Are there any interstates with one hilly lane and one flat lane?

[bugo]

There are plenty of what I call "Missouri Expressways," a 4 lane divided highway that was converted from a 2 lane.  The old lanes are often hilly while the new lanes are flat.  I've seen them on lots of expressways, but are there any actual freeways that are built like this?

[Alps]

The Pennsylvania Turnpike was briefly like this, where the new WB lanes twisted up a grade while the old EB lanes went through a tunnel on a different grade, but then the EB was built alongside the WB and the old lanes abandoned.

[J N Winkler]

There are, but the divergence in standard between the old and new lanes tends to be less pronounced because Interstate standards are strict.  Examples:  I-5 Grapevine (older lanes are steeper than newer lanes); I-24 Monteagle; and (I think) I-40 down old Fort Mountain.

[Takumi]

There's a brief section of I-95 in Stafford County, Virginia sort of like that. The southbound lanes are higher up than the northbound lanes.

[1995hoo]

Don't know about "flat versus hilly," but I can think of a couple of Interstates where one carriageway is located considerably higher up the side of a hill or mountain than the other side. The two that most readily come to mind are I-77 through the Fancy Gap area in Virginia and I-70 between the Mason-Dixon Line and Breezewood.

US-29 in Virginia has large portions that are not "freeway"-grade but are very good examples of a road that has frequent segments where one carriageway is flat and the other is hilly. The notorious speedtrap section just south of Madison is one such spot–the southbound lanes are a flat straightaway that encourages speeding, much to the delight of the local constabulary, while the northbound lanes are hilly.

[Compulov]

Don't know about "flat versus hilly," but I can think of a couple of Interstates where one carriageway is located considerably higher up the side of a hill or mountain than the other side. The two that most readily come to mind are I-77 through the Fancy Gap area in Virginia and I-70 between the Mason-Dixon Line and Breezewood.

I-8 though the western part of Imperial County follows two different paths through the mountains. I-17 through a few of the mountain ranges also rides two different elevations at a few points.
It's not an Interstate, but AZ-87 goes so far as to have one carriageway cross over the other and ride on right of the other for a bit. It's also a very fun drive for a four-lane divided highway.

[cpzilliacus]

US-29 in Virginia has large portions that are not "freeway"-grade but are very good examples of a road that has frequent segments where one carriageway is flat and the other is hilly. The notorious speedtrap section just south of Madison is one such spot–the southbound lanes are a flat straightaway that encourages speeding, much to the delight of the local constabulary, while the northbound lanes are hilly.

Sections of Md. 4 in Calvert County are like that. 

[Brian556]

I-24 at Monteagle was "fixed" in the 1980's.

[Bickendan]

I-84/US 30 climbing Emigrant Hill east of Pendleton is a great example.
The eastbound lanes run through a number of switchbacks as it climbs the hill and is at a lower grade than the westbound lanes which essentially plow straight down.

As a bonus, Old Emigrant Hill Rd is US 30's former routing.
http://goo.gl/maps/jbHiB

[Occidental Tourist]

I suppose that the I-5 north of Castaic would qualify.  The northbound lanes follow the path of the prior highway and wind around a bit.  I wouldn't really call it hilly though because the whole portion climbs a fairly steep a grade.  Some parts of the grade are steeper than others.

The southbound lanes have much fewer curves and are cut out of the foothills, with a consistent downgrade and no changes in grade.  This is the section that is known for the northbound lanes being on the west side of the southbound lanes.

[cwm1276]

Not a Interstate highway.  US 20 near Galena IL.  West bound has exit ramps on the new alignment while eastbound has an intersection eastbound.  Further west eastbound has more curves and hills than the new alignment.

https://maps.google.com/maps?q=galena+il&ll=42.461555,-90.514083&spn=0.018078,0.03931&oe=utf-8&client=firefox-a&hnear=Galena,+Jo+Daviess,+Illinois&gl=us&t=h&z=15

[hobsini2]

There are sections of I-39/90 and I-94 in Wisconsin that are significantly separated grades. I-39/90 southeast of Hwy N near Stoughton is one. There is also a crossroad north of Tomah on I-94 that the NWB lanes go over and the SEB lanes go under if I remember the setup correctly.

[mgk920]

There are sections of I-39/90 and I-94 in Wisconsin that are significantly separated grades. I-39/90 southeast of Hwy N near Stoughton is one. There is also a crossroad north of Tomah on I-94 that the NWB lanes go over and the SEB lanes go under if I remember the setup correctly.

That was just the two sides being engineered on separate routings, but as 'new' roadways that were both built at the same time.  OTOH, A true I-route in Wisconsin like that is I-39 running northwards from Westfield.  SB is the original mid-1960s US 51, highly engineered and very straight and level, while the NB side was built in the 1980s on a much hillier and curvier routing that much more closely follows the contours of the hills that it passes through.

