Strange Interchanges

[mightyace]

My hometown interchange, US 11 and I-80.

Left exits and entrances galore, extensive weaving and and to get from US 11 North to I-80 west, a short, tight U-turn ramp followed by crossing two lanes of US 11 S!

I don't see why this isn't just a folded diamond.

I don't know either.  I-80 goes uphill west of the interchange but the Milesburg exit (#158) has similar constraints.  Railroad tracks on the east side of the interchange and the hill is much longer and steeper than that at exit 241.

The only thing I can think of is that this design keeps traffic free flowing on both US 11 and most of the ramps to/from I-80.

Milesburg:
http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=Milesburg,+PA&aq=0&sll=37.0625,-95.677068&sspn=31.977057,79.013672&ie=UTF8&hq=&hnear=Milesburg,+Centre,+Pennsylvania&ll=40.956162,-77.770243&spn=0.007438,0.01929&t=h&z=16

[pianocello]

I-90/94 in Downtown Chicago comes to mind...

[Brandon]

I-90/94 in Downtown Chicago comes to mind...

Which I-90/94 interchange?  The Edens Junction or the Skyway Junction?  Granted the Circle Interchange can be a bit strange, but that's at I-90/94 (Ryan and Kennedy Expys) and I-290 (Ike Expy and Congress Pkwy).

[Henry]

The junction of I-85 & I-77/US 21 in Charlotte NC, the carriageways of I-77 cross over before and after the I-85 interchange.

I-95 and I-695 north of Baltimore used to do that when they met, but now it's a conventional stack interchange.

I-90/94 in Downtown Chicago comes to mind...

Which I-90/94 interchange?  The Edens Junction or the Skyway Junction?  Granted the Circle Interchange can be a bit strange, but that's at I-90/94 (Ryan and Kennedy Expys) and I-290 (Ike Expy and Congress Pkwy).

He said Downtown Chicago, so he can't mean the Edens or the Skyway, because one interchange lies to the north of there, and the other to the south. And I believe you answered his question with the circle interchange thing.

[froggie]

I-95 and I-695 north of Baltimore used to do that when they met, but now it's a conventional stack interchange.

Not completely true.  The I-695 carriageways still cross each other through the interchange.

[ftballfan]

I-95 and I-695 north of Baltimore used to do that when they met, but now it's a conventional stack interchange.

Not completely true.  The I-695 carriageways still cross each other through the interchange.

US-131 does the same thing at I-196. Also, the carriageways for I-196 are at different levels, one going over US-131 and the other going under.

[pianocello]

Actually, I was referring to the string of interchanges between the circle and Ohio Street, but the Circle interchange is also pretty strange.

[roadman65]

How about the O Hare Interchange between I-90, I-190, and I-294.   There is no exit to EB I-190 from NB I-294 spite that there is a WB to SB ramp there.  Instead there is a direct interchange to I-90 EB where I-190 goes anyhow.  There is no WB I-90 to SB I-294 and therefore uses I-190 to make the connection!

I am guessing it all has to do with the tolling as all exits from both toll roads to the airport here need them cause the mainline plazas are only halfees and are split to either side of J-90 and I-190 on 294 and one heading west on I-90.  Of course the Illinois Tollway Authority is not going to let you pass by without paying toll.

[Brandon]

How about the O Hare Interchange between I-90, I-190, and I-294.   There is no exit to EB I-190 from NB I-294 spite that there is a WB to SB ramp there.  Instead there is a direct interchange to I-90 EB where I-190 goes anyhow.  There is no WB I-90 to SB I-294 and therefore uses I-190 to make the connection!

I am guessing it all has to do with the tolling as all exits from both toll roads to the airport here need them cause the mainline plazas are only halfees and are split to either side of J-90 and I-190 on 294 and one heading west on I-90.  Of course the Illinois Tollway Authority is not going to let you pass by without paying toll.

Not at all.  There's just no point to a ramp there except for River Rd.  The only exit is for River Rd, and that can accessed via different ramps.  The deficiency in this regard exists for both SB I-294 and EB I-90, and it's worse for EB I-90.

[Brandon]

Actually, I was referring to the string of interchanges between the circle and Ohio Street, but the Circle interchange is also pretty strange.

The Rapid-Fire Ramps on the Kennedy Expy.  One block apart each and right exit, left entry.  Lots of fun to merge from. 

[Henry]

Actually, I was referring to the string of interchanges between the circle and Ohio Street, but the Circle interchange is also pretty strange.

The Rapid-Fire Ramps on the Kennedy Expy.  One block apart each and right exit, left entry.  Lots of fun to merge from. 

Totally forgot about that one! At least it's not as bad as this mess of ramps on I-277 in Charlotte:


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And try navigating through this inverted cloverleaf at I-77:


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If you're arriving on the I-77 C/D roads, MERGE IMMEDIATELY! Or you'll find yourself continuing onto the road you just exited from.

[golden eagle]

^^

That Charlotte interchange looks more like the Spaghetti Junction on I-85 near the ATL. Perhaps more so.

[Alps]

I-95 and I-695 north of Baltimore used to do that when they met, but now it's a conventional stack interchange.

Not completely true.  The I-695 carriageways still cross each other through the interchange.

Is that not going to get fixed?

[froggie]

 Just as with the express lane ramps, it got deferred due to cost and MdTA's recent funding issues.

