Best Interchange Designs

[kphoger]

I like this cloverleaf in NOLA for it's lack of weaving on the arterial:
https://www.google.com/maps/@29.9974594,-90.1542972,869m/data=!3m1!1e3

Now, that looks downright beautiful.

[ztonyg]

One of the ugliest stacks has to be I-37/I-410.

That's hideous. That's significantly uglier than my vote: I-75/I-696

Might have a stack that's uglier: the Ghost Stack on I-84 near Hartford. They did not give 2 craps about aesthetics while designing this...

I actually considered this one but I thought this actually has some aesthetic appeal with the ramps just appearing out of the foliage another contender may be I-70 / I-695 near Baltimore. At least the ghost stack is partially used (as a semi-directional T).

[kphoger]

For system interchanges, I like a good three-way stack where both bridges cross at a single point, such as I-57/I-64 in Illinois.

For four-way system interchanges, it all depends on the particular situation.  But I generally favor a cloverleaf with two of the loops replaced with flyovers, like what they've done with US-54/I-235 here in Wichita.

For regular interchanges, I like the roundabout-under-highway design, such as in Newton, KS.

[ran4sh]

The Parclo B4 for freeway-nonfreeway interchanges (the B4 is the type which separates freeway exit traffic by direction but the entering traffic shares a ramp, requiring left turns from the non-freeway road)

The stack or turbine for freeway-freeway interchanges. Cloverstacks are ok in some situations because there is no weaving, but it should be designed so that the high-traffic left-turn movement uses one of the flyover ramps.

The echelon for a nonfreeway-nonfreeway interchange. It would be nice to see more interchanges for busy intersections where neither road warrants a freeway upgrade.

[Bickendan]

This might be going out on a limb, but I like both Ross Island Maze and the Fremont Stack in Portland.

[1995hoo]

Since some of you are discussing ugly stacks, I dislike the junction of the M4 and the M25 Orbital near Heathrow because it looks off-balance due to the way the M25 is off-center. I suspect the railroad tracks running through there might have something to do with why it's designed that way.

[davewiecking]

I have always liked I-395 and King Street in Alexandria, Virginia, because of how it nicely and cleanly eliminates the weave-area problem that is a central issue with a standard cloverleaf. Yes, it requires two additional overpasses, but overall those are a minor addition when compared to flyover ramps or similar.
(snip)

Very similar design is used where MD-43 intersects I-95 north of Baltimore, except the "loop ramps" also allow for left hand turns to facilitate left turns at cross streets near the intersection.

[webny99]

I have always liked I-395 and King Street in Alexandria, Virginia, because of how it nicely and cleanly eliminates the weave-area problem that is a central issue with a standard cloverleaf. Yes, it requires two additional overpasses, but overall those are a minor addition when compared to flyover ramps or similar.
(snip)

Very similar design is used where MD-43 intersects I-95 north of Baltimore, except the "loop ramps" also allow for left hand turns to facilitate left turns at cross streets near the intersection.

Whoa. The left turn from the loop is a really interesting concept. For those who are curious, start here.

[JoePCool14]

I also like the I-(1)96/US 131 intersection in Grand Rapids:
https://www.google.com/maps/@42.973197,-85.6785569,1019m/data=!3m1!1e3

I'm gonna have to disagree with you on that one. That interchange is functionally pretty bad considering we're talking about two freeways intersecting with ramps that can only be taken at 30 MPH.

[jmacswimmer]

Since some of you are discussing ugly stacks, I dislike the junction of the M4 and the M25 Orbital near Heathrow because it looks off-balance due to the way the M25 is off-center. I suspect the railroad tracks running through there might have something to do with why it's designed that way.

I've looked at that interchange in satellite view several times before, and somehow never noticed the rail line running directly thru the interchange until you pointed it out 

My thought on M25's alignment (without the rail perspective, as noted above) is that it's simply to keep the alignment on one gradual and thus shallower horizontal curve thru the interchange, as opposed to a shorter but sharper curve on each side to align perfectly thru the center of the interchange?

The M23/M25 interchange down towards Gatwick is much more centered (and looks similar in terms of the structures).

[CoreySamson]

I also like the I-(1)96/US 131 intersection in Grand Rapids:
https://www.google.com/maps/@42.973197,-85.6785569,1019m/data=!3m1!1e3

I'm gonna have to disagree with you on that one. That interchange is functionally pretty bad considering we're talking about two freeways intersecting with ramps that can only be taken at 30 MPH.

That's interesting. I only liked it because of its tight footprint, but if it's not efficient, then maybe it isn't that great.

[sprjus4]

Tight ramps, left exits & entrances.

From a right of way standpoint, has a small footprint, good in that regard. Functionability? Seems to be poor.

[Tom958]

For compactness, it's hard to beat this one, even with the railroad throwing in an extra level. And this one, with its compact central structure.

