South State Street eastbound traffic is being detoured to Lafayette Street.
The closure will continue through spring as road crews make repairs to the overpass that carries I-95 over the Metro-North train tracks.
A completion date hasn't been specified but the contractor has a six-month window to complete the work.
The initial portion of the project consists of removing and replacing the existing pier cap and supporting I-95 with a temporary structure.
Concrete repairs will be done concurrently on the existing piers, utilizing the temporary detour of South State Street.
The $4.1 million project was awarded to Blakeslee Arpaia Chapman Inc. of Branford in April, 2014.
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