Unique projects needed to upgrade to freeway/expressway standards?

[RM42]

I was reading about I-90 today and discovered the story of Wallace, ID. Wallace was right on the path of former US 10 and in the 70s that portion was designated I-90. All through traffic had to go through the town center in a couplet. Original freeway plans called for demolishing much of the town center, so residents got it placed it on the NRHP. Eventually the freeway was built, but as an elevated segment built into the hillside to the north of town. The former WB part of the couplet is now designated I-90 BUS.

http://www.gribblenation.org/2022/02/former-us-route-10-in-wallace-idaho.html

https://goo.gl/maps/3e1wUjaBpjN4Zjh97

https://goo.gl/maps/Qd3DgC6yCMSYrwuA9

What are some similarly unique scenarios (ie more than an engineering/permitting/financial issue) faced in upgrading to freeways/expressways? Interstates or non-Interstates welcome.

[froggie]

Two of the more famous (or infamous, if you prefer) examples would be the Glenwood Canyon section of I-70 in Colorado, and I-93 through Franconia Notch in New Hampshire.

[J N Winkler]

Another is I-10 through downtown Phoenix--I believe this was the last segment needed to finish the entire transcontinental route, and it entailed building the Deck Park Tunnel as well as the I-10/I-17 Maltese cross stack (first of the present five in Arizona).

[Bruce]

The Seattle-Bellevue section of I-90 has a bunch of engineering feats, including several accomplished during the 1980s to bring it up to Interstate standards:

- A brand new floating bridge with 7 lanes of traffic and a bike path
- An extension of an existing tunnel to fit a park lid
- A new tunnel with separate bores for bikes/pedestrians and a new carriageway
- Current conversion of said new carriageway into light rail, which will be the first permanent railway on a floating bridge in the world
- Several new park lids on Mercer Island to cover up deep excavations

[Henry]

If you drive on I-95 between Washington and New York, you'll get at least five engineering marvels along the way. These include the following:

• Rebuilt Springfield Interchange
• New Woodrow Wilson Bridge
• Ft. McHenry Tunnel
• PA Turnpike Interchange
• NJ Turnpike Local-Express Setup

[kphoger]

If you drive on I-95 between Washington and New York, you'll get at least five engineering marvels along the way. These include the following:

• Rebuilt Springfield Interchange
• New Woodrow Wilson Bridge
• Ft. McHenry Tunnel
• PA Turnpike Interchange
• NJ Turnpike Local-Express Setup

What about each of those projects is unique?

Was the highway not up to freeway/expressway standards before that?

[Ted$8roadFan]

Not sure if Boston's Big Dig counts.

[Rothman]

Not sure that much counts given the "engineering/permitting/financing" exemptions in the OP.

[RM42]

Not sure that much counts given the "engineering/permitting/financing" exemptions in the OP.

I mean I don't want this to turn into a list of different types of bridges. The case of Wallace is clearly more than just designing a bridge to put across a river.

[Occidental Tourist]

Interstate 5 between Castaic, CA and Pyramid Lake.  The old four-lane highway (US 99) ascending the Castaic Grade was paved into the n/b lanes of I-5, and a new s/b carriageway was built approx. 1/4 mile east of the existing highway.  For 4 1/2 miles, the highway is essentially like a British motorway, with opposing traffic to your right instead of left.

It required two bridges to be built at each end of the grade to switch each direction of travel back up to the correct sides of the roadway at either end.  There's even a paintball park in between the reverse carraigeways.

[thspfc]

I was reading about I-90 today and discovered the story of Wallace, ID. Wallace was right on the path of former US 10 and in the 70s that portion was designated I-90. All through traffic had to go through the town center in a couplet. Original freeway plans called for demolishing much of the town center, so residents got it placed it on the NRHP. Eventually the freeway was built, but as an elevated segment built into the hillside to the north of town. The former WB part of the couplet is now designated I-90 BUS.

http://www.gribblenation.org/2022/02/former-us-route-10-in-wallace-idaho.html

https://goo.gl/maps/3e1wUjaBpjN4Zjh97

https://goo.gl/maps/Qd3DgC6yCMSYrwuA9

What are some similarly unique scenarios (ie more than an engineering/permitting/financial issue) faced in upgrading to freeways/expressways? Interstates or non-Interstates welcome.

This reminds me of I-70 through Idaho Springs, CO.

[Sykotyk]

I'd say I-8 in *Arizona* having to go contraflow for a while due to twinning the original route through the mountains.

https://www.google.com/maps/@32.6670008,-114.3167719,14.25z?entry=ttu

[kphoger]

Interstate 5 between Castaic, CA and Pyramid Lake ... with opposing traffic to your right instead of left.

I'd say I-8 in *Arizona* having to go contraflow for a while ...

OK, you two can decide between yourselves which one is the unique one.