Steepness of grades on freeway-class roads

[cpzilliacus]

This past weekend, I drove I-64 in Virginia and West Virginia between I-81 in the east and Beckley for the first time ever, going to and coming from the New River Gorge Bridge Meet.

Driving east on I-64 from Beckley, I was impressed by the long and rather steep descent from CR 27 (Exit 133, Bragg) to the bridge over the New River, posted at 7%, about 6 miles from the top of the grade to WV-20 just past the  New River bridge.  In standard West Virginia fashion, there was a mandatory brake check stop for commercial vehicles prior to the start of the descent.

Not sure I have ever seen a 7% grade signed on a freeway in the U.S. before (I have driven some pretty steep Interstate system grades on  the Pennsylvania Turnpike; the Grapevine on I-5 in  California; I-80 westbound from Truckee, California to Sacramento; I-70 on both sides of the Eisenhower Tunnel in Colorado; and I-68 in Maryland and West Virginia and others).

Any other grades with a descent greater than 6% out there on freeways?

[formulanone]

I-10 near Kerrville, Texas has a 7% grade:



I thought I've heard that I-70 in Colorado has an even steeper grade?

[Max Rockatansky]

I would imagine that some of the non-Interstate freeways in California have sections above 6%.  58 west of Techapi feels like it has some 8-10% sections at times.  The problem is that Caltrans doesn't really post grades on signage aside from some big ones like CA 4/Ebbetts Pass or CA 108/Sonora Pass.  There isn't any resources really on road grades for state maintained highway that I've been able to find. 

[noelbotevera]

I think US 322 has a 7 or 8% grade on the freeway section "east" (really south) of Milroy. I know there's a sign, but I forgot where it is, and trying to pinpoint it on GSV came up fruitless.

[cl94]

NY generally doesn't sign percentages on freeways/parkways. That being said:

-I-84 has several steep grades across the state when crossing the Shawangunk Ridge and the Appalachians. I don't know the grades here, but these are probably the steepest Interstate grades in the state. The hill between the Taconic and NY 292 is roughly 550 feet of elevation gain. Delaware River to the Shawangunk high point is about 600 feet.
-I-87 has a couple nasty grades in the Adirondacks (most notably between Exits 30 31) and and on the western approach to Tappan Zee.
-I-88 has a couple just east of Binghamton
-NY 13's eastern approach to Ithaca is limited-access and quite steep. Probably steepest limited-access road in New York. 400' in about a mile.
-NY 17 has a few at/around the Shawangunks. If this ever becomes I-86, these will become the steepest Interstate grades.

Massachusetts has a nasty grade on the Mass Pike just west of Westfield. Probably the worst freeway grade in that state.

[RobbieL2415]

I-78 between Bethlehem and Easton, PA has a pretty steep grade.  I got stuck behind a parade of trucks there coming back from a funeral.

I-90 from the MA border to Worcester has some hilly sections, not really steep grades, but they wreck the flow of traffic during rush hour.

Other mentionable areas:

I-91 SB in Northampton, MA (Mount Thom)
I-84 east of Vernon, CT (mainly nuisance hills)
Taconic State Parkway north of I-84 (take your pick)
I-91 near Higby Mountain, Meriden, CT (if you frequent this part of the Interstate you know it as that one big hill before the interchange for the WC Parkway).

[OracleUsr]

I-68 going into Cumberland, MD, has a steep grade (not sure the %)
I-40 descending into Old Fort, NC, as well

[Brian556]

Ranger Hill on I-20 E of Abilene TX has a sub standardly steep grade. There's a whole nother thread bout that cuz they about to fix it.
https://www.aaroads.com/forum/index.php?topic=19656.0

I-24 @ Monteagle TN. There's also a thread about that one, but its pretty old now.
https://www.aaroads.com/forum/index.php?topic=3541.msg110203#msg110203

[sparker]

I-5 SB coming into Castaic and NB between Tejon and the valley touchdown at Grapevine don't have their gradient posted (as per Caltrans' usual practice), but the elevation change vis-a-vis mileage puts the NB grade at about 6.85% and the SB somewhere around 6.65% until the final segment (just before it crosses the NB lanes), where it increases to about 7.10% before leveling off.  Of course, both of these are downhill grades; Caltrans quite deliberately placed the uphill grades on the original expressway alignments, which usually "maxed out" just shy of 6%. 

[cpzilliacus]

There are certainly some grades I suspect are steeper than 6% on freeways (I-70 on either side of the Eisenhower Tunnel in Colordado are my top suspects, though IIRC, they are signed 6%), but the descent on I-64 was the first one I had ever seen where the state DOT expressly signed it as being steeper than 6%.

[mvak36]

The steepest one I drove through was on I-80 east of Laramie, WY. I can't remember how steep it was though.

