East Lyme - The crews at the Niantic River Bridge project site took the first major step this week in assembling the structure that will open and close the new bridge.

Friday morning, crews fine-tuned the position of a massive "heel girder," one of two that were put into place this week using two large cranes. Their function is to hold the solid lead blocks that act as counterweights when the bridge opens, as well as a gear that will open and close the bridge. Eventually they will connect to the lift span on which the trains travel.

"It's a big deal getting these put into place, no doubt about it," said Peter Finch, Amtrack project manager.

Because the girders are awkwardly shaped with one end resembling the heel of a shoe, it's tricky to determine the best place to lift them without doing any damage and at the same time maintaining a balance, Finch said.

A rigging expert for contractor Cianbro/Middlesex Joint Venture Team spent three months working on the plans.

In the project office, Finch said, the team uses a three-dimensional computer program, much like a video game, to look at the bridge from all angles to make sure everything is placed properly. Pipes containing electrical cables, for instance, can't be put where they would interfere with the bridge opening, Finch said.

"Everything has to work together," he said.

The channel was closed this week because the barge holding the crane blocked it. The contractor worked from the bottom up, first placing the pinion gear, then the gear rack, a floor beam and finally the heel girders.

The bright green-and-orange-pinion gear engages the gear rack to open and close the bridge. The parts painted green don't move; the orange ones do. A shaft eventually will connect it to the electrical and mechanical components that drive the bridge.

It took roughly three hours to position each girder. They had to be lifted from the crane barge, turned upright in the air, swung around the operator's house and then rotated again to be set into place on new bronze bearings.

Finch said the work was progressing on schedule. He has asked the Coast Guard whether the next channel closure, planned for early March, could be a few days earlier to move other large parts into place sooner than predicted.

The rest of the steel parts for the lift span will be assembled over the next month and a half on a floating barge. Once complete, the lift span will be raised using hydraulic jacks, floated into place and fitted into the heel girders.

j.mcdermott@theday.com