Smallest DDIs and SPUIs

[MCRoads]

I have noticed that because DDIs and SPUIs often replace larger interchanges, they tend to be pretty large, and I was wondering if there are any compacted versions of these interchanges.

[Revive 755]

Couple nominations for smallest SPUI:

* IL 137/Amstutz Expressway at Grand Avenue/Mathon Drive in Waukegan
* IL 56 at Highland Avenue in Downers Grove

[ilpt4u]

Couple nominations for smallest SPUI:

* IL 137/Amstutz Expressway at Grand Avenue/Mathon Drive in Waukegan
* IL 56 at Highland Avenue in Downers Grove

I'll second the Highland Ave @ IL 56/Butterfield Rd SPUI. It is pretty tight

[MCRoads]

Think I might have found the smallest DDI... this thing is comical.

https://goo.gl/maps/YGAmpHEEogTvDSVD7

[US 89]

The tightest SPUIs I know of are the ones on Bangerter Highway (Utah 154) in the western Salt Lake Valley. Here's one example, at the 7800 South interchange.

[johndoe]

Think I might have found the smallest DDI... this thing is comical.

https://goo.gl/maps/YGAmpHEEogTvDSVD7

Wow that thing is strange!  I feel like maybe that one has been shown on here before but the more I look the weirder it is:
-weird bridge shape (and huge square footage with the frontage roads under)
-interesting frontage road to south (more bridge $)
-lack of eastbound off-ramp left turn (I guess you're supposed to use that south frontage road to turn around?) try some combos on Google maps directions for a laugh
(surprising DDI was most logical layout if you don't even have one of the four left-turn movements)
-more lanes on bridge in each direction than the upstream signals.  This is one of my biggest pet peeves on DDI - both ramp terminals have 2 lanes vs 2 lanes...so what good is that third lane doing you on the bridge?

I guess you could define "smallest" as number or lanes or tightness of geometry.  There's a DDI in NC that has really tight curves, I'd be impressed if any were tighter: https://goo.gl/maps/K1wUKEnPDkeKW1jj9

[MCRoads]

I would be interested to see if a single-lane DDI would offer any advantages over a regular diamond interchange. Are there any? I found out about a single lane SPUI in Garden City KS that may count towards the smallest SPUI in both space and lanes.

[johndoe]

There is a 2 lane DDI in Wyoming: https://maps.app.goo.gl/6Hhn2aU7VGvHVGRu7

[kphoger]

There is a 2 lane DDI in Wyoming: https://maps.app.goo.gl/6Hhn2aU7VGvHVGRu7

It's so small, I can't even see it!

[kphoger]

I would be interested to see if a single-lane DDI would offer any advantages over a regular diamond interchange. Are there any? I found out about a single lane SPUI in Garden City KS that may count towards the smallest SPUI in both space and lanes.

The DDI at US-65/MO-248 in Branson is one lane westbound but two lanes eastbound.

[hotdogPi]

There is a 2 lane DDI in Wyoming: https://maps.app.goo.gl/6Hhn2aU7VGvHVGRu7

It's so small, I can't even see it!

It's about a mile to the west of the screenshot.

[johndoe]

Well that's strange, when I follow the link it's right on I-25.  I wonder what I did wrong.

[johndoe]

Bumping this thread as I have a research request for the group!  I'm looking for the DDI with the smallest distance between the signals (measured between centerlines of ramps)... so for instance here's an "average DDI" location in Utah that seems to have about 775': https://www.google.com/maps/@40.725894,-111.9872419,535m/data=!3m1!1e3?entry=ttu

the "smallest" one I know currently in Reno with about 380': https://www.google.com/maps/@39.4930169,-119.7851811,136m/data=!3m1!1e3?entry=ttu

Can anyone find something less than 380'? thanks in advance

[SkyPesos]

I-278 and Northern Blvd in Queens is a noticeably compact SPUI that I've seen.

[Mr_Northside]

This SPUI between I-180/US-220 & US-15/Market St. in Williamsport is pretty compact.

https://goo.gl/maps/7WMDNu4fc7oxNbW99

[index]

There is a 2 lane DDI in Wyoming: https://maps.app.goo.gl/6Hhn2aU7VGvHVGRu7

Here is a partially two-lane DDI in Alcoa, TN:

https://www.google.com/maps/@35.7640285,-83.9881014,3a,60y,20.69h,90.36t/data=!3m6!1e1!3m4!1sZW2VdQM9uAG4YRTXP1tz3A!2e0!7i16384!8i8192?entry=ttu

I feel like I've seen one before on GSV that was fully two-lanes and controlled with stop signs, but I can't remember where it was.