One Ramp Interchanges

[roadman65]

Do not want slip ramps from freeway to service/ frontage roads, but one like NJ 21 & NJ 7 in Belleville, NJ.

The aforementioned one above is an interchange that has one NB ramp from Route 21 to NJ Route 7.  NJ 7 has no ramps onto the NJ 21 freeway in either direction as well as SB NJ 21 having no ramp to NJ 7.

Also I-280 in Newark, now has one ramp EB to MLK Jr. Blvd after the NJ 21 interchange got reconfigured a few years ago.  Originally that one had three ramps lacking a WB entrance only.  Now the WB ramp for both Broad Street and MLK Blvd via State Street is gone and the EB entrance from MLK Jr. is since been removed.

Any others like these two in NJ?

[JoePCool14]

The only one I can think about is at I-94 eastbound to IL-50 Cicero Ave southbound. That's the only ramp there, though the other movements are covered by nearby Foster Ave and Peterson Ave/Caldwell Ave exits.
https://www.google.com/maps/@41.9823123,-87.7516024,16.25z

[Hot Rod Hootenanny]

I-90 EB to Carnegie Ave in Cleveland.

[SkyPesos]

I-64 WB exit 28B to Clayton Rd in St Louis

[froggie]

I-94 Exit 239A in St. Paul, MN, a single westbound off-ramp to Hamline Ave.

Due to ramp closures related to the I-40 Desoto Bridge closure in Memphis, I-55/Metal Museum Dr (Exit 12C) is effectively a "one-ramp interchange", with only the southbound exit ramp remaining open.

I-95 Exit 12 near Emporia, VA is a single northbound exit ramp to northbound US 301.

[Crown Victoria]

I-78 Exit 58 in Allentown, PA consists of one ramp from westbound I-78 to southbound Emaus Avenue.

https://www.google.com/maps/@40.5637555,-75.4763996,17.25z?hl=en

[jp the roadgeek]

The on-ramp from US 5 (Main St) to I-84 West in East Hartford, CT.  Also used to be a single entrance ramp to I-91 North in Windsor from Bina Ave before I-291 was constructed

[tolbs17]

US-64 in Creswell, NC

[Great Lakes Roads]

Former example: NB Keystone at 146th Street. SB onramp added in 2019.

[amroad17]

I-481 Exit 11 Caughdenoy Rd., Maple Rd. in North Syracuse, NY
https://goo.gl/maps/2ixJm7PSiXBkr4Zn8

[Roadgeekteen]

I-95/Dedham Street, exit has been around for a while, more ramps under construction

https://www.google.com/maps/@42.1926242,-71.1522875,17z

[GenExpwy]

I-390 southbound Exit 15B, Brighton—Henrietta Town Line Road, Rochester suburbs
https://www.google.com/maps/@43.0965261,-77.6023857,769m/data=!3m1!1e3

US 15 [Future I-99] southbound Exit 143, PA 973, north of Williamsport
https://www.google.com/maps/@41.3207001,-77.0946958,559m/data=!3m1!1e3

Long-ago example: NY 17, prior to construction of the Corning bypass, had an un-numbered [could have been 45, but wasn't] westbound exit to the village of Riverside

[Terry Shea]

Here's a really stupid one!  Business Spur I-196.  You can only exit onto it going EB on I-196.  There is no entrance ramp returning to EB I-196 and since it's a spur, the route doesn't complete a loop.  There is a ramp back to WB I-196, but there is no exit from WB I-196 to Business Spur I-196.  Apparently they designed it this way because for whatever reason they didn't want anyone continuing in the same direction after exiting.  I would also question why they built such long ramps to a parallel roadway in the first place, especially since the same road has a full interchange with I-196 a few miles back.  And then there is the question of whether this actually serves as a practical business route.
https://www.google.com/maps/place/I-196,+Grandville,+MI/@42.9316076,-85.7502946,14z/data=!4m5!3m4!1s0x8810ab49a162566f:0xedfb017b6f9408cd!8m2!3d42.9251398!4d-85.7496504

[DandyDan]

Omaha has the WB I-80 exit ramp to Q Street. There's also the SB US 75 to EB I-480 exit ramp to 24th Street by the Creighton campus.

[TheGrassGuy]

The Freehold Bypass (NJ-33) has an interchange with Howell Rd consisting of a sole SB-WB onramp.

Exit 41 of I-68 is a single WB offramp.

[Ned Weasel]

Southbound I-35 to 37th Avenue in Kansas City, Kansas sort of counts, and it used to count more, because the off-ramp used to be separate from the ramp to Southwest Boulevard and Mission Road.  https://goo.gl/maps/W7kiyAFwoXzJiCjK7

[1995hoo]

A prior thread about this topic can be found at the following:

https://www.aaroads.com/forum/index.php?topic=8980.msg208892#msg208892

[GaryV]

There are a lot of partial intersections on I-94 on the west side of Detroit near US-12.  A couple of them are single-ramp.
https://www.google.com/maps/@42.3309629,-83.1439762,16z?hl=en

[JayhawkCO]

A bunch of these in Seattle.

I-5 Northbound to Madison Street

I-5 Southbound to Airport Way

I-5 Southbound to 6th Avenue South/Forest Street

Chris

[jmacswimmer]

Old MA 15 onramp to I-84 WB just north of the CT/MA border.

Mass Ave onramp to I-90 WB in Boston

[thspfc]

14th Street ramp to WB I-94 in Hudson WI.

[TheHighwayMan3561]

Michigan St to northbound I-35 in Duluth, MN

TRUCK US 2/Winter St to westbound US 2 in Superior, WI (which really makes no sense as EB trucks on the Bong Bridge heading for this truck route then have to turn and drive several blocks *west* on Belknap Street to reach the truck route)

[TheStranger]

US 50 eastbound at Aerojet Road, Rancho Cordova. Somewhat redundant with the Hazel Avenue exit nearby
https://www.google.com/maps/@38.6288075,-121.2364093,14z

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Numerous examples on US 101 in California:

This one may or may not count: Whittier Boulevard (former US 101) onramp onto US 101 north (Santa Ana freeway), in Los Angeles - which technically may be part of the 7th Street interchange complex:
https://www.google.com/maps/@34.0368623,-118.2232476,17z

Another "may or may not count" - US 101 north (Santa Ana Freeway) to Spring Street in LA, if considered separate from the two ramps to Broadway:
https://www.google.com/maps/@34.056629,-118.245406,16z

US 101 (Hollywood Freeway) northbound exit for Barham Boulevard in Hollywood, ramp goes to East Cahuenga Boulevard (former US 101)
https://www.google.com/maps/@34.1251855,-118.3458493,17z

US 101 (Ventura Freeway) southbound exit for Ventura Road, Oxnard
https://www.google.com/maps/place/N+Ventura+Rd,+Oxnard,+CA/@34.2410025,-119.1897383,17z/data=!4m5!3m4!1s0x80e84c4d6706b0b7:0x2d174418f6fb22e1!8m2!3d34.2266188!4d-119.1944375

US 101 south at Carpinteria Avenue (former US 101), Carpinteria
https://www.google.com/maps/@34.4029308,-119.5388106,16z

US 101 north at Pueblo Street, Santa Barbara
https://www.google.com/maps/@34.4270591,-119.7264215,17z

Price Street onramp to US 101 south, Shell Beach
https://www.google.com/maps/@35.1545178,-120.6666694,17z

US 101 north (Bayshore Freeway) at Dore Avenue, San Mateo
https://www.google.com/maps/@37.5791902,-122.3216557,17z

US 101 south (Bayshore Freeway) exit for Paul Avenue (actually feeding into Mansell Street at San Bruno Avenue), San Francisco.  In the last 10 years CalTrans renamed the exit for northbound Bayshore Boulevard as "Paul Avenue" even though that was always part of the 3rd Street/Bayshore Boulevard exit complex, so not sure if this still counts.
https://www.google.com/maps/place/Mansell+St+%26+San+Bruno+Ave,+San+Francisco,+CA+94134/data=!4m2!3m1!1s0x808f7f1fe4023c1f:0xee48ed79aa491080?sa=X&ved=2ahUKEwjKhLnk4r_xAhVkHzQIHRIWBvsQ8gEwAHoECAYQAQ

US 101 north (Bayshore Freeway) at Vermont Street, San Francisco
https://www.google.com/maps/place/Vermont+St+%26+Mariposa+St,+San+Francisco,+CA+94107/@37.7634007,-122.4066025,17z/data=!3m1!4b1!4m5!3m4!1s0x808f7e339e692669:0x622c6fc3e938efe1!8m2!3d37.7634007!4d-122.4044138

US 101 north (Redwood Highway) at Arata Lane, Windsor
https://www.google.com/maps/place/Arata+Ln,+California+95492/@38.5674873,-122.8346167,15z/data=!4m5!3m4!1s0x80841600e2c3d121:0x270f0d35d633b7e6!8m2!3d38.5619927!4d-122.8106681


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Not built yet, but planned already on a newer road: Santa Mesa Bridge (G. Araneta Avenue) onramp for Metro Manila Skyway northbound, in San Juan/Quezon City.  No corresponding southbound ramp slated for this spot:
https://www.openstreetmap.org/search?query=N.%20Domingo%20%26%20G.%20Araneta#map=18/14.60354/121.02053

[jakeroot]

The WA-99 Freeway in South Seattle has a single northbound on-ramp from S Cloverdale Street:

https://goo.gl/maps/aaNFHXpFQiX2ZQRQ7

The closest parallel off-ramp is to 5th & Kenyon, seven blocks north-north-west.

[skluth]

San Diego has two consecutive exit ramps on NB CA 163 in Balboa Park going to Balboa Dr and Richmond St respectively.