[CCs77]

Skeleton of Tappan Zee Bridge’s Successor Begins to Surface in the Hudson
http://www.nytimes.com/2014/09/19/ny...york.html?_r=1

TARRYTOWN, N.Y. — The shape of the new Tappan Zee Bridge is emerging from the green-gray waters of the Hudson River.

Steel piles drilled into the river’s muck and bedrock are beginning to reveal the trail the bridge will take to leap the three miles that separate Westchester and Rockland Counties.

The Erector Set-like skeleton of the first of 86 pairs of columns that will support the twin-spanned bridge rises 40 feet in the air near the Westchester side, waiting to be entombed in concrete that will be poured from an inventive floating concrete plant.

The numbers for the lyrical construction of the new bridge are impressive. Fourteen miles of cable in 192 separate strands will eventually be unspooled, enough to stretch from Tarrytown to the Bronx; the cable will be strung from the main-span towers to carry the steel deck. Before the end of the year, according to Ro DiNardo, the project’s general superintendent, and other officials, the first huge pieces of prefabricated steel deck are to be hoisted into place, the heaviest requiring a giant floating crane, which made its way to New York last winter from Oakland, Calif., through the Panama Canal.

I guess those pieces belong to the part of the bridge that is suported by pillars and not the main, cable stayed, span.

The full bridge will be supported by a total of 86 piers, or columns, most of them to bolster the long approaches to the bridge’s main span. The shortest piers, on the low shore of the South Nyack side, where the water is eight feet deep at low tide, are to rise 50 feet above the waterline; the tallest, near the bluffs of Tarrytown, will rise 130 feet. Unlike the main towers, the approach piers sit on prefabricated concrete tubs weighing 700,000 pounds each.

In total, 300,000 cubic yards of concrete, 30,000 truckloads, will be needed to build the bridge. To pour all this concrete, Tappan Zee Constructors has built a concrete plant on a 200-foot-long barge that can be ferried to wherever pouring is needed.

“We can mix the concrete right on the river so we don’t have to worry about concrete getting old,” said Mr. Waters, who has handled large construction projects in the Middle East and Europe.
Continue reading the main story Continue reading the main story
Continue reading the main story

The plant has three silos of cement and hoppers filled with the sand and stone to be mixed with it. It can produce 125 cubic yards of concrete per hour. A second plant will be towed over this month or early next month, as more concrete is needed. Officials say the floating plants are also environmentally congenial, greatly reducing the number of trucks that rumble through the residential neighborhoods on the two sides of the bridge.

Again, I guess that is part of the pillars of the approches of the bridge.