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Milestone for New Tappan Zee Bridge: It’s Halfway Done Milestone for New Tappan Zee Bridge: It’s Halfway Done
(about 5 hours later)
TARRYTOWN, N.Y. — The building of the twin-span Tappan Zee Bridge, the first major new bridge in the New York area in half a century, has reached the halfway point.TARRYTOWN, N.Y. — The building of the twin-span Tappan Zee Bridge, the first major new bridge in the New York area in half a century, has reached the halfway point.
Already, more than a mile of concrete road deck has been laid, stretching from the bridge’s South Nyack end over the waters of the Hudson River. Thirty-five of the 43 pairs of piers that will hold up the 3.1-mile bridge are finished, with a framework of cornflower blue steel beams between many of them, so that more than half of the horizontal silhouette of the bridge is in place.Already, more than a mile of concrete road deck has been laid, stretching from the bridge’s South Nyack end over the waters of the Hudson River. Thirty-five of the 43 pairs of piers that will hold up the 3.1-mile bridge are finished, with a framework of cornflower blue steel beams between many of them, so that more than half of the horizontal silhouette of the bridge is in place.
Almost the entire steel skeleton should be completed by October, said Neil Napolitano, who manages work on the long approaches from both the Rockland and Westchester County shores.Almost the entire steel skeleton should be completed by October, said Neil Napolitano, who manages work on the long approaches from both the Rockland and Westchester County shores.
The toppling of a 256-foot crane on July 19 onto the roadway of the existing bridge, an accident that shut down traffic in both directions for five hours but remarkably caused no serious injuries, seems to have been a minor problem in the progress.The toppling of a 256-foot crane on July 19 onto the roadway of the existing bridge, an accident that shut down traffic in both directions for five hours but remarkably caused no serious injuries, seems to have been a minor problem in the progress.
In late July, workers began laying the bridge’s signature feature — the thick cables that will attach the main decks at midriver to eight 40-story towers and help firmly brace them like suspenders holding up a pair of trousers. The first of 192 cables, a 140-foot-long cord made up of strands of braided steel, was stretched from the eastern tower of the Rockland-bound span and a projecting section of road deck, locking into anchors built into the deck. By Aug. 1, four cables were strung, in whole or in part.In late July, workers began laying the bridge’s signature feature — the thick cables that will attach the main decks at midriver to eight 40-story towers and help firmly brace them like suspenders holding up a pair of trousers. The first of 192 cables, a 140-foot-long cord made up of strands of braided steel, was stretched from the eastern tower of the Rockland-bound span and a projecting section of road deck, locking into anchors built into the deck. By Aug. 1, four cables were strung, in whole or in part.
In all, the length of cable used will total roughly 14 miles. To passing travelers, the cables, sheathed in white plastic, might look like strings on a set of eight giant harps.In all, the length of cable used will total roughly 14 miles. To passing travelers, the cables, sheathed in white plastic, might look like strings on a set of eight giant harps.
“A cable-stayed bridge is a perfect mix of form and function,” said Sky Lee, the Oklahoma-born engineer supervising the construction of the main spans. “We are using cables to build the bridge, and ultimately it’s what everyone sees: the icon for the bridge.”“A cable-stayed bridge is a perfect mix of form and function,” said Sky Lee, the Oklahoma-born engineer supervising the construction of the main spans. “We are using cables to build the bridge, and ultimately it’s what everyone sees: the icon for the bridge.”
If everything goes according to plan, said Jamey Barbas, the engineer orchestrating the entire project for the New York State Thruway Authority, the first section should open to eight lanes of two-way traffic toward the end of next year. Demolition will then begin on the present Tappan Zee Bridge, which opened in December 1955, built cheaply during Korean War austerity for just $60 million ($531.5 million in today’s dollars). Its replacement is expected to cost just under $4 billion.If everything goes according to plan, said Jamey Barbas, the engineer orchestrating the entire project for the New York State Thruway Authority, the first section should open to eight lanes of two-way traffic toward the end of next year. Demolition will then begin on the present Tappan Zee Bridge, which opened in December 1955, built cheaply during Korean War austerity for just $60 million ($531.5 million in today’s dollars). Its replacement is expected to cost just under $4 billion.
Sometime in 2018, seven years after work began, the second section should be finished, carrying four lanes of traffic heading westbound toward Rockland on the northern stretch and four lanes heading east toward Westchester on the southern stretch. Bicyclists and pedestrians will have their own scenic lane, whose terminus, after some controversy, has been shifted from a residential neighborhood to a traffic circle in South Nyack.Sometime in 2018, seven years after work began, the second section should be finished, carrying four lanes of traffic heading westbound toward Rockland on the northern stretch and four lanes heading east toward Westchester on the southern stretch. Bicyclists and pedestrians will have their own scenic lane, whose terminus, after some controversy, has been shifted from a residential neighborhood to a traffic circle in South Nyack.