Mike

[on_wisconsin]

There is also an 'over-under' pass on the Interstate triplex just east of the Wisconsin River. http://binged.it/PUDaRR

[Revive 755]

There's a section of I-44 in Missouri that kind of comes close, but both sides have a hill.  EB (downhill) seems to be a bit more planned/straighter compared to the westbound (uphill) lanes:

http://maps.google.com/maps?hl=en&ll=37.901475,-92.005134&spn=0.02875,0.066047&t=p&z=15

I recall a section of I-44 between MO 141 and MO 109 that used to meet the criteria, with the EB lanes staying flat while the WB lanes went up a hill, but the grade difference was removed back when that section was widened to six lanes.  I haven't had luck determining where exactly it was on either Google Earth or historic aerials.

[hbelkins]

There's a section of I-65 north of Nashville that has the two carriageways on separate alignments, to the point where one interchange has the interstate going over the intersecting route on one side, and the intersecting route crossing over the interstate on the other side.

[JREwing78]

I-94 east of Jackson near Grass Lake has this feature; the WBD lanes are the improved, relocated 2-lane US-12 that bypassed Grass Lake, later 4-laned and converted to Interstate. This stretch goes up and down a lot of smaller hills. EBD was added later, and is on a more constant grade.

You'll note east of Jackson, the original US-12 (Michigan Ave) remains, as well as the upgraded version (Ann Arbor Rd). The original Michigan Ave was narrower and had a narrow, short underpass of the railroad west of Grass Lake (http://goo.gl/maps/piZDD).

You'll also see it farther east on I-94 just west of Chelsea, where it crosses the railroad. The original section (now WBD) has an underpass with a rather steep climb headed west. EBD has a couple sharp curves and an overpass of the railroad about 800 feet SW of the underpass.

[Brandon]

Not an interstate in Illinois, but IL-53 is like that from Wilmington to Elwood.  One side even has all the older bridges intact.

[triplemultiplex]

That was just the two sides being engineered on separate routings, but as 'new' roadways that were both built at the same time.  OTOH, A true I-route in Wisconsin like that is I-39 running northwards from Westfield.  SB is the original mid-1960s US 51, highly engineered and very straight and level, while the NB side was built in the 1980s on a much hillier and curvier routing that much more closely follows the contours of the hills that it passes through.

Huh, I always assumed the flatter SB lanes were the newer ones.  That's interesting.  But I guess that makes sense now because there's a few spots on US 53 between Spooner and Solon Springs where the 'new' side is more hilly than the original.  And it would be cheaper to build without flattening as many hills.

[national highway 1]

I-8 in Imperial County has a 1.5mi (2.4km) wide median at the In-Ko-Pah/Mountain Springs grade where it descends 4000ft (1200m) in 11 miles. There is also a brief section east of Yuma where the carriageway switches over.
Also here is a section of the Federal Hwy (NH23) between Goulburn and Canberra, the southbound carriageway is the original undulating highway. The northbound carriageway was constructed in the 1970s.
http://goo.gl/maps/fKLk5

[JustDrive]

I-5 north of Shasta Lake and I-580 at Altamont Pass also qualify.

[tdindy88]

SR 37 in northern Monroe County in Indiana is like this with the northbound lanes following the original (but not the first) routing of SR 37 through generally wooded terrain and on relatively flat ground, while the southbound lanes (which were added when the highway was twinned) go up an incline and then back down to meet the northbound lanes, splitting the carriageways for about a mile. The southbound lanes also have more open space off the roads, indicating that these are the newer lanes. While this isn't an interstate, it may be part of one in the future as Interstate 69 will be routed up this way. Exactly how the highway will be configured through this area is still up for discussion however.

[cpzilliacus]

There are plenty of what I call "Missouri Expressways," a 4 lane divided highway that was converted from a 2 lane.  The old lanes are often hilly while the new lanes are flat.  I've seen them on lots of expressways, but are there any actual freeways that are built like this?

In a variation on that theme, I-95 between Petersburg, Va. and Emporia, Va. was built next to U.S. 301, which was a four-land divided arterial.  The southbound lanes of I-95 were once the northbound lanes of 301 (which is now a two-lane undivided highway running parallel to I-95 on its west side).  Because this part of Virginia is pretty flat, I don't know how much reconstruction of former U.S. 301 was needed to convert it to the southbound lanes of I-95. I think this might have been the last segment of I-95 in Virginia to be completed. 

[Takumi]

^ It was, in the early 1980s. There are a few rolling hills along that section of US 301, but the main elevation changes are to accommodate for side roads that now have to go over I-95 to meet 301.

There are still a handful of state-name I-95 shields in this area as well. There were more until last year.

[Sykotyk]

US422 between Warren and Parkman have stretches of this. WB is flat while EB is like a roller coaster.