[J N Winkler]

Actually, a fix will be underway soon.  MdTA has just advertised a radically descoped version of the original Phase II contract:

http://www.mdta.maryland.gov/Contracts/Construction/contracts/KH/KH1302.html

Construction is still going forward according to the original plan but a considerable amount of the work is being deferred to the future (e.g., one major flyover bridge will have only three piers built under this contract, with the other piers and superstructure coming later).

[froggie]

As I understand it, that project is to construct the ETLs through the 95/695 interchange, and will not involve the I-695 mainline lanes.

[Mergingtraffic]

CT-8 SB in Waterbury, CT has a right and left on-ramp, both with no merge time at the same spot!

The right on-ramp comes from I-84 and the left is from a  side street.  Who designed this!?!?! The worse part this opened in 1969, so design standards were improved by then.

http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=waterbury,+ct&aq=&sll=37.0625,-95.677068&sspn=37.052328,67.412109&ie=UTF8&hq=&hnear=Waterbury,+New+Haven,+Connecticut&ll=41.550379,-73.050043&spn=0.00107,0.003079&t=h&z=19

WTF!
Good news, this whole interchange is slated to become a 4-level stack.  Of course, no funding.

[J N Winkler]

As I understand it, that project is to construct the ETLs through the 95/695 interchange, and will not involve the I-695 mainline lanes.

Yup, it won't finish off this interchange--I estimate that the plans set for the contract just advertised has about one-third to one-half the sheet count of the full Phase II plans set.  My impression, on a cursory review of the sign layouts and roadway plan sheets, is that MdTA is trying to deliver a down payment on I-95 congestion relief and get the ETLs up and running so they can start making money.  I don't know when the remainder of the work will get done, but at least this contract is a start, which is more than I expected a few months ago when all the indications were that Phase II had been shelved indefinitely.

[Henry]

Meet the Baltimore Spiral, which is not too far from the two tunnels:



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[SSOWorld]

Isn't any interchange on a closed-system toll road (ticket based) a strange one?  Trumpet interchanges to a single side of the road (or a cloverleaf/trumpet/stack in the case of freeways) to accommodate getting ticket/paying toll/scanning transponder combo?

Madison Beltline at Verona Road (where US 18/151 split from US 12/14) - not so much as "strange" as it is a diamond connecting a surface road to a freeway, but the traffic on Verona Road south is much deserving of a freeway (a study is being conducted on a plan to put a SPUI in first to connect the the two routes, then route 18/151 using a depressed direct connection to the beltline to the east where the SPUI would serve Verona Road's local traffic that essentially becomes a pair of frontage roads paralleling the freeway in the middle.  The frontage roads eventually merge with the freeway further south - taking all the cross streets off the highway.  Access between 18/151 from 12/14 to the west would go through the SPUI.

http://www.dot.wisconsin.gov/projects/d1/verona/docs/map-altstage3.pdf <-- this PDF shows the planned

[ftballfan]

How can I begin to explain this mess of ramps near Newark Liberty Airport?:
http://maps.google.com/maps?hl=en&ie=UTF8&ll=40.709206,-74.168401&spn=0.01324,0.056133&t=k&z=15

[berberry]

Seems like every big city has an interchange or two that defy description, a point people often make emphatically with failed attempts to describe them.  But just in terms of pure strangeness, I dunno.  It's an interesting question.

The first interchange that came to mind was the one in Louisville, KY near the river.  It's old and has lots of left exits and weaving issues.  I haven't been on it in many years, but I remember it fairly well because a couple decades ago I got caught in a lengthy traffic jam at that interchange, and while I waited I looked around trying to take it all in.  I couldn't.

Looking at it on this map fits with my memory, but that isn't saying much because like I said, I couldn't figure out how the junction worked even as I had time to sit and study it.  So I suppose their might have been some upgrading done in the time since I was there, but it doesn't look like it's been entirely rebuilt:

http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=louisville,+ky&aq=&sll=37.0625,-95.677068&sspn=25.288195,47.900391&ie=UTF8&hq=&hnear=Louisville,+Jefferson,+Kentucky&ll=38.259177,-85.741167&spn=0.012199,0.023389&z=15

For a small-town example, I offer the Vicksburg Twins, as I call them.  Two back-to-back half-cloverleafs with left-exiting "flyover" ramps.  Although weaving can become an issue on the non-freeway at each junction (it's rare), there are no cross-traffic left turns at any point, but there are movements you can't make.  If you should need to, you'd use the opposite interchange:

http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=vicksburg,+ms&aq=&sll=38.259143,-85.739815&sspn=0.006099,0.011694&ie=UTF8&hq=&hnear=Vicksburg,+Warren,+Mississippi&ll=32.345887,-90.838394&spn=0.02625,0.046778&z=14

[roadman65]

How about the single ramp interchange from I-95 NB to US 301 NB in EMporia, VA.  True that was left behind when I-95 used to end there back in the early 80's as it was a wye interchange with an entrance to I-95 SB from US 301 SB.  Actually US 301 SB exited itself to the left and both lanes of I-95 NB went under the current underpass on the ramp that is probably why VDOT left the ramp behind. 

[roadman65]

The I-405 and Sunset Boulevard Interchange in LA.  It has Sepulveda Boulevard pass through it, with no connection to either except for a ramp from WB Sunset to Sepulveda.

[UptownRoadGeek]

http://maps.google.com/?ie=UTF8&ll=29.968589,-90.108812&spn=0.004164,0.014613&t=k&z=17