Favorite Interchange Type?

[Jmiles32]

The one and only Springfield Interchange(Mixing Bowl) at the intersection of I-95, I-395, and Capital Beltway. Truly an engineering masterpiece.

[triplemultiplex]

Here is a theoretical interchange design known as the folded interchange.  It's basically a Parclo B4 but with "diverging" on-ramps.  The benefit is left-turning traffic entering onto the freeway only has to travel through one traffic light as opposed to two.  The downside is you need a lot of ROW along the arterial to fit the "diverging" on-ramps, but some places already have extremely wide medians (ie. Detroit).  This interchange wouldn't be practical everywhere though:

Reminiscent of WisDOT's plan for the Stadium Interchange (I-94 & WI 175/Miller Park Way):

Instead of loops, though, it has low-speed flyovers.


I like diamond interchanges between two roads that are both two lanes.
I like parclo interchanges between roads meeting at sharp angles with the loop ramps in the "acute" quadrants.
I like interchanges that are like half-built at the end of a freeway because of the potential promise of extending them in the future.  Even if the continuation has been cancelled, it's still neat.  Because it shows foresight.  Just in case we want to keep going, we'll leave it like this so we can pick it up again right here.

[freebrickproductions]

Whatever this monstrosity is (Parclo+SPUI?):
https://www.google.com/maps/@34.7352393,-86.5924751,1575m/data=!3m1!1e3?hl=en
I also like the infamous "Malfunction Junction" in Birmingham as well, along with the nearby one for I-20/I-59 and US 31/US 280:
https://www.google.com/maps/@33.5245025,-86.8154717,2237m/data=!3m1!1e3?hl=en

I guess I'm just a fan of odd interchanges.

[Plutonic Panda]

I am blown away by this interchange in Huntsville, AL!!!



w.t.f. super rad though.

[sparker]

Now THAT's a nice design -- considering the terrain, the development of the area, and the angles at which the roadways intersect.  And no left exits from the main carriageways -- the engineers deserve congratulations! 

[jakeroot]

I think it's hideous. It's so visually obtrusive. It's too bad they couldn't find a way to make the design smaller. I award them zero points.

[J N Winkler]

Whatever the hell the Grandview Triangle would be classified as. I'm not so much a fan of an interchange type, as I am a fan of more unique interchanges.

The Grandview Triangle is an interchange complex with a wye interchange handling the I-49 to I-470 connections and a directional interchange handling the I-435 to I-49 movements.

The big reconstruction and expansion circa 2002 actually did little to change the sense of the various movements.  However, it greatly improved operations by removing the overtight folded-diamond parclo at Red Bridge Road in favor of a regular diamond and altering the sense of the collector-distributor roads on either side of the I-49 roadway between the I-435 directional and the I-470 wye.

[johndoe]

The Huntsville example is cool; I imagine some drivers are frustrated they can't go from one Interchange to the next.

[hm insulators]

Whatever the hell the Grandview Triangle would be classified as. I'm not so much a fan of an interchange type, as I am a fan of more unique interchanges.

I think I'm the same way. I always liked the elaborate freeway interchanges in Los Angeles. Even as a little kid, if we were driving down a freeway I'd never been on and I saw on the guide sign another freeway coming up, I couldn't wait until we got to the interchange to see what it looked like. I even remember being vaguely disappointed at the interchanges of US 101 and I-405 and US 101, California 170 and CA 134 the first time I saw them. I thought they were boring (and still do, from a structural standpoint--they're compact little things) compared to, say I-10 with I-405 or the East L.A. interchange with their soaring transitions and wild designs. And of course, the Four Level is the iconic interchange in L.A.

The freeway interchanges in Phoenix are stacks with simple designs compared to some of the wilder ones in L.A., but I still like them.

[coatimundi]

I am blown away by this interchange in Huntsville, AL!!!

I saw this posted as a "monstrosity" and thought "That's actually pretty nice." I think what's bad about it is that the SPUI on the east side has ramps that are all inside and under the other ramp viaduct. That would likely cause visibility problems, but there's not much else you can do if you have to have a SPUI. I don't know how the traffic is there, but it may require a SPUI. Personally, I prefer it, in central business districts, when there are a couple of access points at the edges of the area and no local interchanges in between, allowing traffic to more easily merge and navigate the freeway interchange.
I've only been to Huntsville once, but I found the freeway system (and road system, really) to be pretty nice. It seems like a lot of money goes to transportation projects there and, looking at a map of what seems like a very extensive freeway system for a city of under 200,000, it appears to confirm that.

