Monday, August 08, 2011

Traffic of the future

So they want to put one of these on Ashford-Dunwoody road?

This image of a typical diverging diamond actually comes from
the Missouri Department of Transportation, but I found it at

‘Diamond' interchange coming to I-285 in Dunwoody |

I had to go see both the Wikipedia entry for diverging diamond interchanges and a YouTube video of a diverging diamond visualization before I got a feel for exactly how this would work. If you've exited GA 400 at Lenox Road, or Peachtree Industrial at Tilly Mill or Jimmy Carter Boulevard, you may have a head start. At those intersections, when you enter or exit the limited-access highway, LEDs embedded in the street show you that you drive a significant distance on the "wrong" side of the street. I consider those intersections "training wheels" for this, where even surface traffic traverses the entire under/overpass on the "wrong" side. 

It's almost guaranteed that for us Atlanta drivers, our first reaction is going to be that this can't possibly work. Look how much trouble we have with those "wrong side" HOV ramps at I-75 and Northside Drive.

But this is a completely different perspective on what an intersection has to accomplish. Sure, a traditional cloverleaf would be ideal, easier to visualize. But you need a lot of room on all sides to build one of those, and you're certainly not going to find that at Ashford-Dunwoody road. This, you can do without even rebuilding the bridge. And I sure can't think of an intersection anywhere in Atlanta that needs help worse than this one.

And Springfield, MO certainly seems happy with theirs.

I can't remember the last time I was excited about a highway intersection. I can't wait to try this thing!

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