The bridge is not progressing as fast as the first optimistic schedule had it (the Thruway Authority once said the first span would be ready early next year), but a key to the relatively timely progress has been the strategic decision to prefabricate pieces of the replacement bridge on land, saving months of perilous work above the river. The large steel girders — 30 miles long in total — and 6,000 concrete roadway panels are assembled 14 miles upriver at Tomkins Cove near Bear Mountain or at Port of Coeymans, 10 miles south of Albany. They are then shipped to the Tappan Zee site by barge, where cranes lift them up and, guided by workers, swing them slowly into place.The bridge is not progressing as fast as the first optimistic schedule had it (the Thruway Authority once said the first span would be ready early next year), but a key to the relatively timely progress has been the strategic decision to prefabricate pieces of the replacement bridge on land, saving months of perilous work above the river. The large steel girders — 30 miles long in total — and 6,000 concrete roadway panels are assembled 14 miles upriver at Tomkins Cove near Bear Mountain or at Port of Coeymans, 10 miles south of Albany. They are then shipped to the Tappan Zee site by barge, where cranes lift them up and, guided by workers, swing them slowly into place.
Much of the concrete needed for piers, foundations, platforms and towers has been poured from floating plants on the river, requiring far fewer trips by truck through residential neighborhoods — 30,000 fewer, Ms. Barbas said.Much of the concrete needed for piers, foundations, platforms and towers has been poured from floating plants on the river, requiring far fewer trips by truck through residential neighborhoods — 30,000 fewer, Ms. Barbas said.
On a boat tour the other day, a reporter and photographer could see three barges lined up to deliver steel beams and other modular pieces to crane operators. A team of schedulers synchronize delivery of beams, concrete deck panels, nuts and bolts and other supplies as they are needed.On a boat tour the other day, a reporter and photographer could see three barges lined up to deliver steel beams and other modular pieces to crane operators. A team of schedulers synchronize delivery of beams, concrete deck panels, nuts and bolts and other supplies as they are needed.
Mr. Lee, 43, a civil engineer, said one challenge of the Tappan Zee’s parallel main spans was that they are “so isolated on the river.” Other bridges he has worked on, like the replacements of Gulf Coast bridges destroyed by Hurricane Katrina in 2005, had far more land access, while the central spans of the new Tappan Zee are in the middle of a three-mile-wide stretch of river. Work requires regular commutes by small boats from Tarrytown and deliveries by barge. Mr. Lee, a civil engineer, said one challenge of the Tappan Zee’s parallel main spans was that they were “so isolated on the river.” Other bridges he has worked on, like the replacements of Gulf Coast bridges destroyed by Hurricane Katrina in 2005, had far more land access, while the central spans of the new Tappan Zee are in the middle of a three-mile-wide stretch of river. Work requires regular commutes by small boats from Tarrytown and deliveries by barge.
“We’re in the middle of the Hudson River, so everything is multiplied by two,” he said.“We’re in the middle of the Hudson River, so everything is multiplied by two,” he said.
Because the work will take several years, his wife and high-school-aged sons moved with him to Westchester from the New Orleans area.Because the work will take several years, his wife and high-school-aged sons moved with him to Westchester from the New Orleans area.
A classic suspension bridge like the George Washington has cables that are anchored to the shore. A cable-stayed bridge like the new Tappan Zee has its cables anchored to tall towers, which bear the load.A classic suspension bridge like the George Washington has cables that are anchored to the shore. A cable-stayed bridge like the new Tappan Zee has its cables anchored to tall towers, which bear the load.
The construction of the four pairs of towers — massive wing-shaped concrete structures each 40 stories tall and leaning outward about 5 degrees — use an inventive engineering process that relies on what are called jump forms. The blue steel and wood forms — boxlike work rooms without a ceiling — allow carpenters and ironworkers to construct the successive concrete segments of each tower, one huge block of steel rebar encased in concrete piled atop another. Then after the concrete block is cured, or hardened, the forms can be elevated on vertical rails attached to the block, so the next block of concrete can be built atop the previous one within a safe enclosed space.The construction of the four pairs of towers — massive wing-shaped concrete structures each 40 stories tall and leaning outward about 5 degrees — use an inventive engineering process that relies on what are called jump forms. The blue steel and wood forms — boxlike work rooms without a ceiling — allow carpenters and ironworkers to construct the successive concrete segments of each tower, one huge block of steel rebar encased in concrete piled atop another. Then after the concrete block is cured, or hardened, the forms can be elevated on vertical rails attached to the block, so the next block of concrete can be built atop the previous one within a safe enclosed space.
