Major work begins on one of metro Atlanta’s worst traffic bottlenecks


After months of preliminary work, construction has begun in earnest on a fix for one of metro Atlanta’s worst traffic bottlenecks.

The new I-285 interchange at Ga. 400 will take almost three more years to complete. When it’s done, state transportation officials say it will make commuting easier for hundreds of thousands of people.

But they say the immediate traffic relief is just the beginning of its benefits.

The interchange sits at the center of what will become an extensive system of express toll lanes radiating out from the northern half of the Perimeter. That system will eventually allow motorists from Acworth to Buford to bypass the stop-and-go traffic that confounds commuters.

The I-285/Ga. 400 interchange is the linchpin of that system.

“This interchange is critical,” said Joe Carpenter, director of public-private partnerships for the Georgia Department of Transportation. “These improvements are going to accommodate traffic 20 years into the future.”

It’s been a year since Gov. Nathan Deal and other state officials broke ground on the $800 million interchange. Since then, workers have cleared trees, relocated utilities and installed row upon row of silt fences for erosion control.

Major construction officially began last month with work on a new Mount Vernon Highway Bridge over Ga. 400.

420,000 vehicles a day

The I-285 interchange at Ga. 400 crisscrosses one of the largest employment centers in metro Atlanta.

The Perimeter Community Improvement Districts house about 5,000 companies and 33 million square feet of office space. Nearly 100,000 people live in the area, and another 123,000 work there. It’s home to Fortune 500 companies, several hospitals and the state’s second-largest shopping mall.

Throw in tens of thousands of commuters who are just passing through, and you’ve got a recipe for rush-hour misery. About 420,000 vehicles a day pass through the interchange, which was designed to accommodate 100,000.

“Rush hour” around the interchange typically lasts three to four hours each morning and afternoon, according to an environmental assessment of the project. Even in the middle of the day, traffic often backs up on both highways.

What’s more, closely spaced interchanges along I-285 (including Roswell Road, Glenridge Drive, Ga. 400, Peachtree Dunwoody Road and Ashford Dunwoody Road) leave many motorists weaving in and out of traffic as they enter and exit the highway.

In short, traffic in the area is a mess.

GDOT’s solution is to completely rebuild the interchange with a series of new collector-distributor lanes and flyover ramps that will carry more vehicles and eliminate some of the traffic weaving.

It sounds simple, but the construction will sprawl 4.3 miles along I-285 and 6.2 miles along Ga. 400. In addition to the new Mount Vernon Highway bridge, it will include a new diverging diamond interchange at Ga. 400 and Abernathy Road.

Over the next year, motorists will see work on both of the Mount Vernon and Abernathy projects and on the new collector-distributor lanes. Much of the construction will be completed in 2019.

If all goes well, the work will be finished by summer 2020. But the new lanes will open as they’re completed, so motorists should see some benefit before construction is done.

GDOT estimates the project will cut drive time through the interchange substantially. For example, rush-hour travel time on Ga. 400 from Northridge Road through the interchange may decrease by up to 10 minutes, depending on the time of day.

GDOT Commissioner Russell McMurry said the interchange will be “a little bit of a relief valve for the top end of the Perimeter.”

Long-term traffic relief

But McMurry said the full impact won’t be felt for more than a decade. That’s how long it will take GDOT to finish building 120 miles of express lanes that are a big part of the state’s plan to tackle Atlanta’s awful traffic congestion.

The express lanes will allow motorists to cruise along at 45 mph or more if they’re willing to pay a toll. As more drivers use the express lanes, state transportation officials say, they will free up space in the regular lanes, benefiting even drivers who don’t want to pay.

Express lanes already exist on parts of I-75 in Clayton and Henry counties and I-85 in Gwinnett. The Northwest Corridor Express Lanes will open on I-75 and I-575 in Cobb and Cherokee counties next summer, followed by an extension of the I-85 lanes next fall.

The new I-285/Ga. 400 interchange will pave the way for the next wave of express lanes on Ga. 400 and on the northern half of the Perimeter.

“Think about how the puzzle pieces fit,” McMurry said. “There’s 285/400 first. Then the (Ga.) 400 lanes. Then the 285 express lanes.

“We’ll have a system where you can access the express lanes all on the top end (of the Perimeter) and all the radial routes,” he said.

Thanks to the I-285/Ga. 400 interchange construction, traffic is likely to get worse before it gets better. To minimize the impact, much of the work will occur at night or on weekends. But there will still be detours and lane closures, so drivers should expect delays.

“We’re just beginning to see those impacts,” said Ann Hanlon, executive director of the Perimeter Community Improvement Districts. “In 2018, I think we’re going to feel the impact even more.”

The improvement districts have taken steps to alleviate construction traffic, pushing the use of mass transit and contacting employers to encourage them to let commuters to work from home.

When the interchange is complete, Hanlon believes the short-term pain will have been worth it.

“I really think it’s going to be a game changer,” she said. “I think we’ll see a huge improvement all around the region.”

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The AJC's David Wickert keeps you updated on the latest in what’s happening with transportation in metro Atlanta and Georgia. You'll find more on myAJC.com, including these stories:

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