Most mainline switches (exiting off itself) for a numbered freeway route?

[TheStranger]

What I mean exactly:

There are instances where a numbered (freeway) route changes alignments significantly such that one has to stay on the right to continue on the numbered route, with the through route (of at least two lanes continuing on) on the left side being another number entirely.  (Or when one freeway segment terminates at another in the other direction, one essentially joins another numbered route from the right side)

I'm not sure if a fully-directional Y would count for this, but a semi-directional Y (as in the forthcoming example of I-5 off of US 101) absolutely does.

i.e. for I-5, mainline switches occur at the following junctions:

I-805 in the La Jolla area of San Diego (I-5 exits off of itself while the through lanes from the north continue as 805 going southbound)
US 101 in East Los Angeles (the Santa Ana Freeway - which used to be US 101 both north and south of the interchange - continues as the through lanes, while I-5 exits along the Golden State Freeway)
Route 99 in Wheeler Ridge (I-5 exits to use the West Side Freeway while 99 continues north on the Golden State Highway corridor and used to continue south as well)
I-580 in Vernalis (I-580 was planned as I-5W though so this only became a switch when the western branch of 5 was renumbered)
I-405 in Portland (the left through lanes continue to 405 and Harbor Drive)

for I-80, this phenomenon occurs at:

the Macarthur Maze at 880/580 (eastbound lanes merge onto the right side of what was once the through lanes for Route 17, westbound lanes exit off of the right)
US 50 in West Sacramento (80 uses the right-side ramps on both directions for what used to be 880; prior to this, the mainline switch occurred at Route 99/US 50 in Sacramento's Oak Park area, where Business 80 now exits off of itself while 50 continues on)
I-15 in Salt Lake City (the concurrency with 15 requires 80 traffic in both directions to stay to the right)
I-76 in Big Springs, Nebraska (through traffic from the east continues west onto what was former I-80S/current I-76, and 80 eastbound traffic merges onto the right side of the end of 76)
I-35/I-235 in West Des Moines (I-80 traffic continues on right-hand ramps to I-35 north, while mainline lanes become I-235)
I-280/I-74 in Colona, Illinois (the infamous I-74/I-80 cloverleaf)
I-294 in Markham, Illinois (from the 80/294 concurrency going west, 80 exits on the right and enters the multiplex on the right as well)
I-90 in Lake Station, Indiana
I-76 in Jackson Township, Ohio (where 80 leaves the Ohio Turnpike)
I-280 in Parsippany, New Jersey

[bugo]

I-44 in OKC exits off itself several times.

[FreewayDan]

There's about three mainlane switches for I-10.  One is north of the East L.A. interchange where it meets with I-5 (eastbound I-10 exits I-5 while westbound I-10 merges into I-5 South).  Two are in San Antonio: first with the IH 35 junction northwest of downtown San Antonio and second at the I-10 interchange with I-35 and U.S. 90.

[The Premier]

I-76 in Jackson Township, Ohio (where 80 leaves the Ohio Turnpike)

I-76 exits itself 2 additional times, each at the Kenmore Leg. I-77 exits itself at the Central Interchange to meet up with I-76 WB

[okroads]

I-44 in OKC exits off itself several times.

I-35 also exits off itself in OKC, but only once compared to I-44's 3 times it exits itself in the OKC metro alone.

[huskeroadgeek]

I-280/I-74 in Colona, Illinois (the infamous I-74/I-80 cloverleaf)

This is one of the oddest and most annoying ones because both I-80 and I-74 exit off themselves. I've long thought that the interstates in the Quad Cities shuld be numbered differently to avoid this. I plan my route going through there in order to avoid having to take an exit-if I am taking I-80 towards Chicago, I take I-280 around the Quad Cities so that I can just go straight at that interchange, and if I am taking I-74 towards Peoria, I stay on I-80 around the Quad Cities so that I can go straight into I-74 at the interchange.

[mukade]

Depending on your definition, I'd say I-72 exits itself 3 times - at I-172, and twice at I-55. Eastbound I-72 on the south side of Springfield merges into I-55, but westbound is more of an exit off I-55. Similarly, westbound I-72 exits itself at exit 4 (I-172).

