Waterford -- The new Niantic River railroad bridge opened for the first time Friday.

Crews began to raise the bridge slowly in the mid-afternoon, stopping periodically to check the balance and the gears that operate the bridge.

Peter Finch, the project manager for Amtrak, said the gears, brakes and balance had all been checked before, but now they were being "put to the real test."

The structure that opens the bridge, the lift span, floated on a barge through the channel Monday and was set down on temporary supports. It was bolted into place during the week. Lead blocks were added to the counterweight that balances the bridge and two tugs moved the barge Friday.

If the lift span was unbalanced, Finch said, lifting it could have overloaded the motor, tripped the circuit breakers and possibly even damaged the machinery.

The new bridge opened using an auxiliary motor. It will remain open at an 82-degree angle so boats may pass underneath while construction continues.

Amtrak is building the two-track, electrified, railroad bascule bridge across the Niantic River between East Lyme and Waterford, 58 feet south of its current location. The channel will be blocked again next week when the beams for the east approach to the bridge are floated into place.

In May, contractor Cianbro/Middlesex Joint Venture will test the controls that will open and close the bridge. Amtrak will then shift rail traffic to the new structure, with the first track scheduled to open later this summer, followed by the second track in the fall. The old bridge will be demolished next spring.

The project is scheduled to be completed in May 2013. The $140 million bridge is being funded with federal stimulus money from the American Recovery and Reinvestment Act and Amtrak's capital budget.

j.mcdermott@theday.com