Stonington — The state Department of Transportation will begin work Monday on an 18-month project to replace the bridge over Anguilla Brook on Route 234, a project that will require lane closures.

Traffic may experience delays from 9 a.m. to 3 p.m. and from 6 p.m. to 9 a.m. Monday through Friday, and from 6 p.m. to 10 a.m. on Saturdays and Sundays. Alternating one-way traffic will be in place, with a traffic control signal for the duration of the project.

Motorists are urged to obey the posted speed limit and to use caution through this and all other work zones. The nearly $2 million project is to correct the structural deficiencies of the existing bridge, which DOT officials called “functionally obsolete and hydraulically inadequate.”

Bridge work includes the replacement of the existing structure with a new 49-foot single span bridge that will consist of pre-stressed concrete beams with pile-supported integral abutments.

The project also involves roadway improvements at Route 234, including new bituminous concrete pavement at the approaches to the bridge, metal beam rail installation, pavement markings and new signs.

The contract was awarded to New England Infrastructure Inc. of Hudson, Mass., and is expected to be completed in November 2018.

State Sen. Heather Somers, R-Groton, on Friday hailed the start of “badly needed repairs” on the aging bridge.

“This is a bridge that has been in long need of repair,” Somers said in a news release announcing the project. “Hopefully, this is will be the first of many repairs to public structures in need.”