Diverging Diamond Interchanges

[Dirt Roads]

The DDI seems to me to be a solution in search of a problem. Having two "cross-over" locations is just asking for trouble...you're bound to get Grandpa Artie all confused and driving into incoming traffic.
<snipped>

Nineteen-year-old me was an idiot.

Actually, one of the reasons that an elderly relative quit driving was that the new DDI here was too confusing.  We are glad that she agreed before she tried it out.

[Scott5114]

Obviously, an elderly person can experience enough cognitive decline that driving in any sort of situation becomes inadvisable...but as Road Guy Rob points out in his video on DDIs, wrong-way crashes are comparatively rare in DDIs, because they're designed in such a way that driving into incoming traffic simply doesn't feel like the correct thing to do.

I still prefer SPUIs over DDIs, but I now feel like a DDI is often a preferable solution to a traditional diamond.

[ran4sh]

I like DDIs mostly because GDOT actually builds them. Before DDIs became popular, there were several congested service interchanges in Metro Atlanta and the only thing GDOT would ever do is study alternatives and not build anything, but when they found out about DDIs, they end up actually building it, possibly because of how much $ is saved by not replacing the existing bridges.

SPUIs are nice and Metro Atlanta has several, but GDOT hasn't built a new one in a long time.

[tolbs17]

SPUIs are nice and Metro Atlanta has several, but GDOT hasn't built a new one in a long time.

Does that include the highway going over the arterial? Because NCDOT has still built SPUIs like that on I-840 in Greensboro and I-295 in Fayetteville.

[Dirt Roads]

Newsflash.  Tonight (Feb 23, 2022) in its 6PM news hour, WRAL-5 in Raleigh is doing an expose on the safety issues related to the new Diverging Diamond Interchanges (DDIs) recently installed in the Triangle.  I am curious if their findings are any different than what has already been discussed here on AARoads.

[tolbs17]

Newsflash.  Tonight (Feb 23, 2022) in its 6PM news hour, WRAL-5 in Raleigh is doing an expose on the safety issues related to the new Diverging Diamond Interchanges (DDIs) recently installed in the Triangle.  I am curious if their findings are any different than what has already been discussed here on AARoads.

So that refers to the one built here. I still think it's safer compared to the previous design which was a death trap. If they are making complaints about it, then I might see it going to just a simple diamond or a Parclo which has 6 ramps.

[Great Lakes Roads]

https://www.google.com/maps/d/u/0/viewer?mid=1rCxreccEOiMavsoTJXUO0Ek2bd-9v_8&ll=46.23932735099809%2C-107.87050490000001&z=3

I have decided to make an updated map of every diverging diamond interchanges within the US. The actual DDI website is out of date... planning on adding the international DDIs at some point and let me know if I'm missing any DDIs on the map!

[CtrlAltDel]

https://www.google.com/maps/d/u/0/viewer?mid=1rCxreccEOiMavsoTJXUO0Ek2bd-9v_8&ll=46.23932735099809%2C-107.87050490000001&z=3

I have decided to make an updated map of every diverging diamond interchanges within the US. The actual DDI website is out of date... planning on adding the international DDIs at some point and let me know if I'm missing any DDIs on the map!

This is fantastic!

I was curious though about the difference between the yellow and green markers on the map. My guess is that yellow means not yet complete, but I wanted to be sure.

[Rothman]

There is a planned DDI north of Syracuse at I-81/NY 31.

[roadman65]

I see Raleigh area has two along I-40.  One at Jones Sausage and at NC 42. Both were constructed as part of I-40's widening.

[epzik8]

I taught my dad what these kinds of interchanges were called when we were at one in the Sarasota area this week.

[jdb1234]

The proposed Exit 9 on I-459 in Hoover was planned as a DDI.
I could be wrong, but I thought Exit 5 on I-10 (US 90A) in Pensacola was being reconstructed into a DDI.

[mgk920]

There are also several DDIs planned as part of the I-41 six laning project here in the Appleton, WI area.

Mike

[TheHighwayMan3561]

Add to the list

MN: I-494 at 34th Ave (Exit 1B).

