Gold Award – Northwest Corridor Express Lanes, Atlanta, GA
Contractor: Archer Western Construction, LLC*
Owner: Georgia Department of Transportation
Engineer: Parsons Transportation Group
The Northwest Corridor Express Lanes on I-75 and I-575 in Cobb and Cherokee counties in Georgia, just northwest of Atlanta, represented the largest infrastructure project in the Georgia Department of Transportation’s history and the first project awarded as a design-build-finance project.
The project entailed 29.7 miles of reversible, managed toll lanes along the expressway and included 1.2 million CY of unclassified excavation, 140,000 LF of drainage, 328,000 SY of concrete paving, and 280,000 LF of concrete barrier. The project also included construction of 1.4 million sq. ft of sound wall, 1 million sq. ft of bridge deck on 40 bridges, and 900,000 sq. ft of retaining walls.
Because the large-scale project is directly adjacent to one of the highest volume interstate highways in the Atlanta metropolitan area, a significant amount of work was performed at night. Dedicated construction entrances and exits were required along the corridor. The use of engineered traffic control plans and dedicated construction access points, the risk of construction traffic entering and exiting the busy interstate was minimized and construction activities were separated from the traveling public.
Weather affected construction on 177 days over the five years of the project. To recover these lost days, the concrete paving team implemented two separate strategies:
- Roadway shoulders were paved before the mainline paving to allow the concrete barrier wall slip forming operation to be advanced in the schedule.
- An additional paving operation—crew and equipment—was deployed to allow double shifts for the paving operation. This accelerated the mainline paving while also allowing other crews to pave shoulders.
At the beginning of the project, three different mix designs were created, with the percentage of manufactured sand differing in each mix. The three mixes were: 100% manufactured sand; 80/20 manufactured/natural sand; and 60/40 with manufactured/natural sand. Ultimately, the project team elected to use the 60/40 mix design, which cost more, but was selected to increase workability and ride quality.
With the completion of this mammoth project, motorists have an exceptional and durable highway that will provide years of service.
* ACPA member.