Cobb County Government

Windy Hill Road Diverging Diamond Interchange

The Windy Hill Road Diverging Diamond Interchange (DDI), substantially completed in spring 2017, decreases traffic congestion and accident rates at the ramp intersections of Windy Hill Road and I-75 by decreasing the conflict points. The Federal Highway Administration estimates 650 left turns can be made per hour via the DDI, nearly twice the number in a conventional left turn.


Motorists can no longer be able to turn right onto the west side of Interstate North Parkway. The DDI is designed to ease the flow of heavy traffic by eliminating a left turn signal, while allowing two directions of traffic to cross on opposite sides of the bridge on the I-75 overpass. Construction began in January 2016.


Windy Hill DDI Brochure

DDI Diagram

I-75 Overpass Improvement Plans