Longest on/off ramps

[CtrlAltDel]

I-95 South to I-595 West: 3.2 miles on a lane that's longer than some entire 3dis. (Once you take Exit 26, you can't return to I-95.)

Back in the days before GPS, I once tried to access 595 from 736, but I was not able to, and so I had to travel down a bit further and double back. Now I know why.

[Occidental Tourist]

The longest offramps in SoCal:

The Firestone Blvd offramp from the 605 n/b is 9/10ths of a mile long. 
The Century Blvd offramp from the 405 n/b is 1.1 miles long.
The La Cienega Blvd offramp from the 405 n/b is 1.2 miles long.
The Imperial Highway e/b offramp from the 405 s/b is 1.6 miles long.
KPCC's Offramp radio program is 49 minutes long.

[TheStranger]

Some long NorCal examples:

Alemany Maze, San Francisco
- US 101 north to I-280 north/I-280 south to US 101 south, about 0.8 mile
https://www.google.com/maps/dir/37.7256378,-122.4018352/37.7365759,-122.4035067/@37.7331256,-122.4089485,18z/data=!4m2!4m1!3e0
- US 101 north to I-280 south (in the same ramp complex)
https://www.google.com/maps/dir/37.7256378,-122.4018352/37.7336216,-122.41176/@37.7281875,-122.4158139,15z/data=!4m2!4m1!3e0

- I-280 north to Cesar Chavez (Army) Street. 0.6 miles long
https://www.google.com/maps/dir/37.7430685,-122.3967389/37.7498776,-122.3923004/@37.7430069,-122.3970986,20z/data=!4m9!4m8!1m5!3m4!1m2!1d-122.3967457!2d37.7430994!3s0x808f7faa33bcac13:0xa42eadb57840c4f4!1m0!3e0

San Francisco International Airport
- US 101 south to SFO, 1.9 miles
https://www.google.com/maps/dir/37.6373054,-122.4046866/37.6145443,-122.3928695/@37.6303659,-122.4176733,15z/data=!4m9!4m8!1m5!3m4!1m2!1d-122.4037029!2d37.6334908!3s0x808f79d31ba90a0f:0xfc0c1949e1a98bf!1m0!3e0
- I-380 east to SFO (shared with above ramp), 2 miles
https://www.google.com/maps/dir/37.6338166,-122.4109707/37.6145443,-122.3928695/@37.6266534,-122.4128968,15z/data=!4m9!4m8!1m5!3m4!1m2!1d-122.4041392!2d37.633247!3s0x808f79d266a7ba49:0xe2c10341702ba369!1m0!3e0
- SFO to I-380 west, 2 miles
https://www.google.com/maps/dir/37.6147596,-122.393454/37.6342734,-122.4115633/@37.5825502,-122.4255815,15z/data=!4m2!4m1!3e0

- I-280 south to San Bruno Avenue, 0.7 miles
https://www.google.com/maps/dir/37.6317857,-122.4369861/37.6241043,-122.4288966/@37.6275032,-122.4347545,16z/data=!4m2!4m1!3e0

- I-680 south to US 101 south in San Jose, 1.4 miles
https://www.google.com/maps/dir/37.3442738,-121.8454671/37.3295925,-121.8424148/@37.3440666,-121.8450287,17z/data=!4m2!4m1!3e0

- I-80 east to I-880 south (MacArthur Maze) in Oakland, 1.6 miles.
https://www.google.com/maps/dir/37.8232347,-122.3169174/37.8156239,-122.2998573/@37.8334997,-122.3541215,14z/data=!4m2!4m1!3e0

- Route 92 east to I-880 north in Hayward, 1.2 miles
https://www.google.com/maps/dir/37.6346492,-122.1040562/37.6473967,-122.0954848/@37.6349005,-122.1002164,17z/data=!4m2!4m1!3e0

- I-238 west to I-880 south, San Lorenzo, 1.2 miles
https://www.google.com/maps/dir/37.6897775,-122.1198918/37.68547,-122.1307131/@37.6895012,-122.1313276,16z/data=!4m2!4m1!3e0