[jwolfer]

I like turbine interchanges, such as I-4 and I-75 near Tampa and I-295 and Butler Blvd in Jacksonville.  Very symmetric and no weaving.  Granted the left turn movements are long, but that's part of the appeal to me for some reason.

Me too...

[Rothman]

What Scheme Z evolved into.

[freebrickproductions]

I am blown away by this interchange in Huntsville, AL!!!

I saw this posted as a "monstrosity" and thought "That's actually pretty nice." I think what's bad about it is that the SPUI on the east side has ramps that are all inside and under the other ramp viaduct. That would likely cause visibility problems, but there's not much else you can do if you have to have a SPUI. I don't know how the traffic is there, but it may require a SPUI. Personally, I prefer it, in central business districts, when there are a couple of access points at the edges of the area and no local interchanges in between, allowing traffic to more easily merge and navigate the freeway interchange.
I've only been to Huntsville once, but I found the freeway system (and road system, really) to be pretty nice. It seems like a lot of money goes to transportation projects there and, looking at a map of what seems like a very extensive freeway system for a city of under 200,000, it appears to confirm that.

I called it a "monstrosity" because it's probably the largest interchange in the area, and the fact that it's two interchanges in one. Huntsville is actually Alabama's largest city that's growing the fastest, so the extensive freeways will be very useful in the future. We're actually expected to be the largest city in 2025, surpassing Birmingham in 2022, as per predictions in November.

[Buffaboy]

I am a fan of unique interchanges. Near me, this is the only one I can think of:

https://www.google.com/maps/@42.8780819,-78.8719363,19z/data=!3m1!1e3

Other than that, good old fashion diamonds.

[jeffe]

I've never quite understood why California was so keen on parclos, even in far-flung suburban areas, like on 99 south of Bakersfield and 101 in Gilroy. But they always seem to have the loop for the entrance ramp instead of the exit, requiring a traffic signal still.

I believe California likes the A4 (loop on-ramp) parclos because it eliminates all of the left hand turns.  In a diamond or a B4 (loop off-ramp) parclo, double or even triple left turn lanes may be needed to handle the left turning traffic entering the freeway.

One issue with the B4 (loop off-ramp) parclo is it has freeway speed traffic entering the loop ramp.  As you noted, these are rare in California, but the few that do exist have considerable damage to the outside barrier on the loop ramp.

[ET21]

DDI, but I loved the designs of some turbines.

My personal favorite interchange is I-88/I-355/US-34 in Illinois
https://www.google.com/maps/@41.8156926,-88.0368935,15z

[SignGeek101]

Am I the only one who really likes Diamonds? They're simple and work beautifully. I can't say they're my favourite though (I do like DDI's though). 

TBH, I don't really know if I have a favourite. I guess my favourite is the design that optimizes cost and traffic flow at the same time.

I've never quite understood why California was so keen on parclos, even in far-flung suburban areas, like on 99 south of Bakersfield and 101 in Gilroy. But they always seem to have the loop for the entrance ramp instead of the exit, requiring a traffic signal still.

Cough cough... Ontario ...cough cough

Even in rural areas (where I think diamonds should be used), A4's are used. There's a rumour Ontario invented the Parclo A4, I'm not sure if that's true but they are everywhere there.

[20160805]

Is it practical to have interchanges between two surface-level arterials? The reason I ask is I have been playing around with diamonds and 2-level stack interchanges between arterials and I want traffic on arterials to flow smoothly at 40-45  mph.

The disadvantage I could see would be space and cost, but I'd like someone who knows more than I do to give me more information about this concept.

[hotdogPi]

Is it practical to have interchanges between two surface-level arterials? The reason I ask is I have been playing around with diamonds and 2-level stack interchanges between arterials and I want traffic on arterials to flow smoothly at 40-45  mph.

The disadvantage I could see would be space and cost, but I'd like someone who knows more than I do to give me more information about this concept.

Example: MA 28 and MA 125. (To find it on a map, draw a line from Boston due north to the New Hampshire border. The interchange should be slightly west of the midpoint of that line, but still east of I-93.)

[epzik8]

I love simple diamonds and anything with collector-distributors.