[RustyK]

I know I-15 when it follows the I-90 roadway for a while does this - each direction has to "exit" to stay on I-15 -- that "exit" is an exit number for I-15 itself!  At the I-90/94 spilt east of Billings, the same thing occurs:  I-90 is an exit for itself, exit 455, while I-94 just continues straight ahead.  (I-90 is exit 0 on westbound 94)

[TheStranger]

I-280/I-74 in Colona, Illinois (the infamous I-74/I-80 cloverleaf)

This is one of the oddest and most annoying ones because both I-80 and I-74 exit off themselves. I've long thought that the interstates in the Quad Cities shuld be numbered differently to avoid this. I plan my route going through there in order to avoid having to take an exit-if I am taking I-80 towards Chicago, I take I-280 around the Quad Cities so that I can just go straight at that interchange, and if I am taking I-74 towards Peoria, I stay on I-80 around the Quad Cities so that I can go straight into I-74 at the interchange.

There are several inelegant solutions (one that I thought of is to extend 88 along what is now I-80 on the north side, have 80 replace 280, and 74 remain on its existing alignment) and one that was proposed but not used (switching 280 and 80).  But the absolute best solution - which would avoid ALL mainline switches - would be simply having 280 replaced by 80, and 74 replacing 80 on the north side!  

It's very political - I think 74 running straight through the Quad Cities when it doesn't serve as a through connection from the rest of 74 in the first place is evidence of that.

[golden eagle]

I-55 in Memphis does this. You have to get in the exit lane to stay on 55, while the left lanes proceed to Riverside Drive. I-10 at Slidell does the same thing.

[xcellntbuy]

Some other possible candidates:

Interstates 87 and 90 at Exit 24 of the New York State Thruway as well as Exits 1E-W and 1N-S of the Adirondack Northway and the Northside Arterial, respectively.
Interstate 90 at Exit B1 of the Berkshire Spur of the same Thruway
Interstates 93 and 95 south of Boston due to the fact that Interstate 95 was never completed into downtown Boston.
Interstate 95 in metropolitan Washington, DC, both in Maryland and Virginia on the National Capital Beltway
Interstates 76 and 80 on the Ohio Turnpike
Interstate 76 from the Pennsylvania Turnpike to the Schuykill Expressway

[huskeroadgeek]

I-280/I-74 in Colona, Illinois (the infamous I-74/I-80 cloverleaf)

This is one of the oddest and most annoying ones because both I-80 and I-74 exit off themselves. I've long thought that the interstates in the Quad Cities shuld be numbered differently to avoid this. I plan my route going through there in order to avoid having to take an exit-if I am taking I-80 towards Chicago, I take I-280 around the Quad Cities so that I can just go straight at that interchange, and if I am taking I-74 towards Peoria, I stay on I-80 around the Quad Cities so that I can go straight into I-74 at the interchange.

There are several inelegant solutions (one that I thought of is to extend 88 along what is now I-80 on the north side, have 80 replace 280, and 74 remain on its existing alignment) and one that was proposed but not used (switching 280 and 80).  But the absolute best solution - which would avoid ALL mainline switches - would be simply having 280 replaced by 80, and 74 replacing 80 on the north side!  

It's very political - I think 74 running straight through the Quad Cities when it doesn't serve as a through connection from the rest of 74 in the first place is evidence of that.

I like the idea of 74 replacing 80 on the north side and 80 replacing 280 on the south side. Then the portion of 74 between 80 and 280 could be given the 280 number. That portion of highway really is more suited for a 3di anyway. It really is more of a local route that serves the downtown areas of Bettendorf and Moline rather than a through route for I-74 traffic. Ideally, I-74 should end at that interchange. Then the remaining portion of I-74 could be another x80-I guess it would have to be I-880 though since 480 and 680 are already in use in Iowa. You're probably right about politics-there's no other logical reason why I-74 shouldn't end at that interchange.

