Strange Interchanges

[ran4sh]

Believe that is what A - B - C suffixes are for.  Have no idea if that is standard.   

In a sequential numbering system, I would have used separate numbers. It's not a violation for exit numbers to be skipped in one direction if they exist in the other direction. At least that is how Georgia had handled it back when it was a sequential exit state.

[chrismarion100]

IDK if these count but here is a SPUI next to a bunch of ramps which I can't describe what they look like
https://www.google.com/maps/@44.7921525,-91.4533738,1482m/data=!3m1!1e3?hl=en
This is an interchange where one of the exits go off way to soon
https://www.google.com/maps/@44.7707878,-91.4244258,620m/data=!3m1!1e3?hl=en

[J N Winkler]

Was this segment of I-81 built fairly early in the era of first Interstate construction?  There is a similar succession of restricted-access interchanges a bit further north in Lacona.

The first sections of I-81 north of Syracuse opened in the late 1950's, but both the Pulaski and Lacona interchanges appear to be part of the section that opened in 1961, at least according to Wikipedia.

Thanks--I wondered, because FHWA has become more strict about there being no missing movements.  It seems these interchanges were planned and approved when things were much looser.

[vdeane]

There's also this odd exit.

Which, to bring things full circle, happens to be a pretty good candidate for this thread! 

I've never understood why that one ramp exists without any counterpart whatsoever. At least a southbound entrance ramp would be nice, and you could probably make the case for a full interchange, especially if there was better access to the development south of Mud Creek.

I would have thought vdeane would have recognized one of the largest wetland areas in the region...

Oddly enough, the one-ramper was just discussed at SMTC.  Never going to be a full interchange due to the gigantic wetland issue.

1. Don't blame me for webny99's interchange/access concept.
2. I was only looking for the sign, but at one point, one has to wonder why even that ramp was built.  Given that traffic can't get back on, it would seem that that ramp would have limited utility.

[webny99]

Yeah, it was me that brought the wetlands up. I was not aware of the issues there, presumably environmental. But it certainly makes sense that that's why there's no development or thru N/S roads in that area.

[Rothman]

Yeah, it was me that brought the wetlands up.

No, I did, in terms of the one-ramp exit off of 481.

I wasn't blaming vdeane, but she did call it an odd exit.  And it certainly is odd, and the wetlands are why, of which I was surprised she was unaware.

The ramp just provides access to the community for returning commuters from Syracuse. 

[jakeroot]

I'm sure they could fit a flyover with a tight merge if they really wanted.

I find it more odd that they build the off-ramp fully knowing they wouldn't build a parallel on-ramp. That's pretty unusual even if one ramp was much easier/less environmentally destructive than the other.

[Rothman]

I'm sure they could fit a flyover with a tight merge if they really wanted.

I find it more odd that they build the off-ramp fully knowing they wouldn't build a parallel on-ramp. That's pretty unusual even if one ramp was much easier/less environmentally destructive than the other.

Welcome to the East.

[jakeroot]

I'm sure they could fit a flyover with a tight merge if they really wanted.

I find it more odd that they build the off-ramp fully knowing they wouldn't build a parallel on-ramp. That's pretty unusual even if one ramp was much easier/less environmentally destructive than the other.

Welcome to the East.

Seattle says hello.

[Occidental Tourist]

I've always found this interchange off the 215 at CA-74 east near Hemet, California to be odd.

Case street is south of the train tracks and runs along them to the northwest.  Highway 74 is north of the train tracks and runs along them to the southeast.  Before the US 395 expressway bridge (later I-215) was built, Case Avenue met Highway 74 and US 395 in an at-grade, four-way intersection that was bisected diagonally by the train tracks.



When they built the expressway over the tracks and the offramp, they basically relegated Case Avenue as a non-essential route and focused the movements for the offramp to the Highway 74 movement.

[jay8g]

I'm sure they could fit a flyover with a tight merge if they really wanted.

I find it more odd that they build the off-ramp fully knowing they wouldn't build a parallel on-ramp. That's pretty unusual even if one ramp was much easier/less environmentally destructive than the other.

Welcome to the East.

Seattle says hello.

There was, at one point, a southbound off ramp to go along with that one, which connected up to S Trenton St here. It seems to have been removed when the second 1st Ave S bridge was built, and I'm not sure why as it seems like it would still be useful.

[empirestate]

I just dropped by to say, it feels like a missed opportunity that this thread wasn't titled as I've done here.

[MCRoads]

Oh Florida, what are you smoking?

[SEWIGuy]

Oh Florida, what are you smoking?

It looks like this is done so that traffic entering the highway queues up in the loop, and then can be run on the same light cycle as the exiting traffic turning left.  Instead of queueing on the bridge and waiting for an arrow.

[MCRoads]

Seems like if you are willing to use the extra ROW for this, maybe a roundabout interchange could work better here.

[DJStephens]

Looks like a DDI, but it isn't. Strange.   What would be the main reason not to use either a DDI or a SPUI here?   

[froggie]

SPUI would require rebuilding the bridges on 95 over 16 so that one's probably out.  I do have to ask why a DDI wasn't considered...I don't see what advantage this looped left turn would give over a DDI.

[CoreySamson]

To me, it looks (and probably functions) like a combination of a CFI, a normal diamond interchange, and a SPUI. I like it.

As for my own contribution to this thread, here is this bizarre Texanized CFI in San Marcos, TX:
https://www.google.com/maps/@29.8826011,-97.9212863,407m/data=!3m1!1e3

[jakeroot]

If the idea is to allow traffic coming off the freeway and traffic entering the freeway to enter at the same time, the capacity for the on-ramp would seem to only be as high as the number of cars that could be stored in the loop section beyond the signal, something that seems to be of very low capacity, even for the loop with the double lane section. Further, the interchange is still limited in capacity by the overlapping off-ramp movements; even allowing simultaneous on and off ramp movements would not eliminate this other issue (something that would be solved with a DDI).

I would assume a DDI is not being used here because of the high levels of through traffic? It's not quite clear to me why they need extra capacity at this location. If there is an issue with left turn cycle length, I would think double left turns at the ramp terminals would be a more than sufficient improvement.

[formulanone]

I just dropped by to say, it feels like a missed opportunity that this thread wasn't titled as I've done here.

Interstranges

[empirestate]

I just dropped by to say, it feels like a missed opportunity that this thread wasn't titled as I've done here.

Interstranges

Yes, that one...but did you un-edit my subject line so as to take the credit for yourself?

[Tom958]

A hybrid directional and trumpet three-way interchange in Derby, England.

[tolbs17]

I have to say this interchange is weird because of the ramp entering North I-95 is smaller compared to the other ramps. And the reason that could be is because it used to have a very short merging distance because the Little River bridge was only 2 lanes when it was built. But it later got fixed. And I'm sure this interchange will be redesigned when it gets rebuilt.

[roadman65]

https://goo.gl/maps/DAip4RBXsBox5NpW9
Rather than start a new topic, but to add to the list, above is one that is strange, but very safe as the curb prevents weaving from US 9W traffic in the right on ramp lane from aggressively entering the I-95 express road.

So strange in setup, but practical in use.

[pderocco]

Here's an interchange I've been through hundreds of times, but I could never draw it for you. I couldn't draw it two seconds after carefully examining the map. It's the connection between I-95 and US-1 in Lynnfield, MA.

https://goo.gl/maps/9LgVmbJs5gXMK2K29