2di Interstates with single lane portions.

[Troubleshooter]

One of the most blatant of these is I-76 at its interchange with I-80 near Youngstown Ohio. I-76 follows single lane ramps. One direction uses two loop ramps.

I-80 at Portage Indiana follows single lane exit ramps, one being a loop ramp.

Richmond Virginia I-64 westbound has a single lane merge with I-95.

Collinsville Illinois I-55 northbound has a single lane ramp to merge with I-70.

East St. Louis IL I-64 has single lane merge and diverge where it joins I-70 and I-55.

But in St. Louis, I-55 and I-70 have the single lane merge and diverge where they join I-64.

[Duke87]

There are countless examples involving entrance/exit ramps. But a couple come to mind that are, in fact, sections of two-lane interstate highway:

- I-93 through Franconia Notch
- I-81 on the Thousand Islands Bridge


The tunnels on the PA Turnpike would be former examples. As would I-95 in northern Maine.

[vdeane]

I think those two are the only "true" two-lane 2dis.  IMO, using ramps for this is cheating!

[agentsteel53]

I-8 drops to a single lane eastbound at I-5, but that is a ramp.

I-70 used to be two lanes west of Green River through the San Rafael area in Utah. 

[exit322]

77/64 on the WV Turnpike is a former example as well.

[bugo]

I-40 westbound in North Little Rock narrows down to one lane near the I-30 interchange.  Also, I believe I-44 in OKC is one lane at at least one place.

[Grzrd]

I believe Alligator Alley was two lanes for many years, but I don't know if it had already been upgraded to four lanes when it was initially signed as I-75.

[Alps]

I believe Alligator Alley was two lanes for many years, but I don't know if it had already been upgraded to four lanes when it was re-designated as I-75.

Pretty sure it was.

[Zmapper]

I-80 Near Big Springs, NE is one lane EB during the merge with I-76.

[hbelkins]

In Wheeling, WV, all eastbound traffic on I-70 is shunted to a single lane approaching the tunnel.

In Knoxville, I-75 southbound is funneled to one lane as it merges with I-640.

[The Premier]

I-77 at the Central Interchange in Akron

[mightyace]

I remember that I-90 was two lanes through the Badlands of South Dakota back in 1972 and IIRC it was still signed.

Not surprisingly, sometime between then and now, it was 4-laned.

[andrewkbrown]

I-70's merge with I-79 in Washington, PA.

[jemacedo9]

I-83 N and S east of Harrisburg PA at the Eisenhower Interchange w/ I-283 and US 322

[Ian]

-I-95 northbound when it meets the south end of I-93 and merges onto MA 128 in Canton, MA.

-I-395 northbound where it leaves the Southeast Freeway in D.C.

[yakra]

I wanna say I-80 & I-74 where they bump near Quad Cities.

[SP Cook]

77/64 on the WV Turnpike is a former example as well.

To a degree.  The Turnpike was actually signed as "to I-77".  As parts were completed the regular 77 signs were put up.  However many maps, including RM, signed the road as 77.  It was never signed as 64, because the 64 was not connected from Lewisburg to Beckley until the year after the Turnpike was finally upgraded, and US 60 was the recomended alternate.

[Anthony_JK]

I-10 eastbound in Baton Rouge at the I-10/I-110 "Split" gets reduced to a one-lane "ramp"...which then converts into an auxillary ramp to exit at Washington Street.  Although, LaDOTD did recently tweak that interchange to allow for a smoother transition, the ramp itself remains one-lane.


Anthony

[Revive 755]

Collinsville Illinois I-55 northbound has a single lane ramp to merge with I-70.

Three things wrong with that statement:

1) I-70 merges with I-55 at Troy; I-255 crosses I-55/70 at Collinsville, but there is no merging of interstates.  Had the southern new Mississippi River bridge option been pursued, I-55 would have merged here.

2) As stated above, only I-70 traffic has to merge; Nothing really happens to traffic on I-55.

