East Lyme — The crews working on the Niantic River Bridge are digging a trench in the channel for cables and getting ready for a large barge with pieces of the lift span to arrive.

The projects in the water have to progress steadily through the winter so the major work in the channel will be finished by mid-April, when boat traffic picks up, Peter Finch, the project manager for Amtrak, said.

Amtrak is building a two-track, electrified railroad bascule bridge across the Niantic River, 58 feet south of its current location between East Lyme and Waterford. Finch led a tour of the work site on Thursday for U.S. Rep. Joe Courtney, D-2nd District, East Lyme officials, including First Selectman Paul Formica, and others interested in the project.

The $125 million project, funded with both federal stimulus funds from the American Recovery and Reinvestment Act and Amtrak's capital budget, is expected to be complete in May 2013. The clearance under the bridge will be 16 feet instead of 11.5 feet, and the channel underneath will be widened to 100 feet instead of 45 feet.

It is the largest recovery act Amtrak project in the nation, Courtney said. Formica said that the bridge replacement project is significant for the entire northeast corridor and the improvements to the boardwalk and beach will make East Lyme even more of a destination.