GDOT Part 5: The Diverging Diamond Interchange

Ashford-Dunwoody at I-285 Diverging Diamond Interchange — Ashford-Dunwoody at I-285 opened in 2012 as the first DDI in Georgia.

This is part 5 and the final installment of the GDOT projects series after a joint meeting between Georgia Department of Transportation project managers and the Henry County Board of Commissioners.

I-75 Exit 218 Diverging Diamond Interchange :: Construction 2019

GDOT is moving forward with the interchange conversion at exit 218. The interchange will be rebuilt into a diverging diamond, or DDI, a model that has been successfully implemented at several locations in north metro Atlanta.

The basic concept of the DDI is that traffic travels on the left-hand side of the roadway over the bridge. This allows for left-hand turns to be made without crossing opposing traffic. This significantly improves safety and operational performance of the interchange.

The project is scheduled to start construction in late spring / early summer 2019. Construction will take 10-12 months to complete.

How much will traffic flow improve?

Analysis from GDOT shows an average reduction in delay of 25.5% in the year 2035, when compared to the current traditional build. These time savings will be greater when the project first opens. Photos from the GDOT Concept Report are included below.