Construction to add a diverging diamond interchange (DDI) to Wade Green Road over Interstate 75 in Kennesaw will begin this summer, as early as mid-June. The project will include rehabilitation of the Wade Green bridge and is anticipated to last at least five months. Single-lane and full closures are expected in late September.
The Cobb County Department of Transportation’s plans to convert the overpass to a DDI resulted from studies showing increased congestion for traffic heading toward the I-75 southbound on-ramp and from the I-75 northbound off-ramp during the morning and evening peak hours, respectively. The DDI, which is designed to increase capacity, decrease congestion and enhance intersection safety while minimizing construction costs, will eliminate turning conflicts between vehicles accessing I-75. Eastbound and westbound motorists will be able to cross over on the bridge without facing opposing traffic. The completed DDI will have shorter signal times and will prevent vehicle queuing that has frequently extended along Wade Green Road to Jiles Road.
“Converting the Wade Green Road interchange to a DDI is vital to the traffic flow in the Kennesaw area, particularly in the morning and afternoon peak times,” said Jim Wilgus, director of the Cobb County Department of Transportation. “By converting to a DDI, we increase the overall capacity of the interchange and reduce delays.”
In addition to the rehab of the bridge, work will include median construction, signing, pavement markings and signalization. Crews will also:
- Widen the southbound on-ramp to I-75.
- Reconstruct the westbound lanes of Wade Green Road, beginning just east of the intersection with the I-75 northbound ramps.
- Add a right turn lane from the existing driveway of the BP gas station for I-75 northbound traffic.
- Add a left turn lane to the two Wade Green Road westbound through lanes approaching the intersection with the I-75 northbound ramps.
- Configure three westbound lanes of Wade Green Road to cross to the southern side of the existing Wade Green bridge over I-75.
- Add new sidewalks on the north and south sides of Wade Green Road.
The work for this DDI is comparable to that of the Cumberland area Windy Hill Road DDI, which opened this spring. The Wade Green DDI, however, will be constructed within the existing bridge parapets.
“Although the concepts of the DDI at both locations are the same, the Wade Green DDI addresses more of a capacity issue while the Windy Hill DDI also addressed a significant safety issue at that location,” Wilgus added.
The $5 million Wade Green DDI will be partially subsidized with more than $2 million in federal funds. Additionally, the project marks the first time the State of Georgia has allowed a local government to oversee a design-build contract using federal funding. The project will serve as a pilot program to determine if the state will proceed with this delivery method for other construction work.
“It will be the first design-build project primarily funded by the Georgia Department of Transportation that has been bid and built by a county, which is exciting for us,” Wilgus said.