[cwf1701]

Some from Metro Detroit:

I-75 to US-24 (Telegraph exit 35) 1.5 miles https://www.google.com/maps/dir/42.1860214,-83.2433016/42.194183,-83.2669105/@42.1907768,-83.2627532,15.5z/data=!4m2!4m1!3e0?hl=en

I-94 to M-3 (Gratiot Exit 231) 0.6 miles https://www.google.com/maps/dir/42.5190415,-82.9170189/42.5278737,-82.9164124/@42.5254528,-82.9213739,16.5z/data=!4m2!4m1!3e0?hl=en

I-75 to M-3 (Gratiot Exit 51B via northbound I-75) 0.7 Miles https://www.google.com/maps/dir/42.3412948,-83.0494744/42.3461043,-83.0369197/@42.3450622,-83.0423805,16.75z/data=!4m2!4m1!3e0?hl=en

A former on ramp is I-94 at M-59 (Hall Rd) The on ramp was replaced in the 90s with a shorter on ramp for WB-94. Before I-94, it was a part of M-29. The remains of the old on ramp is here: https://www.google.com/maps/@42.6261992,-82.8576826,1097m/data=!3m1!1e3?hl=en

[Joe The Dragon]

I-90 to I-55 north in Chicago is long.


https://www.google.com/maps/dir/41.8572844,-87.644388/41.8473593,-87.6323815/@41.8511685,-87.6418855,1362m/data=!3m1!1e3

other way is just as long

https://www.google.com/maps/dir/41.8475243,-87.6318523/41.8554742,-87.6443616/@41.8523112,-87.6424693,1668m/data=!3m1!1e3!4m2!4m1!3e0

[ftballfan]

NB I-75 to WB I-69 in Flint is another long one

[Tom958]

GA 316 to Pleasant Hill Road, 2.2 miles.

[TheStranger]

Long SoCal ramps (excluding one mentioned in the 2015 thread, the Route 55/I-5 connector)

1 mile, I-405 south to I-710 north in Long Beach
https://www.google.com/maps/dir/33.8251333,-118.2182979/33.8345421,-118.208551/@33.8323925,-118.2211637,16z/data=!4m2!4m1!3e0

1.1 miles, I-110 north to I-10 west in Los Angeles
https://www.google.com/maps/dir/34.0329651,-118.2745082/34.037834,-118.280996/@34.0368182,-118.2746151,17z/data=!4m2!4m1!3e0

1.1 miles, I-405 south to Route 22 west near Seal Beach
https://www.google.com/maps/dir/33.7863615,-118.093945/33.7744061,-118.0954916/@33.7824321,-118.0923588,17z/data=!4m2!4m1!3e0

1.4 miles, Route 22 east to I-405 north
https://www.google.com/maps/dir/33.7742163,-118.0939523/33.7881844,-118.0959757/@33.7812647,-118.0913301,17z/data=!4m2!4m1!3e0

1.8 miles, Route 91 west in Carson to I-405 north in Gardena via I-110 south
https://www.google.com/maps/dir/33.8727822,-118.2739738/33.85906,-118.2890761/@33.863992,-118.2858717,16z/data=!4m2!4m1!3e0

[SSR_317]

I-865 

Also in Indianapolis, I-70 E to I-74/465 E. It's 1.3 miles between the last entrance from the ramp to I-70 E and the split between the I-465 directions.

miles
Sorry, it's MUCH longer than that - 3.48 miles from the Gore Point of EB exit 69 to the Gore Point of the split where you can access the remainder of the ramps - to either Northbound I-465 (increasing Reference Post direction) and Westbound I-74 or Southbound I-465 (decreasing Reference Post direction) and Eastbound I-74.

