A new noise study along Interstate 26 in North Charleston has found that the highway generates too much noise in the Northwood Estates neighborhood, but a sound barrier wall would cost too much.

“The conclusion is going to be, it doesn’t meet the Federal Highway Administration and Department of Transportation criteria,” Rhett Reidenbach of engineering firm Davis & Floyd, told members of North Charleston City Council during a recent update on road plans.

He said that, while noise levels exceeded federal guidelines at monitoring stations set up in the community, federal guidelines also set the maximum cost of sound walls at $30,000 per home that would benefit.

The estimated cost of a sound wall for Northwood Estates is roughly $7 million, according to Jim Armstrong, the county’s assistant administrator who oversees transportation and public works. That cost works out to about $45,000 per home.

Russell Coletti, president of the Northwood Estates neighborhood association, said the study results have not been presented to residents, and declined to comment.

County spokesman Shawn Smetana said the study isn’t finished, but county officials know what it’s going to say.

The noise study itself cost about $35,000 and was funded by Charleston County. The study covered the westbound lanes of I-26 along a roughly 1.7-mile stretch starting just beyond Ashley Phosphate Road and Exit 209-A.

A 1998 study reached a similar conclusion, about the costs being too high, but residents have kept up the fight. Not far away, on the opposite side of Ashley Phosphate Road, residents of the Midland Park neighborhood have also been pressing for a noise wall, along the eastbound side of I-26.

The Midland Park community was not a part of the recent noise study. Previous study found that noise from the highway is excessive, but funding has not been found for a sound wall.

Sound walls in some other communities, such as Mount Pleasant, have been paid for with local funds — an option that North Charleston officials have not embraced.