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.

Map of Exit 218 Travel Paths
Exit 218 Travel Paths (Photo: GDOT Concept Report)
Travel Times at Exit 218
Exit 218 Travel Times (Photo: GDOT Concept Report)

Previous Installments

May 29, 2018 update: the construction start date has been updated from September 2019 to late spring / early summer 2019.

Advertisements

One thought on “GDOT Part 5: The Diverging Diamond Interchange

Comments are closed.

Blog at WordPress.com.

Up ↑

%d bloggers like this: