Train service is not expected to be affected by major repair work that will begin soon on the Metro-North Railroad bridge over the Croton River, according to a Metropolitan Transportation Authority news release Wednesday.

The bridge carries four tracks over the river at the point where it empties into the Hudson River. Only the westernmost track, Track 4, is being replaced.

Metro-North railroad has already reconfigured the tracks between the bridge and the Croton-Harmon Station a quarter of a mile north so trains will be able to pull into the Track 4 platform, according to the news release.

In addition, the release states, the repair work will not impede canoers and kayakers' access to the popular upstream Croton River estuary or the Hudson.

In cooperation with the New York State Department of Environmental Conservation, Metro-North will use several environmentally protective measures, and the railroad will follow U.S. Coast Guard procedures for securing the barges from which all work will be performed.

No work in the water is needed because the two concrete abutments and the three piers were rehabilitated in the 1990s and are in good shape, according to the release.

The track is carried by four spans, each 100 feet long. Beginning in mid-June, when the track comes out of service for trains, each span will be demolished, hoisted onto a barge, removed and replaced one at a time on new concrete pedestals atop the existing piers.

Plans are for the new spans, weighing about 220 tons each, to be floated to the site at high tide to minimize disturbance to the river bottom, then hoisted into place by crane.

There will be no dredging or filling in the river. Equipment will be kept in the rail yard, where staging will occur. Recreational river access via the boat launch ramp and parking lot to the east of the tracks will not be disturbed. The barges will be positioned to allow boaters to access the Hudson River at all times, except during major lifting operations.

The $4.27 million contract on the project was awarded in December to Halmar International of Nanuet. It includes an incentive clause for early completion before June 26, 2014.

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The two inside tracks rest on a truss that was built in 1899. The two outside tracks rest on girders that were added in 1907.