[7/8]

Is it practical to have interchanges between two surface-level arterials? The reason I ask is I have been playing around with diamonds and 2-level stack interchanges between arterials and I want traffic on arterials to flow smoothly at 40-45  mph.

The disadvantage I could see would be space and cost, but I'd like someone who knows more than I do to give me more information about this concept.

I know there's one in Kitchener, ON at Huron Rd and Homer Watson Blvd. I always thought it was kind of cool. I can see it being useful at particularly busy arterial-arterial intersections. But then the question arises: if you need an interchange, is a conversion to a freeway warranted?

https://www.google.ca/maps/@43.3991979,-80.4533735,17.2z

[jeffandnicole]

Is it practical to have interchanges between two surface-level arterials? The reason I ask is I have been playing around with diamonds and 2-level stack interchanges between arterials and I want traffic on arterials to flow smoothly at 40-45  mph.

The disadvantage I could see would be space and cost, but I'd like someone who knows more than I do to give me more information about this concept.

While "Common" may be exaggerating it, there are plenty around. 

A few from NJ:

Routes 38, 41 and 73: https://goo.gl/maps/H3XRT8viNsC2

A newer one at Routes 70 & 73: https://goo.gl/maps/QqRv1deR1Kz

An example from PA; Routes 322 & 452: https://goo.gl/maps/fPHJE55xQtT2

[CtrlAltDel]

Is it practical to have interchanges between two surface-level arterials? The reason I ask is I have been playing around with diamonds and 2-level stack interchanges between arterials and I want traffic on arterials to flow smoothly at 40-45  mph.

The disadvantage I could see would be space and cost, but I'd like someone who knows more than I do to give me more information about this concept.

Here's one.
https://www.google.com/maps/@41.907423,-87.8834958,314m/data=!3m1!1e3

[20160805]

Thank you everyone 

NJ 38 and 73 look like nice roads  - how's the traffic?  73 looks for the most part just like the kind of street I wanted - just remove those last few traffic lights and move the driveways to a service road and it would be an A+ road for me.

There's an interchange between County CE (College Ave) and County N just east of Appleton, WI, but I'm not sure that counts because CE is more like an expressway over there.

Is it practical to have interchanges between two surface-level arterials? The reason I ask is I have been playing around with diamonds and 2-level stack interchanges between arterials and I want traffic on arterials to flow smoothly at 40-45  mph.

The disadvantage I could see would be space and cost, but I'd like someone who knows more than I do to give me more information about this concept.

I know there's one in Kitchener, ON at Huron Rd and Homer Watson Blvd. I always thought it was kind of cool. I can see it being useful at particularly busy arterial-arterial intersections. But then the question arises: if you need an interchange, is a conversion to a freeway warranted?

https://www.google.ca/maps/@43.3991979,-80.4533735,17.2z

I wouldn't think freeway conversion is needed - then you could have 5-10 freeways in a mid-sized city of 120,000.  It can be kind of like an expressway, still having at-grade intersections with minor roads.

[cappicard]

Thank you everyone 

NJ 38 and 73 look like nice roads  - how's the traffic?  73 looks for the most part just like the kind of street I wanted - just remove those last few traffic lights and move the driveways to a service road and it would be an A+ road for me.

There's an interchange between County CE (College Ave) and County N just east of Appleton, WI, but I'm not sure that counts because CE is more like an expressway over there.

Is it practical to have interchanges between two surface-level arterials? The reason I ask is I have been playing around with diamonds and 2-level stack interchanges between arterials and I want traffic on arterials to flow smoothly at 40-45  mph.

The disadvantage I could see would be space and cost, but I'd like someone who knows more than I do to give me more information about this concept.

I know there's one in Kitchener, ON at Huron Rd and Homer Watson Blvd. I always thought it was kind of cool. I can see it being useful at particularly busy arterial-arterial intersections. But then the question arises: if you need an interchange, is a conversion to a freeway warranted?

https://www.google.ca/maps/@43.3991979,-80.4533735,17.2z

I wouldn't think freeway conversion is needed - then you could have 5-10 freeways in a mid-sized city of 120,000.  It can be kind of like an expressway, still having at-grade intersections with minor roads.

Manhattan, Kansas has several along Seth Childs Road (K-113) with Anderson Avenue and with Kimball Avenue.


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