Mystic — The state Department of Transportation has announced that the expected 54-hour closure of the Mystic River drawbridge will take place from 7 a.m. Nov. 1 until 1 p.m. Nov. 3.

The bridge will be closed during that time to all vehicles, pedestrians and boats.

Stonington police said that through traffic will be detoured from Route 1, which spans the bridge, to Interstate 95 along Allyn Street in Groton and Route 27 in Stonington.

Traffic signs and other devices will be used to warn motorists of the bridge closure and guide them along the detour route.

The closure is needed to install a safety barrier on the span that will prevent cars from driving off the open bridge into the water from the Stonington side if they bypass the safety gates.

The 54-hour closure is the first of two that will be needed in the last season of the rehabilitation project, which is scheduled to be completed in April 2013. The second, which will occur next year to conduct the final balancing of the bridge, has not yet been scheduled.