Looks like TDOT wants to make Exit 407 into a diverging diamond. They need to do something to deal with the traffic at high tourist season.
We already have a diverging diamond in Alcoa if you want to take a look.
Woot! I can’t wait for this to be built!
In case you don’t know, Diverging Diamond’s are the most wonderful thing the French made! (No, I’ve did some research. It originates from France. I wish America did something unique every now and then . . . )
The splendid part of the design is the flexibility. It can be used in a heavy urban area, or a more rural area, for a very cheap price as opposed to adding more lanes.
The one in Alcoa (not Maryville 
) is much more rural, and works wonderfully. Take my word for it. It’s a great design and should be used just about everywhere 
I edited my post to change Maryville to Alcoa. It is close to the border and I didn’t bother checking what side it actually was on.
And I think diverging diamonds are wonderful. We need more of them and more SPUIs as well.
Totally off topic, maybe Alcoa the town should change its name considering Alcoa the company is becoming less and less of a fixture in town. 
Well, one of the ramps is in a depressing state (and there are no exit signs, but that’s another story), because Maryville would need to get more right of way, which TDOT doesn’t feel like paying for.
However, in good news, Knoxville would be much more pleasurable to drive through (for me) if they added more.
I find SPUI’s to be expensive, huge, and more inefficient, as you still have a 4-phase light with a large neutral area. DDI’s only have 2 2-phase lights, with a very small neutral area. In fact, I’m willing to say, in more rural areas, DDI’s could have stop signs, and would work very well.
Took me a couple of minutes of watching the video to see how it works, but I’m very impressed by the capabilities of the DDI … there’s an interstate junction in my area that would be a lot better using a DDI. Of course, NYSDOT has never been accused of being progressive in terms of problem-solving, so I doubt that will ever happen … but it’s a great idea!