The size of each block varies from 12 to 18 feet tall, with those at the top narrower than those at the bottom; it takes 26 lifts of a jump form to stack all the blocks for a tower that tops off at 419 feet tall. Though the towers are only two-thirds complete, crossbeams have already been extended from one tower to its sidekick to hold up the decks of the main spans. The cables, once pulled taut, will strengthen the grip.The size of each block varies from 12 to 18 feet tall, with those at the top narrower than those at the bottom; it takes 26 lifts of a jump form to stack all the blocks for a tower that tops off at 419 feet tall. Though the towers are only two-thirds complete, crossbeams have already been extended from one tower to its sidekick to hold up the decks of the main spans. The cables, once pulled taut, will strengthen the grip.
Seen from some angles, the towers look like four slender people doing an open-armed yoga exercise. Several holes in which the cables will be anchored are already visible. There will eventually be 12 holes each on flip sides of a tower, which means that 192 cables — some 11 inches in diameter, others two feet thick, with the longest segments reaching almost 800 feet — will be supporting the main deck.Seen from some angles, the towers look like four slender people doing an open-armed yoga exercise. Several holes in which the cables will be anchored are already visible. There will eventually be 12 holes each on flip sides of a tower, which means that 192 cables — some 11 inches in diameter, others two feet thick, with the longest segments reaching almost 800 feet — will be supporting the main deck.
Depending on where it is placed and the weight it must support, a cable can be made up of 30 or 60 or 80 strands of wire, each strand — three-fourths of an inch thick — itself made up of seven slim wires braided together. The cables are so heavy and stiff that they need to be threaded through the holes not by human hands but by a cranklike winch.Depending on where it is placed and the weight it must support, a cable can be made up of 30 or 60 or 80 strands of wire, each strand — three-fourths of an inch thick — itself made up of seven slim wires braided together. The cables are so heavy and stiff that they need to be threaded through the holes not by human hands but by a cranklike winch.
Supervising much of the work on the jump forms and cables are field engineers like Alessandra Rosso of the Bronx and John McCullough of Piermont, N.Y. Two or three times each day, they climb metal staircases to reach work areas in the towers that are 15 stories now and keep getting higher.Supervising much of the work on the jump forms and cables are field engineers like Alessandra Rosso of the Bronx and John McCullough of Piermont, N.Y. Two or three times each day, they climb metal staircases to reach work areas in the towers that are 15 stories now and keep getting higher.
“If you’re not in shape you get in shape pretty quickly,” Ms. Rosso said.“If you’re not in shape you get in shape pretty quickly,” Ms. Rosso said.
Still, 90 percent of her job is coordinating the ordering and delivery of materials, finding ways to get tools to where they are needed, talking to crane operators who must be nearby to hoist the materials to where they are needed but who must not be left to idle long. “Crane time is like gold around here,” she said.Still, 90 percent of her job is coordinating the ordering and delivery of materials, finding ways to get tools to where they are needed, talking to crane operators who must be nearby to hoist the materials to where they are needed but who must not be left to idle long. “Crane time is like gold around here,” she said.
At times the bridge has had two dozen cranes doing various jobs. The one that collapsed, which was using a vibrating hammer to force cylindrical support piles into the river bottom, was quickly replaced.At times the bridge has had two dozen cranes doing various jobs. The one that collapsed, which was using a vibrating hammer to force cylindrical support piles into the river bottom, was quickly replaced.
“It’s not going to impact our work,” Ms. Barbas said of the toppled crane.“It’s not going to impact our work,” Ms. Barbas said of the toppled crane.
This is Ms. Rosso’s first bridge. She previously worked on the East Side Access project that will connect Long Island Rail Road trains to Grand Central Terminal in Midtown Manhattan. So she has had to adjust to working at daunting heights in all kinds of weather.This is Ms. Rosso’s first bridge. She previously worked on the East Side Access project that will connect Long Island Rail Road trains to Grand Central Terminal in Midtown Manhattan. So she has had to adjust to working at daunting heights in all kinds of weather.
“The first time it’s definitely scary, but then it’s just work,” she said. “I think about the task, not the heights.”“The first time it’s definitely scary, but then it’s just work,” she said. “I think about the task, not the heights.”
Mr. McCullough, who last worked on renovating the Pulaski Skyway in New Jersey, seems simply awed by the scale of the job.Mr. McCullough, who last worked on renovating the Pulaski Skyway in New Jersey, seems simply awed by the scale of the job.
“This is 400 times bigger, everything is much bigger,” he said. “You have to have a Plan B if Plan A doesn’t work and a Plan C if Plan B doesn’t work.”“This is 400 times bigger, everything is much bigger,” he said. “You have to have a Plan B if Plan A doesn’t work and a Plan C if Plan B doesn’t work.”