Why was I-70 four-laned through the San Raphel Swell

[Avalanchez71]

The two lane segment was more than sufficient to handle the flow of traffic.  Why did Utah spend the money there to upgrade to four-lane standards?  Was funding held up due to insufficiency?

[froggie]

Because Congress, in the late 1960s, mandated that the entire Interstate system be at least 4 lanes.

[skluth]

Because Congress, in the late 1960s, mandated that the entire Interstate system be at least 4 lanes.

I'm guessing an exception was made for Franconia Notch. Are there any other places with two lane interstates?

[Scott5114]

The point of the interstate system was never to be "sufficient". It was to meet the transportation needs of the United States in 1972. Given that they were planning it in 1956...

[US 89]

Because Congress, in the late 1960s, mandated that the entire Interstate system be at least 4 lanes.

I'm guessing an exception was made for Franconia Notch. Are there any other places with two lane interstates?

Alaska

[froggie]

Because Congress, in the late 1960s, mandated that the entire Interstate system be at least 4 lanes.

I'm guessing an exception was made for Franconia Notch. Are there any other places with two lane interstates?

Correct, an exception was made there.  Only other places I can think of offhand are the Sault Ste Marie Bridge on I-75 and the Thousand Islands Bridge on I-81.  Both go to the Canadian Border and both are toll bridges, so those are key factors.

I'm not counting Alaska because, while Interstates technically exist there, they exist mainly as a funding category and the Alaskan ones are not required to meet Interstate standards, nor are they considered full Interstates.

[oscar]

I'm not counting Alaska because, while Interstates technically exist there, they exist mainly as a funding category and the Alaskan ones are not required to meet Interstate standards, nor are they considered full Interstates.

Ditto Puerto Rico, included in the same law, as an act of noblesse oblige by the porkmeister behind the Alaska Interstates. The Puerto Rico Interstates include some non-freeway segments, but they might be at least four-lane divided.

[silverback1065]

Alaska and Puerto Rico don't have real interstates. they aren't even signed as interstates.

[zzcarp]

It's a pretty short stretch, and I-70 in Wheeling, WV has a short section of 1 lane in each direction at the west portal of the Wheeling Tunnel.

[oscar]

Alaska and Puerto Rico don't have real interstates. they aren't even signed as interstates.

The extra Interstate money those highways got, especially under the old funding formulas, certainly was real. But yeah, the Alaska Interstates are hardly noticed by the people up there.

[cpzilliacus]

As I have mentioned on this site before, I-95 in Maine north of Bangor was a Super-2 (widening out to 4 lanes divided at the interchanges) all the way to Houlton.

If the decision was to be made just on traffic volumes, it could still be a Super-2.  But federal policy, combined with many head-on crashes by drivers forgetting that they were on a 2-lane undivided highway (there were many signs reminding drivers of this), led to all of it getting a new roadway added, so it is now 4 lanes divided.

[Avalanchez71]

When I-70 was two lanes I can't recall but were there any exits in the area?

[Bitmapped]

It's a pretty short stretch, and I-70 in Wheeling, WV has a short section of 1 lane in each direction at the west portal of the Wheeling Tunnel.

The one lane part is going through an interchange, and wasactually built 2 lanes wide. WVDOH decided it was better to make this a drop/add situation with ramp traffic rather than providing no deceleration and acceleration lanes. 1-lane ramps through interchanges aren't all that unusual.

[WillWeaverRVA]

Alaska and Puerto Rico don't have real interstates. they aren't even signed as interstates.

The Puerto Rico ones are at least freeways (specifically, toll roads) for their entire length.

[oscar]

Alaska and Puerto Rico don't have real interstates. they aren't even signed as interstates.

The Puerto Rico ones are at least freeways (specifically, toll roads) for their entire length.

Not all of them. I-PR2 through Mayaguez, for example, has significant at-grade intersections with stoplights. Ditto I-PR3 east of San Juan, even the parts without a parallel toll freeway (onto which the paper Interstate hasn't been rerouted, AFAIK).

[Mapmikey]

When I-70 was two lanes I can't recall but were there any exits in the area?

Yes.  1968 Historic Aerial shows exit at UT 24 and 1983 topos further west (no aerial shots in the right timeframe) show exits, too.