Category: Diverging Diamond

At least, it was going well when I left last night at midnight. It’s been 15 hours since then, and I haven’t been back yet, so who knows? Maybe the bridge fell down (I doubt it; I probably would have heard about it).

Everybody and their sister is covering or commenting on this, which is very exciting! I plan to go back out to the site tonight around 7:00 or so to see how things are going.

One of the interesting items here is that, while my stamp is on the construction plans, I really have very little to do with the project any more. With a Design-Bid-Build process, the engineer (that would be Moreland Altobelli) does the design work, GDOT submits the bid documents, and the contractor does the building. The only time I get involved is when there’s a question on our plans.

I happen to be familiar with all the people who are working to make the construction process a success, but I’m just a spectator right now. However, I also happen to be the person who already has two engagements for presentations on Georgia Diverging Diamond Lessons Learned, so it behooves me to get back out there and learn some lessons.

I’ll be out there tonight, and tomorrow night, and Monday morning when it’s open to traffic. Looks successful so far!

Tonight at 9:00, that excavator you see in the image will start digging into the bank you also see in the image. By midnight, the surface will be level with the pavement you see, and the loop ramp from Ashford Dunwoody Road to I-285 eastbound will be no more (I refer you to other images I posted on Wednesday).

I’ll be on the project site off and on all weekend. While I have no control or responsibility here (I was the designer, but I’m not involved with construction beyond occasionally answering questions) this is the first diverging diamond in Georgia and I am very interested in how it turns out, obviously. I’m also slated to give at least two presentations this summer about what we learned during the process. Thusly, I should be on site to learn.

Expect some photos and dialogue on Monday, when the interchange is open and operating.

Do you frequent the top end perimeter? Do you know what I’m talking about?

If you don’t, then never fear, this post is not for you.

If you do, I recommend that you avoid the area of Perimeter Mall this weekend. On Friday evening, contractors will be closing all but one lane on Ashford Dunwoody Road southbound in front of the mall, in preparation for closing the bridge across I-285. You will be able to get on to and off of I-285, but you will not be able to cross the bridge. A detour route will be marked.

Still, I’d stay away. Except that I won’t. Because this is my project!

That’s right people! The Ashford Dunwoody Diverging Diamond Interchange will be a reality come Monday. That is, you’ll be driving in the new configuration; there will still be a lot of construction going on afterward. I plan to be out there during this weekend closure to watch the contractor compress about 3 weeks of work into 57 hours.

The closure begins at 9:00 PM on Friday and will remain in place until 5:00 AM on Monday. There are very steep penalties for every hour (and portion thereof) that the bridge remains closed after 5:00 AM. There are a couple big things and a gazillion medium sized things that have to be accomplished in that time, before traffic can resume.

The image here shows the big pavement or construction items that have to be finished. The loop ramp will be cut starting at 9:00 PM Friday and the rest of the ramp shown in yellow and red constructed. The yellow are areas that are “finished” with the red things that cannot be accomplished until the closure. The red mark across the bridge is an 8 inch concrete median that also cannot be poured until after the closure begins. Other tasks include taking down the old signals, milling and paving the entire bridge deck, putting down new striping, marking off the eventual concrete islands that divide the traffic (you can see them in the first image above), plus a host of other things.

This is a good project and will help to reduce the traffic congestion along Ashford Dunwoody Road. However don’t expect that relief to happen next week (remember, still lots of construction) and if I-285 is a mess, then the interchange will be a mess, too.

The details on the weekend detour and other things can be found at the Perimeter CIDs website. And if you want to seem some simulations, built by my friend Dave Sims (The Ultramind!), you can find them at my company’s website.