[SkyPesos]

I-865 

Also in Indianapolis, I-70 E to I-74/465 E. It's 1.3 miles between the last entrance from the ramp to I-70 E and the split between the I-465 directions.

miles
Sorry, it's MUCH longer than that - 3.48 miles from the Gore Point of EB exit 69 to the Gore Point of the split where you can access the remainder of the ramps - to either Northbound I-465 (increasing Reference Post direction) and Westbound I-74 or Southbound I-465 (decreasing Reference Post direction) and Eastbound I-74.

I forgot about the points past the I-465 directional split 
If you count from the same starting point I had (gore of last entrance ramp to I-70 E), to where it merges with I-465 N, that will be 2 miles. Here's why I started measuring from the last I-70 E entrance ramp instead of from the gore of Exit 69:

4: Any C/D road needed to get to/from the ramp does not count in the final distance. A C/D road is any ramp that, one you exit, you have a choice to merge back onto the road you just exited. No exceptions here.

[SectorZ]

1.7 miles off I-93 coming into Boston. Even has its own wikipedia page.

https://en.wikipedia.org/wiki/Leverett_Circle_Connector_Bridge

[kurumi]

I-84 WB to I-384 EB in Manchester, CT, is 1.8 miles. There are C/D ramps in that complex, but this is not one of them; you cannot get back to I-84

[OCGuy81]

What about in Milwaukee, from College Ave, you the ramp to I-43/41/894 is about 2.55 miles from College Ave until you're on the main lanes of 43/41/894.

[SSR_317]

I-865 

Also in Indianapolis, I-70 E to I-74/465 E. It's 1.3 miles between the last entrance from the ramp to I-70 E and the split between the I-465 directions.

miles
Sorry, it's MUCH longer than that - 3.48 miles [note: later corrected to 3.4458 miles - see reply below] from the Gore Point of EB exit 69 to the Gore Point of the split where you can access the remainder of the ramps - to either Northbound I-465 (increasing Reference Post direction) and Westbound I-74 or Southbound I-465 (decreasing Reference Post direction) and Eastbound I-74.

I forgot about the points past the I-465 directional split 
If you count from the same starting point I had (gore of last entrance ramp to I-70 E), to where it merges with I-465 N, that will be 2 miles. Here's why I started measuring from the last I-70 E entrance ramp instead of from the gore of Exit 69:

4: Any C/D road needed to get to/from the ramp does not count in the final distance. A C/D road is any ramp that, one you exit, you have a choice to merge back onto the road you just exited. No exceptions here.

I would argue with "rule 4", because in this situation drivers have NO OTHER OPTION but to use Exit 69 if they want to get from EB I-70 to I-465/I-74. While it is true that vehicles taking exit 69 CAN merge back onto EB I-70 from this C/D (for traffic that entered it from Ameriplex Pkwy), there is no other exit point from the EB mainline until subsequent exit 75's ramp to EB Sam Jones Expwy (Raymond St). Thus, I believe the entire length of this "pseudo C/D" should count as part of these ramps.

BTW, I have seen a fool dangerously exit mainline I-70 and dart across the 2 re-entering lanes of the C/D in order to get to the I-465/I-74 ramps he missed back at Exit 69. The right median barrier openings and paved shoulders that exist at that point can sadly facilitate this reckless movement as there are no roadway structures present to prevent it. IMHO this was poor design, but I can see why it occurred.

