, US-101 and SR-60.)

[kendancy66]

I am fairly certain that I-5 South never narrows down to less than 2 lanes.  I closest instance I can think of is where I-5 South and CA-60 East branches off to the left from I-10 west.  What they did there was add a second exit lane over a previous gore area, that I never use because it is way too rough.

[dfwmapper]

I-35W (southbound) at the Hillsboro split, although that is being reconstructed, too.

The rebuild of the Hillsboro split was finished in 2009.

[US81]

I-35W (southbound) at the Hillsboro split, although that is being reconstructed, too.

The rebuild of the Hillsboro split was finished in 2009.

It's hard to notice that a particular segment is done with all the ongoing construction on I-35, but I stand corrected.   

(Wow, was it really that long ago? I know I've been thru there since then several times. Senility, I guess)

[NE2]

Also I-35W ends there, so it doesn't count.

[pianocello]

Both Mixmasters in Des Moines (the I-35/80/235 junctions) feature these: I-35 on the east end, and I-80 on the west. The east mixer is interesting southbound because the obvious thru movement (I-35 SB -> I-235 WB) is signed as a Left exit. (Street View)

[NE2]

The east mixer is interesting southbound because the obvious thru movement (I-35 SB -> I-235 WB) is signed as a Left exit. (Street View)

Blame the MUTCD.

[dfwmapper]

I-74 where it splits off from I-465 on the east side of Indianapolis. Used to be the same on the west side until the interchange was rebuilt a couple years ago. I-74 shows up a lot on this list.

[NE2]

Are there any cases where it clearly doesn't take a ramp or merges equally with another route (such as I-74 west at I-275), but takes the obvious straight movement yet still goes down to one lane? For example, SR 125 south at I-8 in San Diego would count if the former were an Interstate.

[jakeroot]

I-705 in Tacoma is one lane for about 500 yards (gore to gore) as exit and entrance ramps split and join respectively ... the thru lane is on the right:



Image from Interstate-Guide.com

Fucking hell nevermind, it's a 3di.

[Ned Weasel]

Are there any cases where it clearly doesn't take a ramp or merges equally with another route (such as I-74 west at I-275), but takes the obvious straight movement yet still goes down to one lane? For example, SR 125 south at I-8 in San Diego would count if the former were an Interstate.

It was already mentioned in this thread, and I'm not sure whether it meets the OP's definition of "major interchange," but I-70 and NB WV 2 (Wheeling) is the only one that comes to mind.  I'm pretty sure the lane reduction was made for the sake of avoiding sudden merges at the bridge and tunnel approaches, given the short distance (but that's probably old news to everyone here).

[NE2]

Damn, forgot about I-70 Wheeling.

[dfwmapper]

I-8 eastbound drops to a single lane just before it merges with the ramp from I-5 southbound in San Diego.