[ColossalBlocks]

Interstate 55 has some pretty steep grades in the Southern half of Missouri, in between Sikeston and Scott City, Missouri to be specific. Gets down to what looks like 4% grade. And I-44 before you enter St Robers/Waynesville, Missouri has some steep grades, it also makes the linemen's jobs harder than needed because they have to come in with crane-mounted platforms to work on the wires.

[coldshoulder]

OH-711 in Youngstown, between Gypsy Lane and 422, has a 6% grade combined with a sharp curve that has made it a high-accident area, especially during icy/snowy conditions in the winter.  Southbound traffic (going downhill) is impacted the most. 

https://www.google.com/maps/@41.1268874,-80.6779878,2426m/data=!3m1!1e3

[cpzilliacus]

This page has an interesting discussion of some of the steeper descents on the highway network of the United States, including the Sandstone Mountain descent on I-64 in West Virginia.

[Buffaboy]

Well, I don't know the percentage so I won't speculate, but US-219 just south of North Boston, NY, has a pretty steep grade, most likely the steepest for a freeway in Western New York.

[akotchi]

I think US 322 has a 7 or 8% grade on the freeway section "east" (really south) of Milroy. I know there's a sign, but I forgot where it is, and trying to pinpoint it on GSV came up fruitless.

Seven Mountains Hill, which is actually west/north of Milroy on U.S. 322 has an 8% downgrade eastbound through the curvy 3-mile section.  I take that frequently on my trips to and from Penn State.

[DTComposer]

US-101 on the Conejo Grade between Thousand Oaks and Camarillo is 7%, according to the Wikipedia. Everything else about that section (shoulder/median width, etc.) seems to be Interstate standard (it's four lanes uphill, three lanes downhill).

The Cuesta Grade north of San Luis Obispo is 7% as well, but that's not Interstate standard (narrower shoulder/median, at least one at-grade crossing).

[thenetwork]

It's a 7% grade on at least one side of Vail Pass on I-70, and I believe the stretch of I-70 from Genesee to Golden Is also 7%

[jwolfer]

This is a surprising sign for Florida... I have to get a pic next time i am out that way. Coming into Callahan from the south on US301 there is a sign for a 5% grade on the descent from the railroad overpass

Its not a freeway but coming off a long stretch of 65 mph 4 lane divided rural highway

LGMS428

[Max Rockatansky]

This is a surprising sign for Florida... I have to get a pic next time i am out that way. Coming into Callahan from the south on US301 there is a sign for a 5% grade on the descent from the railroad overpass

Its not a freeway but coming off a long stretch of 65 mph 4 lane divided rural highway

LGMS428

I would assume FL 50 in Clermont is also 5% at least...again not a freeway but nothing you'd really expect in Florida.  There are some county routes out on the Brooksville Ridge that would definitely hit 8% like CR 41 in Pasco County.

[jwolfer]

This is a surprising sign for Florida... I have to get a pic next time i am out that way. Coming into Callahan from the south on US301 there is a sign for a 5% grade on the descent from the railroad overpass

Its not a freeway but coming off a long stretch of 65 mph 4 lane divided rural highway

LGMS428

I would assume FL 50 in Clermont is also 5% at least...again not a freeway but nothing you'd really expect in Florida.  There are some county routes out on the Brooksville Ridge that would definitely hit 8% like CR 41 in Pasco County.

Where i live in Florida Between Gainesville and Jacksonville is some of the higher ground in peninsular FL, near the Trail Ridge. There are places in neighborhood at around 100' ( i know nothing like mountains) some pretty cool ravines along Black Creek.

LGMS428

[hm insulators]

Southbound I-17 in Arizona has a long steep downgrade that traverses the Mogollon Rim just south of Flagstaff. Another downhill stretch of southbound 17 is just north of Black Canyon City.

In the Los Angeles area, the steepest grade I can think of is northbound I-405 coming down the Sepulveda Pass.

[noelbotevera]

As I came back from the NRG meet, I went through the grade the OP mentioned. I'm not sure how you can manage 70 MPH on a 7% grade without crashing.

Another one from West Virginia, though not a freeway: US 48. The highest grade it has is east of (I think) Buckhannon, at 8%.

[Bitmapped]

As I came back from the NRG meet, I went through the grade the OP mentioned. I'm not sure how you can manage 70 MPH on a 7% grade without crashing.

Easily. 10,000 cars do it every day on Sandstone Mountain.

Another one from West Virginia, though not a freeway: US 48. The highest grade it has is east of (I think) Buckhannon, at 8%.

The westbound descent to the Middle Fork River is a 7% grade.

[cpzilliacus]

In the Los Angeles area, the steepest grade I can think of is northbound I-405 coming down the Sepulveda Pass.

Is that steeper than the Grapevine (I-5) descent northbound in the southwest corner of Kern County?