What's the biggest interchange in your state? Is it the best designed?

[nwi_navigator_1181]

With all respect to Indianapolis, I gotta go with the I-65/80/94 interchange, which covers a wide swath.

The interchange includes the "Northwest Connector,"  carrying the largest volume of traffic and separate from the rest of the interchange because of a nearby railroad (for those unfamiliar, this connector carries traffic from I-65 north to I-80/94 west, and I-80/94 east to I-65 south).

Also of note are the recent integrations of Ridge Road, Central Avenue, and (to a lesser extent, with auxiliary lanes) Broadway, with the use of collector-distributor ramps. What was once a triangle of separate, rapid-fire interchanges is now a large area of continuously flowing movements. Through traffic on either freeway will have traversed nearly three miles from end to end when all is said and done.

The nearby Toll Road/15th Avenue/I-65/US 12/20 ramp system is up there too, even more so after the 2003 enhancements.

[kurumi]

In Connecticut, I-84/384/291 with US 6/44 and Buckland Street (late 1980s) is the largest interchange complex. The design has held up well IMO; good capacity with minimal weaving. It does take up a lot of land, and some movements to and from US 6/44 are missing.

As for single interchanges, what's the biggest? I compared the likely candidates at the same scale and the winner appears to be I-91 and CT 9 in Cromwell.



Is it best designed? No; it was built in two stages, 20 years apart, and the later design was a more modern take on the original.

The original design was a (spiderweb? cat's cradle?) 4-way directional, with 4 left exits, two long and two short. It would have been symmetrical. Half of that was built in 1969 for Route 9 south (to the southeast). Twenty years later, for Route 9 north (to the west), engineers were like "yeah, no" to the other 2 left exits, and replaced them with a semidirectional flyover and loop.

[achilles765]

Well I live in Texas which is apparently the stack interchange capital of America. The biggest is probably the high five in Dallas. US 75 and IH 635—there are 43 bridges, and some ranks are as high as a 12 story building. Look at a video online of someone driving through it. It's a serious wow factor especially now that those express lanes have been built along 635 (watch a clip of eBay that's like to drive through.)
But there's also usually a four or five level stack at almost all major freeway-freeway junctions.
The biggest here in Houston, depending on how one defines big is probably the newly redesigned IH69/US59 at IH 610 interchange in southwest Houston. Though interstate 10 at IH 610 just a few miles north of it is impressive too. As is the exit on the east side where IH 10, IH 610 and US 90 meet.
Most of the others all kind of look the same.
And generally these are all well designed I would say. Unless it's rush hour or there's a wreck, flood, or construction.

[achilles765]

Oh and apparently El Paso is about to have a really neat one on US 54 from the airport all the way to the already impressive exit with IH10.
Come to think of it IH 35/US 87/IH 10/US 90 in San Antonio is really cool, with the ramps and then the two interstates running concurrently double decked for a couple of miles.

[Bruce]

I-5 at I-90 in Seattle has all the requisite ramps, but is poorly suited to modern needs. The turns for some ramps are too tight, the I-5 SB to I-90 EB connection dumps into the wrong side (forcing a very short three-lane merge to reach Rainier Ave), and the lanes need to be rebalanced. At least the views are nice.

[CtrlAltDel]

I-5 at I-90 in Seattle has all the requisite ramps, but is poorly suited to modern needs. The turns for some ramps are too tight, the I-5 SB to I-90 WB connection dumps into the wrong side (forcing a very short three-lane merge to reach Rainier Ave), and the lanes need to be rebalanced. At least the views are nice.

Did you mean: the I-5 SB to I-90 EB connection?

[Bruce]

I-5 at I-90 in Seattle has all the requisite ramps, but is poorly suited to modern needs. The turns for some ramps are too tight, the I-5 SB to I-90 WB connection dumps into the wrong side (forcing a very short three-lane merge to reach Rainier Ave), and the lanes need to be rebalanced. At least the views are nice.

Did you mean: the I-5 SB to I-90 EB connection?

Whoops. Fixed in my post, but the WB connection is also a bit lacking in terms of signage.

[Ryctor2018]

This insanity: https://imgur.com/a/26ZiU6W. Though you can say it is several interchanges intersecting 4 highways in close proximity instead of directly. I'm told the Hillside strangler used to be worse; I've only lived in Chicagoland for a dozen years.

[andrepoiy]

In the Toronto area, there's 3 large ones by land area, I think they're similar in size. These images were are not to the same scale.

1) Hwy 401/427/27 Interchange in Etobicoke, Ontario. This massive interchange was supposed to also connect to the un-built Richview Expressway, which was supposed to be where Eglinton Avenue is right now on the east side.




2) Highway 401/403/410 Interchange in Mississauga, Ontario. This massive interchange was actually an incomplete interchange until 2018, when they added a ramp for Eastbound 401 -> 403 and a ramp for 403 -> Westbound 401.



3) Highway 407 ETR/Highway 400 Interchange in Vaughan, Ontario. It is the only proper 4-level stack interchange in the whole country. Due to the 407 ETR being a privately-owned toll freeway, traffic numbers are relatively lower than non-tolled freeways, so this interchange is never at full capacity.