Crews will be working on the Casco Bay Bridge overnight starting next week.

Construction workers will apply concrete protective coating to most of the bridge starting Aug. 1 and will work through September, Maine Department of Transportation spokesmen Ted Talbot said Tuesday.

Maintenance will take place overnight, from 8 p.m. to 5 a.m., Talbot said. Traffic will be reduced from four lanes to two while workers are on the bridge, but the sidewalk will remain open.

“We are hoping for what we call minimal impact,” Talbot said. “We do not anticipate any issues; this approach lessens impact for motorists and pedestrians.”

The coating is part of normal maintenance for the drawbridge over the Fore River between Portland and South Portland. Sealing prevents water and salt from penetrating and corroding the steel bridge underneath, Talbot said.

Gordon Contracting of Sangerville was hired for the $442,000 job. Maintenance work is expected to be completed by Oct. 1.