WEST COBB — Construction crews were working around the clock this week to rebuild a portion of Barrett Parkway in west Cobb, part of a larger, $21.7 million project that will ultimately make Barrett three lanes in each direction between Burnt Hickory Road and Cobb Parkway.

That three-mile stretch of Barrett Parkway, which runs past the Stilesboro Road entrance to Kennesaw Mountain National Battlefield Park, now has two lanes in each direction. The entire project, including the new additional lanes, should be open by next summer.

With 47,000 vehicles traveling the stretch each day, it is one of the busiest county-maintained roadways, said Dan McDuff, deputy director of Cobb’s Department of Transportation.

Last week, crews from GP’s Enterprises Inc. of Auburn, Ga., spent several days working on a smaller stretch of Barrett where the road’s structure had failed — between Stilesboro Road and Old Highway 41 — for 24 hours a day, and traffic was restricted to one lane in each direction.

Commissioner Helen Goreham, whose northwest Cobb district includes the stretch of Barrett Parkway being repaired, urged drivers to be patient.

“I wish there was a way to make improvements on roads without inconveniencing the public, but unfortunately there is no way around it,” she said. “We have to have lane closures.”

McDuff said the contractor was aiming to expedite the work and minimize traffic disruption.

“These improvements will have a huge impact on the heavy commuter volumes in this corridor,” McDuff said.

Besides the new lanes, crews will be adding turn lanes at intersections that have traffic lights, and building a sidewalk on the west side of the road and a trail on the east side.

Goreham said the project was originally included in the county’s 2005 Special Purpose Local Option Sales Tax package but had to be bumped to the 2011 SPLOST when money ran out.