Roswell-area commuters who use GA-400’s northbound flex lane near Windward Parkway will lose that option starting Dec. 13 as construction advances on the highway’s express lanes project.

The permanent closure affects about three-quarters of a mile between a point just south of the Webb Bridge Road overpass and Exit 11 at Windward Parkway, according to WSB-TV. The shoulder lane currently provides additional capacity during peak travel hours.

After the closure, Georgia Department of Transportation contractors will remove flex lane signs and striping and install a temporary concrete barrier.

Four northbound travel lanes will remain open. Drivers exiting at Windward Parkway should use the right lanes, while through traffic should continue on the main roadway.

The work is part of the SR 400 Express Lanes Project, which will add approximately 16 miles of optional toll lanes between North Springs MARTA station in Sandy Springs and McFarland Parkway in Forsyth County.

The project calls for two express lanes in each direction between North Springs and McGinnis Ferry Road, then one in each direction to McFarland Parkway, according to GDOT’s project fact sheet. Construction is underway at multiple locations, with the lanes expected to open in 2031.

GDOT’s private partner is SR 400 Peach Partners. The public-private partnership represents approximately $11 billion in total investment, according to Mayer Brown, which advised the consortium on financing.

The flex lane closure follows other traffic changes along the corridor. In August, GDOT closed the original southbound Exit 5 in Sandy Springs and replaced it with temporary ramps serving North Springs MARTA station and Abernathy Road and Hammond Drive.

“So over the next five years, there’s going to be more traffic shifts. As with this one, we plan to make sure the public knows well ahead of time,” GDOT spokesperson Joe Schulman told WSB-TV in August.

GDOT advises drivers to slow down and allow extra travel time through the work zone. Construction schedules may change because of weather or other conditions.

Drivers can check traffic updates by calling 511, visiting 511ga.org or using the Georgia 511 mobile app.