Extensive construction work is underway at the busy intersection of I-285 and I-20 in Atlanta, Ga., a crucial junction for freight and commuters and one of the worst areas for traffic bottlenecks in America.
Crews are presently doing controlled blasting and contractors are installing drilled shafts, spread footings and driving piles for the foundation of a crossing that will make up part of the massive project. The blasting was done to remove granite bedrock for the many foundations.
The venture also entails reconstructing and widening several interstate ramps and adding several connecting and auxiliary lanes.
The revamp is needed due to heavy traffic demand. Several of the existing interchange ramps have geometric deficiencies or insufficient capacity. The interchange is a gateway to the south and western and northeastern U.S. It also links local communities to services and job centres.
The flyover ramp or bridge is a crucial part of the project. It is designed to ease congestion and improve mobility. The span will stretch more than half a mile and support two 12-foot lanes with wide inside and outside shoulders. The structure will consist of 20 separate spans, essentially individual sections supported by piers or columns.
The early stages of the project are focused on creating space for the new I-285 southbound corridor by removing the existing ramps entering and leaving the left side of the highway. Once the new I-285 southbound is constructed, replacement of the existing interstate pavement and construction of new access ramps can be completed to finish the project with less impact to traffic.
The Georgia Department of Transportation (GDOT) and its contractors are doing the controlled blasting within the interchange.
As can be imagined, a project of such significance requires meticulous planning and design by experienced professionals. To enable the blasting work to be done, vehicles are being slowed on the I-285 and surrounding connecting roads for short periods of time during weekdays.
The disruptions will continue as construction advances. Periodic lane closures will be implemented and new signage is to be installed for upcoming ramp changes. To mitigate problems for commuters and residents, GDOT is holding community meetings to share the progress.
The intersection is a heavily traveled interchange and ranked as the fifth worst bottleneck in the nation by the American Transportation Research Institute.
Several interstate ramps at the interchange will be reconstructed and widened. A combination of connecting and auxiliary lanes will also be added along I-20 west and I-285 north of the interchange.
Specific improvements include removal of a ramp entrance and exit ramps from the interchange, improvement of the geometric design and vertical grades, and construction of two-lane ramps. Crews will also build additional traffic lanes within the interchange and along local roads and modify and replace bridge structures and ramps in the interchange and over the Fulton County Railway and Chattahoochee River.
Construction on the project kicked off in 2024. Detention ponds were built to prevent flooding and retaining walls were installed to stabilize slopes for construction to move forward.
Legacy Infrastructure Contractors, consisting of C.W. Matthews Contracting Co. as the lead contractor, and Infrastructure Consulting & Engineering as the lead designer, is the project developer.
“The team at Legacy is comprised of local companies (with) over 250 years of experience,” explains Dan Garcia, president at C.W. Matthews. “We know the local market, we have a local workforce, we’re ready to tackle the challenge.”
The project is funded through a combination of state, federal and local sources, as well as private-partner financing.
To get a better handle on how to tackle the project, the team rewound the clock and surveyed records and the existing infrastructure. Technical concepts were then drawn up to maximize efficiency and minimize impacts to adjacent properties, streams and major utilities. The existing topography of the area was also used to reduce the overall stack height of the interchange.
Peter Graf, design manager at Legacy, says the new design will enable more traffic to pass through the intersection.
Design and construction experts collaborated to design several elements of the project to reduce labour and trucking while maximizing constructability. The schedule was speeded up by minimizing stages and prioritizing work that is not constrained by permitting or utility relocation.
“When we remodeled everything based on that improved design, we’ve actually improved the throughput of the interchange overall, but specifically in the I-20 area the delay was reduced by about 20 per cent. We also increased the corresponding vehicular speeds by about 10 per cent.”
To promote safety of workers and motorists, the work zone logistics plan consolidates locations where construction vehicle can access the highway.
Mike Nadolski, vice president of the design-build division at C.W. Matthews, says the staging plan maximizes the amount of work that crews can do.
“It’s also going to enable us to really centralize our construction access points,” he says.