[TheStranger]

Interstate 95 is the one route I think does this quite a bit:

- possibly at the I-10 junction in Jacksonville
- I-295 north of Richmond (I would guess this was introduced when the proposal to reroute 95 on 295 existed)
- I-495 in Virginia (southbound, this has become a left-hand continuation, but it may have been a true all-right-exit switchover at one point)
- I-495 in Maryland (I think this may have been intended as a southbound left exit even before 95 into DC was canceled)
- I-895 in Rosedale, Maryland north of Baltimore
- I-276 in metro Philadelphia (once constructed)
- New Jersey Turnpike in Mansfield Township, New Jersey
- I-80 in Fort Lee, New Jersey
- not sure if I-395 in Groton, Connecticut counts (as I-95 continues southbound along left side)
- I-93/Route 128 in Dedham, Massachusetts
- Route 128 in Peabody, Massachusetts
- formerly at I-495 in Portland, MA

[bugo]

I-55 in Memphis does this. You have to get in the exit lane to stay on 55, while the left lanes proceed to Riverside Drive. I-10 at Slidell does the same thing.

It exits off itself twice in Memphis: at Riverside and at I-240.

[bugo]

I-44 in OKC exits off itself several times.

I-35 also exits off itself in OKC, but only once compared to I-44's 3 times it exits itself in the OKC metro alone.

Do you know the history behind I-44 between I-35 and I-40?  I know it was once I-240.  It appears to be several highways haphazardly tied together.

[froggie]

I-55 in Memphis does this.

Twice, as bugo noted.

I-10 at Slidell does the same thing.

As the OP defined it, yes.  Though this one's arguable, given that the 10/59 split going north/eastbound is designed as a major route split...it's not really an exit ramp per se.

Interstate 95 in metropolitan Washington, DC, both in Maryland and Virginia on the National Capital Beltway

Not anymore in Virginia.  Maryland is arguable, as southbound is designed as a through-route continuation, while northbound you have a "major split" where it breaks off the Outer Loop and a "major merge" where the ramp from the Inner Loop merges.

- I-495 in Virginia (southbound, this has become a left-hand continuation, but it may have been a true all-right-exit switchover at one point)

It was, prior to the Springfield Interchange makeover.

- I-495 in Maryland (I think this may have been intended as a southbound left exit even before 95 into DC was canceled)

Actually, no.  The original configuration had only the loop ramp which now serves as the southbound connection to US 1.  The current southbound 95 flyover was built sometime in the '80s, well after the DC cancellation.

- I-895 in Rosedale, Maryland north of Baltimore

Not anymore.

[okroads]

I-44 in OKC exits off itself several times.

I-35 also exits off itself in OKC, but only once compared to I-44's 3 times it exits itself in the OKC metro alone.

Do you know the history behind I-44 between I-35 and I-40?  I know it was once I-240.  It appears to be several highways haphazardly tied together.

I-44 through OKC is a couple of different highways tied together; from the northern terminus of the H.E. Bailey Turnpike to I-240 was originally just U.S. 62, then from present-day I-240 (Exit 115) to I-40, present-day I-44 was part of I-240. North of I-40, it was originally I-440, and the part between OK 66 & I-35 was originally just U.S. 66. All of this route was changed to I-44 in 1982.

[bugo]

I-44 through OKC is a couple of different highways tied together; from the northern terminus of the H.E. Bailey Turnpike to I-240 was originally just U.S. 62, then from present-day I-240 (Exit 115) to I-40, present-day I-44 was part of I-240. North of I-40, it was originally I-440, and the part between OK 66 & I-35 was originally just U.S. 66. All of this route was changed to I-44 in 1982.

I-44 was extended for Oklahoma's 75th anniversary celebration.  Oklahoma has a weird way of celebrating its birthdays. For the centennial celebration, ODOT changed from the circle to the meat cleaver.  I wonder what they'll do in 2032.

[TheStranger]

I-44 through OKC is a couple of different highways tied together; from the northern terminus of the H.E. Bailey Turnpike to I-240 was originally just U.S. 62, then from present-day I-240 (Exit 115) to I-40, present-day I-44 was part of I-240. North of I-40, it was originally I-440, and the part between OK 66 & I-35 was originally just U.S. 66. All of this route was changed to I-44 in 1982.

I-44 was extended for Oklahoma's 75th anniversary celebration.  Oklahoma has a weird way of celebrating its birthdays. For the centennial celebration, ODOT changed from the circle to the meat cleaver.  I wonder what they'll do in 2032.

Let me guess, the Gilcrease Expressway will be completed?