[SkyPesos]

Since some of you are discussing ugly stacks, I dislike the junction of the M4 and the M25 Orbital near Heathrow because it looks off-balance due to the way the M25 is off-center. I suspect the railroad tracks running through there might have something to do with why it's designed that way.

Not really an ugly stack, but here's an off-centered stack in my state, at I-75 and US 35.

[kphoger]

I think those off-center stacks look just as elegant as a centered one–especially the M4/M25 one.

[tradephoric]

I've always been confused why agencies gravitate towards Parclo A4s.  As an example Ontario and Caltrans has designed a massive number of Parclo A4 interchanges and hardly any Parclo B4s.  And when a full blown cloverleaf is converted to a partial cloverleaf, a Parclo A4 design is usually chosen over a Parclo B4 even though both designs would require the same ROW.  Like this example in Augusta, Georgia.  Either type of Parclo could have been selected but they designed a Parclo A4:


https://www.google.com/maps?ll=33.45041,-82.07465&z=17&t=h

[OCGuy81]

I really like the way they redesigned the Mitchell Interchange in Milwaukee.

[dlsterner]

I have always liked I-395 and King Street in Alexandria, Virginia, because of how it nicely and cleanly eliminates the weave-area problem that is a central issue with a standard cloverleaf. Yes, it requires two additional overpasses, but overall those are a minor addition when compared to flyover ramps or similar.
(snip)

Very similar design is used where MD-43 intersects I-95 north of Baltimore, except the "loop ramps" also allow for left hand turns to facilitate left turns at cross streets near the intersection.

Whoa. The left turn from the loop is a really interesting concept. For those who are curious, start here.

That loop ramp is pretty new.  It's a big help when traveling southbound on I-95 and trying to get to White Marsh Mall (via MD 43 and Honeygo Blvd).  Prior to that there was a lot of weaving with people coming down the other ramp to MD 43 and trying to quickly slide several lanes left in order to get to the left turn at Honeygo.  Was glad to see it available once it opened.

[kurumi]

For some reason I pictured "A4" and "B4" as "after" and "before", but it's the opposite: "ahead" and "behind".

[tolbs17]

Tight ramps, left exits & entrances.

From a right of way standpoint, has a small footprint, good in that regard. Functionability? Seems to be poor.

I-40 I-440 one is proposed there.

[ran4sh]

I've always been confused why agencies gravitate towards Parclo A4s.  As an example Ontario and Caltrans has designed a massive number of Parclo A4 interchanges and hardly any Parclo B4s.  And when a full blown cloverleaf is converted to a partial cloverleaf, a Parclo A4 design is usually chosen over a Parclo B4 even though both designs would require the same ROW.  Like this example in Augusta, Georgia.  Either type of Parclo could have been selected but they designed a Parclo A4:


https://www.google.com/maps?ll=33.45041,-82.07465&z=17&t=h

In the case of Augusta, one possibility is because drivers are already familiar with the parclo A4 at I-20 & SR 28 (Washington Rd).

But in general it seems that the benefits of A4 are more obvious than the benefits of B4 (A4 doesn't require left-turn lanes on the cross road, but B4 traffic signals can be timed to fit any progression plan because the signals don't stop both directions of the cross road).

[sparker]

One of the ugliest stacks has to be I-37/I-410.

Definitely a yecch!.  That's the fugliest set of bridge bents I've ever seen; looks like the design was done by a grade-school kid using concrete versions of Lincoln Logs!  That's one interchange I'm glad I've never seen in person!

[Scott5114]

One of the ugliest stacks has to be I-37/I-410.

Definitely a yecch!.  That's the fugliest set of bridge bents I've ever seen; looks like the design was done by a grade-school kid using concrete versions of Lincoln Logs!  That's one interchange I'm glad I've never seen in person!

I saw it in person but have no memory of it; probably because I'd driven down from Oklahoma the same day and by the time I went through that one I had seen so many stack interchanges in Texas they stopped registering as anything interesting.

[jakeroot]

I don't think I have one specific kind of freeway interchange that I prefer. In general, I just like the one that best utilizes the available land. Or in other terms, the one that is the most efficient in a given space.

Couple great examples of high-capacity but compact freeway-to-freeway interchanges that I find very neat. They involve loops, so both could technically be categorized as cloverstacks:
* 5 Fwy @ 55 Fwy, Santa Ana
* CA-92 @ 880 Fwy, Hayward

In terms of regular freeway-to-service road interchanges, I prefer partial cloverleafs. Ideally, B4 configuration to limit the need to place any signals:
* Bradford Dr @ Al-255, Huntsville (+1000 for a unsignalized double left)
* I-64 @ Kingshighway in East St Louis (A4 Parclo with left-side merge)

[Angelo71]

I like VA-267 and I-495 in Tysons.
I also like I-79 at I-80, and I-79 at US-322/US-19 at Meadville.