Regardless, here are the calculations I came up with (all distances cumulative):
     Feet            Miles          Point
        0          0.0000       Gore Point on EB-70 for Exit 69 (right 2 lanes become a Collector/Distributor)
  1,605          0.3040       under G/S (Grade Separation) for Ramp from EB-I-70 to IND Airport (accessed from Exit 68)
  3,036          0.5750       Merge (Reverse Gore Point) with Ramp from Ameriplex Pkwy (2 lanes added from Right - C/D now 4 lanes wide)
  3,656          0.6924       [on separate Ramp to the Left from IND Airport] Gore Point between Ramp to EB I-70 & Ramp to the C/D
  5,047          0.9559       Left Reverse Gore Point of Ramp from IND Airport (2 lanes added from Left - C/D now 6 lanes wide)
  5,486          1.0390       C/D Lane #6 drops (end striping)
  6,546          1.2398       C/D Lane #6 ends
  6,676          1.2644       Dynamic Message Sign (DMS) over C/D lanes #2 thru #4
  8,323          1.5763       C/D Lane #5 drops (end striping)
  9,240          1.7500       C/D Lane #5 ends
10,022          1.8981       [future] C/L for G/S undercrossing of proposed IND Airport taxiway
11,417          2.1623       Right Median Barrier ends (between EB mainline & parallel C/D)
11,568          2.1909       Gore Point: Ramp to I-465/I-74 = lanes #3 & #4 leave C/D (lanes #1 & #2) on the Right
12,548          2.3765       [on EB I-70 mainline] Merge of C/D - add Mainline Lane #4 & Lane #5 on the Right
12,692          2.4038       Right Median Barrier resumes (between EB mainline & parallel ramp to I-465/I-74)
14,158          2.6814       I-70 Reference Post 72 (on barrier between EB mainline & parallel ramp)
17,673          3.3472       under G/S at C/L (centerline) of High School Rd
18,194          3.4458       Gore Point on Ramp to I-465/I-74: Ramp Lanes #1 & #2 to NB I-465/WB I-74; Ramp Lane #3 to SB-I-465/EB I-74
                                      [on Ramp to NB I-465/WB I-74 (2 lanes)]
18,194          3.4458       Gore Point for Ramp to SB I-465/EB I-74 (Ramp Lane #3 leaves to Right)
19,183          3.6331       above I-465 (at C/L) on G/S
19,799          3.7498       above C/L of Box Culvert for drainage channel
20,112          3.8091       under C/L of EB I-70 on G/S above
20,164          3.8189       C/L of I-70 above (theoretical)
20,210          3.8277       under C/L of WB I-70 on G/S above
20,234          3.8322       under Loop Ramp [WB I-70 to SB I-465] above (common G/S with WB I-70)
20,948          3.9674       past (barrier protected) IND Airport Landing Light Beacon for Runway 32 (to Right, between this ramp and Ramp from WB I-70 to NB I-465)
21,354          4.0443       Merge with Ramp from WB I-70 (add Ramp Lane #3 on the Right)
21,791          4.1271       Ramp Lane #3 drops (end striping)
22,104          4.1864       Ramp Lane #3 ends
22,398          4.2420       Left Merge onto mainline NB I-465/WB I-74; add Mainline Lanes #5 & #6 on the Right)
                                      [on Ramp to SB I-465/ EB I-74 (1 lane)]
18,194          3.4458       Left Gore Point for Ramp to NB I-465/WB I-74 (Ramp Lanes #1 & #2 leave to Left)
19,398          3.6739       Left Merge with Loop Ramp from WB I-70; add Ramp Lane #1 to Left (Ramp now 2 lanes wide)
20,177          3.8214       Left Merge onto mainline SB I-465/EB I-74: add Mainline Lanes #4 & #5 on the Right)

These figures were obtained from detailed analysis of Google Maps images.

[cpzilliacus]

This reminded me of another one: MD 2 SB to I-695 EB south of Baltimore - large enough that a shopping center is inside the cloverleaf!

The opposite movement is also quite long - Inner Loop I-695 to MD-2 north requires a very early exit and results in a ramp that is about 1.3 miles long.

[roadman65]

The FL TOLL 417 to US 17 & 92 ramp in Sanford, FL is very long as that used to be the north terminus of FL 417.  It also features a shopping center within it.
https://www.google.com/maps/@28.775077,-81.2842455,15.15z

[jakeroot]

The longest regular on-ramp (from a non-freeway road) that comes to mind in the South Puget Sound region of Washington State is the southbound onramp to I-5 from Marvin Road (the new DDI) in Lacey, just outside Olympia.

It is not shown on Google Maps, as the satellite imagery is just barely too old. But you can see the shape of the ramp here, including what will be a RIRO into the shopping center to the north.

