Amtrak will close the new Niantic River Bridge for 48 hours beginning Sunday night to move the structure that opens the new bridge by half an inch.
The structure compressed more than the mathematical models predicted it would and now the lift span is too low.
Amtrak spokesman Cliff Cole said the Coast Guard recently approved the closure. Members of the local boating community had asked Amtrak to make other arrangements since a two-day closure at the height of the summer season would be a financial burden.
Cole said the contractor arranged for some of the charter boats to dock in New London.
The channel will remain open to marine traffic, but to go through boats will need to be able to pass underneath the lift span, which has a 16-foot vertical clearance restriction. The old bridge can be opened.
The lift span is scheduled to reopen at 9 p.m. Tuesday.