[TheStranger]

Some more California examples, with I-5's four (805, 101, 99, 580) probably taking the cake:

I-580:
I-80 in Richmond (became a right-exit instead of a directional Y in 1997)
I-238/Route 238 in Castro Valley
formerly at I-205 near Mountain House until 2009 (became a directional Y, was built semi-directional; semi-directional ramp to right-side of road is now truck ramp; US 50 continued east and west of this interchange on the mainline)

Route 99's three are all located in Sacramento:
US 50/Business 80 at the Oak Park interchange (US 99E used to continue directly north on the mainline that connects Route 99 with Business 80)
I-5 in downtown
I-5 in Natomas near the airport

---

Some more national examples:

I-15:
formerly at Route 163 (I assume this was changed up when the historic Kearny Villa Road/former US 395 alignment was bypassed in the early 80s)
I-215 at Devore (US 395 continued on mainline in both directions with today's I-15/originally planned Route 31 exiting from the right southbound and entering from the right northbound; and at one point the mainline was I-15 or I-15E until 1982)
I-84 in Tremonton, Utah
I-90 in Ramsay, Montana (west of Butte)
I-90 in Butte, Montana


I-40:
I-35 in Oklahoma City
(was I-240 in downtown Memphis ever built as such, or was it built with the mainline feeding into the north beltway half with the connection to Sam Cooper Boulevard already canceled?)
I-240 in eastern Memphis (though could this be considered a directional interchange with the left exit, and thus not a true mainline switch?  I suspect this left exit was around even when 40 was on Sam Cooper)
I-65 in Nashville
I-73 in Greensboro (was originally not at all a switch until the beltway construction began, and then 40 was returned to its through-town alignment but now exiting off itself)
I-85 in Greensboro (see note for I-73)
I-85 in Hillsborough, North Carolina
(was there ever one at Wade Avenue in Raleigh near the RBC Center?)

I-70:
I-55/I-64/US 40 in St. Louis
I-55 in Troy, Illinois
I-65 (northeastern split) in Indianapolis
I-670 in Columbus
I-71 in Columbus
I-76 in Youngwood, Pennsylvania
I-76 in Breezewood  
US 30 in Breezewood  

Western I-84:
ramps for I-205 (was planned as I-80N) in Portland
I-86 in Rupert, Idaho (US 30 remains on mainline both west and east of the interchange)
I-15 in Ogden

I-90:
I-94 in Billings, Montana
(formerly at today's I-290 in Rolling Hills, Illinois and in Chicago)
North-south spur to Cermak Road at I-55 in Chicago
I-94 at the Chicago Skyway
I-80 in Elyria, Ohio
I-71 in Cleveland
I-271 in Wickliffe, Ohio
I-87 in Albany
Berkshire Thruway southeast of Albany

I-74:

I-280 near Quad City International Airport in Illinois (US 6 continues on mainline)
I-80 in Colona, Illinois
I-55 in Springfield
I-465 in Speedway, Indiana
I-465 in Beech Groove, Indiana

[UptownRoadGeek]

I-10 in Baton Rouge exits itself as the mainline becomes I-12, at the New Orleans line it exits itself as the mainline becomes I-610, 3 miles later it exits itself again as the mainline becomes U.S. 90 Business, once in Slidell it exits itself one more time at the interchange with I-59.

[Brandon]

I-294 in Markham, Illinois (from the 80/294 concurrency going west, 80 exits on the right and enters the multiplex on the right as well)

I-80 exits here, not I-294.  I-294 (Tri-State Tollway) is the mainline.  Currently, it functions more as a split than an exit.

I-90 in Lake Station, Indiana

No, I-80 does the exiting here, not I-90.

[Chris]

Isn't this called a "TOTSO" (Turn Off To Stay On)?

[Brandon]

I-90:
(formerly at today's I-290 in Rolling Hills, Illinois and in Chicago)
North-south spur to Cermak Road at I-55 in Chicago
I-94 at the Chicago Skyway

The Cermak Spur is an exit off I-90 and I-94.  The two split further north at the Edens Junction.

I-74:
I-55 in Springfield

That's Bloomington-Normal, not Springfield.  The north junction (Exit 163) functions this way.  The south one is a split.

[Brandon]

I-72 does this on the east side of Springfield, IL.  The reason is that is was originally the end of I-72.
I-39 did for a while twice in Rockford.  Once at the I-39/US-20 interchange (still does) and once at the I-39/I-90 interchange.  The latter was recently turned into a split.
I-94 exits I-80 in South Holland, IL (Exit 160).