It is designed as a collector road, but currently operates as a regular on-ramp while other ramp connections remain unbuilt. The on-ramp doesn't merge onto southbound I-5 until right about here. About 1.3 miles. Long enough that you see people overtaking each other, as it's two lanes until right before the merge.

[dlsterner]

This reminded me of another one: MD 2 SB to I-695 EB south of Baltimore - large enough that a shopping center is inside the cloverleaf!

The opposite movement is also quite long - Inner Loop I-695 to MD-2 north requires a very early exit and results in a ramp that is about 1.3 miles long.

It also produces the anomaly of the exit numbers appearing in the order:  1  3  2  4  when heading westbound from the Key bridge.

[doorknob60]

I-84 EB to US-93 SB near Twin Falls, ID is 1.5 miles long. Map

[wriddle082]

I-77 Exit 1 (SB only exit) to US 21/176/321 (Charleston Hwy.) in Cayce, SC.  It flies directly over the I-26/I-77 junction and past the southern terminus of I-77 to reach Charleston Hwy and Fish Hatchery Rd at a 4-way traffic signal.  I'd say the whole ramp is at least a mile.

Some might say this ramp would make a good southern extension of I-77 in the general direction of Savannah, but the heavy residential areas directly past this ramp on Fish Hatchery Rd would very much disagree.  As would I, since my neighborhood is a few miles off of Fish Hatchery.

The on-ramp from this intersection back to I-77 north is a bit shorter, as it is straighter and it meets the ramp from I-26 east before meeting the ramp from I-26 west.  So only the Exit 1 off-ramp qualifies.

[CtrlAltDel]

The ramp from I-57 N to I-294 N is 2.0 miles long.

Also, the ramp from I-290/IL-53 N to I-90 W extends 2.2 miles.

The Illinois Tollway has been making ramps longer and longer (but not specifically because of the tolls, so I find them worthy of mention).

[webny99]

The ramp from I-57 N to I-294 N is 2.0 miles long.

Also, the ramp from I-290/IL-53 N to I-90 W extends 2.2 miles.

For these examples, along with several others that have been mentioned, I'm not sure I'd really call it a ramp for its full length. More like a ramp that joins or forms a service or C/D road and then parallels the freeway for a while before joining.

[thenetwork]

In Ohio, one of the longest on-ramps that jogs in my mind is from CR-18/Mahoning Avenue to the Ohio Turnpike/I-76 East /I-80 West near Youngstown.  From EB Mahoning to EB I-76, the total "ramp" mileage is +/- 2.2 miles.

This also counts when the Mahoning ramp merges into the free I-76 on-ramp to the Turnpike toll plaza, and the ramp from the toll plaza to the EB mainline Turnpike.

https://www.google.com/maps/place/Youngstown,+OH/@41.1072688,-80.8357521,14.84z/data=!4m5!3m4!1s0x8833e1d16893bc9f:0x5d2c726a0cccf044!8m2!3d41.0997803!4d-80.6495194

[bing101]

http://www.gribblenation.org/2019/07/california-state-route-244-and-un-built.html?m=1
I-80 to CA-244 gets viewed as the longest freeway ramp in the Sacramento area at 1.08 miles long.
However this ramp was originally planned to be part of a proposed now cancelled of the Beltline freeway extension.

[formulanone]

I-95 South to I-595 West: 3.2 miles on a lane that's longer than some entire 3dis. (Once you take Exit 26, you can't return to I-95.)

Back in the days before GPS, I once tried to access 595 from 736, but I was not able to, and so I had to travel down a bit further and double back. Now I know why.

The original ramp was a little shorter, but blocked off I-595 access from SR 736. The ramps were modified again in 1993-94 which allows southbound access to I-95 and to I-595, which would knock off a few tenths from that long ramp. There's no way to get back into I-95 south without reversing (though once I was directed to make a U-turn up the Davie Road ramp and avoid a mess).