[1995hoo]

You've got a few of the under-construction DDIs on FL-23, the First Coast Expressway. It appears there's another one under construction with a road that apparently doesn't yet exist. You can see the telltale outline of a DDI on the bottom part of this satellite image. I don't know how you'd describe this on the map index, though.

[tradephoric]

The thumbnail on this Youtube video pretty much says it all "27 lanes and still not enough".  More lanes lead to longer pedestrian crossings and longer clearance intervals which leads to longer cycle lengths.  This isn't a great design.

[Great Lakes Roads]

Add to the list

MN: I-494 at 34th Ave (Exit 1B).

Forgot about this one! It's now on my map.

https://www.google.com/maps/d/u/0/viewer?mid=1rCxreccEOiMavsoTJXUO0Ek2bd-9v_8&ll=46.23932735099809%2C-107.87050490000001&z=3

I have decided to make an updated map of every diverging diamond interchanges within the US. The actual DDI website is out of date... planning on adding the international DDIs at some point and let me know if I'm missing any DDIs on the map!

This is fantastic!

I was curious though about the difference between the yellow and green markers on the map. My guess is that yellow means not yet complete, but I wanted to be sure.

Here are my legends on the map:
Green- open for traffic
Orange- under construction
Yellow- proposed or under a timeline
Red- removed and replaced with a different configuration

Also, thanks for the support on this map! It took a lot of work, but I am happy that I did it for my own sanity (and I was bored one night)...

[Great Lakes Roads]

I could be wrong, but I thought Exit 5 on I-10 (US 90A) in Pensacola was being reconstructed into a DDI.

Apparently, FDOT is doing a "bridge replacement" to increase the clearance as well as accommodate future improvements of I-10 and Nine Mile Road.

The proposed Exit 9 on I-459 in Hoover was planned as a DDI.

Added this one onto the map. Construction should start sometime in 2025.

[johndoe]

Cool map GLR, thanks for making!  How'd you do this?!  Seems tough with so many different sources!  Here's another pretty good one: https://go.ncsu.edu/intersects-interchanges

I'd suggest adding the 'REAL' first DDI: Thurbers Ave @ I-95 in Providence, RI.

And once you've mastered the DDI list, feel free to do 'others that are somewhat weird' (SPUI, displaced left, CFI, unique u-turns) 

[PNWRoadgeek]

Oregon seems fairly fond of DDIs. They built their first one a couple years ago in Phoenix, a city around the Medford area. And they are working on a second one now as we speak, with this one in Marion County near the city of Aurora. Both of these are on I-5, which is nice for that road in particular, since it is a heavily trafficked road in both of those areas.

I have some personal thoughts on DDIs, as I think they are a neat way of controlling traffic flow. One of the rare times you see driving on the left side of the road in the US. It also seems like they are getting more and more common just looking at what state DOTs have in their lineups for future projects.

[jakeroot]

I'd suggest adding the 'REAL' first DDI: Thurbers Ave @ I-95 in Providence, RI.

I'm...staggered. While not a "complete" DDI, the resemblance to what we know as the DDI today is simply uncanny. I'm stunned this interchange isn't mentioned more often. It even predates the three (now two) DDIs in France by a good ten years.

[GaryV]

US-131 interchange with I-196 functions like a DDI, but with ramps instead of having any intersections. US-131 crosses over itself and has left exits and entrances. This has been there for decades.

[coldshoulder]

There is a DDI being constructed as a major renovation of the busy and congested intersection/interchange of OH-46 (surface road) and OH-82 (expressway) in Trumbull County near Warren, Ohio.  I believe it might be only the second or third DDI in Ohio.

https://www.transportation.ohio.gov/projects/projects/108547

[roadman65]

I see the next FL 23 First Coast Expressway expansion is building one for a new local road being added at Green Cove Springs north of SR 16 west of the city.

Neither road at the exchange were there prior to the construction and this one is one that will be built from scratch.

[Great Lakes Roads]

There is a DDI being constructed as a major renovation of the busy and congested intersection/interchange of OH-46 (surface road) and OH-82 (expressway) in Trumbull County near Warren, Ohio.  I believe it might be only the second or third DDI in Ohio.

https://www.transportation.ohio.gov/projects/projects/108547

7th DDI in Ohio...