3) All the mainline interstate movements are two lanes.  Granted there are a few forced merges at that interchange that I'd like to see redone.
http://maps.google.com/maps?hl=en&ie=UTF8&ll=38.749925,-89.905919&spn=0.006359,0.020599&t=k&z=17

East St. Louis IL I-64 has single lane merge and diverge where it joins I-70 and I-55.

Nope, both I-64 movements there are two lanes, though the eastbound signage kind of makes the eastbound movement look like it has a lane drop for the NB IL 3 exit.

http://maps.google.com/maps?hl=en&ie=UTF8&ll=38.632804,-90.145317&spn=0.003185,0.0103&t=k&z=18


* I-55 has a couple single lane portions around Memphis:

- Both directions at the Crump cloverleaf in Memphis

- SB drops to a single lane briefly at the interchange with I-240:
http://maps.google.com/maps?hl=en&ie=UTF8&ll=35.072884,-90.029432&spn=0.000834,0.002575&t=k&z=20

* I-69 has/will have a single lane section each way at the interchange with I-55 south of Memphis

* I-72 is a single lane each way at the eastern interchange with I-55:
http://maps.google.com/maps?hl=en&ie=UTF8&ll=39.800183,-89.594635&spn=0.001566,0.00515&t=k&z=19

* I-74 has a bunch of single lane sections:

- At the merge with I-280 around Quad Cities (I think there are plans to fix the EB movement out there)

- At the interchange with I-80 (thought thee were plans for flyovers at this interchange to fix the WB movement)

- At the northern interchange with I-55

- At the western interchange with I-465

- At the eastern interchange with I-465

- WB I-74 appears to go down to a single lane at the eastern intersection with I-275, looks like the second lane was removed to fix a forced merge:
http://maps.google.com/maps?hl=en&ie=UTF8&ll=39.214047,-84.680171&spn=0.003159,0.0103&t=k&z=18

[barcncpt44]

I-20 in Birmingham after the I-59 interchange the right lane exits; as you go down the ramp the right lane becomes a exit only lane.

[froggie]

Other former examples of the NON-RAMP variety:

- Parts of I-20 through Vicksburg, MS, between Bovina and Clinton, MS, and west of Meridian, MS were initially built as 2 lanes.  The segment west of Meridian was widened to 4 lanes ca. 1968, through Vicksburg ca. 1973 (coinciding with the Mississippi River bridge), and betwen Bovina and Clinton was slowly upgraded in stages through the '60s and early '70s.

- I-91 between Derby Center and Derby Line, VT was built as 2 lanes ca. 1962.  It was widened ca. 1970.

- I-15 north of Idaho Falls, ID into Montana was initially built as 2 lanes.

- Perusing my earlier Montana maps shows several segments of I-15, I-90, and I-94 that were initially built as 2 lanes.

[yakra]

To that end, I-95 was initially constructed as a Super-2 from the Canadian border in Houlton to... where, like Orono or Old Town or something? Upgraded in the early 80s IIRC.

[SidS1045]

-I-95 northbound when it meets the south end of I-93 and merges onto MA 128 in Canton, MA.

Only on the ramp to 128 north.  The ramp to (former) 128 south (I-93 & US-1 N) is two lanes.

[roadman65]

In Fort Lee, NJ the upper level connection to the I-95 local lanes drops down to a single lane at NJ 4. It then merges into the lower level lanes to the I-95 local lanes that have two lanes.

[vtk]

I-71 is routed through a single-lane ramp each way through the Mound-Sandusky (West Split) Interchange (Jct I-70 & OH-315) in Columbus.  I-70 Westbound is forced into a single lane just before joining I-71 Southbound in the East Split Interchange; there's another lane there but it's Exit Only for 4th Street.  Both of these situations are supposed to be rectified as the I-70/71 project takes its course, giving I-70 and I-71 three and two through lanes each way, respectively.  (Or so says the overall description -- for some reason, the actual plans show only two through lanes westbound on I-70 through both major interchanges...)

Also, I think NB I-71 narrows to a single lane just before merging with I-75 in northern Kentucky.  Now why couldn't they have let the two Interstates join, and then drop a lane a bit downstream?