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Thursday, December 08, 2011 7:36:51 PM
At 80, George Washington Needs Bridge Equivalent of Hip Replacement
By CHRISTINE HAUGHNEY
The vertical suspension ropes on the George Washington Bridge will be replaced for the first time in its history.
The George Washington Bridge is a cathedral of steel cables and beams, a stark, glimmering span that has become a civil engineering landmark, not to mention the busiest vehicular bridge in the world.
But now, at 80, it is in need of a thorough overhaul.
On Thursday, the Port Authority of New York and New Jersey’s board authorized $15.5 million for repairs, part of the more than $1 billion that the project will eventually cost; agency officials want to clean the bridge’s four main cables and also replace, for the first time, the 592 vertical suspender ropes that hold up the roadway.
The overhaul is long overdue, Port Authority officials said; comparable bridges normally have their wires replaced after 70 years or so. It is also a fairly involved process: No more than three of the suspender ropes — each one is made up of 283 wires — that stretch from the bridge’s main cables to the roadway can be replaced at the same time, as removing more than that could destabilize the span.
Agency officials emphasized that the bridge was in no danger of collapsing because of the suspender deterioration. But they added that after spending $4.5 million over two years studying what repairs were necessary, it became clear that it was prudent to replace the ropes now. Waiting until there is a safety issue would require emergency repairs that would no doubt create what no driver on the George Washington Bridge wants: more traffic jams.
“We want to be sure that you don’t let the ropes to get to a point where you would have to take out a lane,” said Peter Zipf, the Port Authority’s chief engineer.
Although the agency has never replaced the bridge’s suspender ropes, which weigh 1,500 to 10,000 pounds each, depending on their length, the procedure is expected to be similar to the work done at the Golden Gate Bridge. For that project, a rolling platform, also known as a traveler, was placed atop the main cables, and then workers replaced the ropes, using temporary suspenders, jacking frames and jacks.
The project, which agency officials estimated would create 3,600 jobs, is daunting in its magnitude: the suspender ropes, if placed end to end, would be 32 miles long. If the 283 wires in each suspender rope were laid end to end, they would be 9,100 miles long — more than one-third of the circumference of the Earth around the equator.
The wires were a headache for the bridge’s creators back in the 1920s. Jameson W. Doig, a research professor at Dartmouth College and the author of “Empire on the Hudson,” which chronicles the history of the Port Authority, said the bridge’s chief engineer, Othmar Ammann, at one point considered using eyebars instead of wire rope to build the bridge.
The governor of New Jersey, Arthur Moore, pressured Mr. Ammann to use wire rope in the bridge’s construction because doing so would create jobs in New Jersey. But Mr. Ammann fought him until he was able to complete an engineering analysis. After finishing the analysis, he chose to use wire produced by the Roebling Company of New Jersey, run by the descendants of John A. Roebling, who designed the Brooklyn Bridge.
“It was a jobs issue,” Dr. Doig said. “It was a major issue in terms of whether the Port Authority could carry forward what it thought was the right way to design a bridge.”
By the time the bridge opened, in 1931, it had taken vast quantities of wire. Andrea Giorgi Bocker, the Port Authority’s resident engineer in charge of construction at the George Washington Bridge, said it took a year for the workers constructing the bridge to spin the 26,474 tightly coiled wires used in making each of the four main cables.
Replacing the suspension wire in stages will take eight years. Starting in 2013, the agency wants to clean up the massive anchorages tying down the bridge’s foundation, replace broken wires in the cables and replace the dehumidifiers in the chambers where the anchors are held.
The bridge’s main cables are still in pretty good shape. So workers will clean them up by scraping off their zinc-paste wrapping and adding a type of dehumidifier to the main cables. Then they will focus on the less-stable parts: they will replace all the suspender ropes, which are spaced every 60 feet.
“This is a structural engineer’s dream,” Mrs. Bocker said as she stood on the bridge on a recent misty afternoon, shouting over rumbling trucks and watching fog float swiftly onto the lower deck. She said she decided to become an engineer after visiting her father, who managed the George Washington Bridge when she was growing up. She rattled off facts and figures about the bridge as some might offer a baseball player’s batting statistics.
“Suspension ropes aren’t replaced every day,” she said. “In the case of the George Washington Bridge, it’s happening for the first time in its 80-year life. So it’s a once in a lifetime opportunity for an engineer to be a part of.”
Port Authority officials said they would pay for the repairs with revenue from tolls and fares.
When the repairs are completed, drivers, walkers and cyclists may notice that the rusted handrails and the sidewalks have been replaced. Most of the repairs will not be visible.
“You won’t feel any different,” Mrs. Bocker said. “You’ll probably see a shinier rope.”
http://www.nytimes.com/2011/12/09/nyregion/george-washington-bridge-cables-to-be-replaced.html?hp=&pagewanted=print
By CHRISTINE HAUGHNEY
The vertical suspension ropes on the George Washington Bridge will be replaced for the first time in its history.
The George Washington Bridge is a cathedral of steel cables and beams, a stark, glimmering span that has become a civil engineering landmark, not to mention the busiest vehicular bridge in the world.
But now, at 80, it is in need of a thorough overhaul.
On Thursday, the Port Authority of New York and New Jersey’s board authorized $15.5 million for repairs, part of the more than $1 billion that the project will eventually cost; agency officials want to clean the bridge’s four main cables and also replace, for the first time, the 592 vertical suspender ropes that hold up the roadway.
The overhaul is long overdue, Port Authority officials said; comparable bridges normally have their wires replaced after 70 years or so. It is also a fairly involved process: No more than three of the suspender ropes — each one is made up of 283 wires — that stretch from the bridge’s main cables to the roadway can be replaced at the same time, as removing more than that could destabilize the span.
Agency officials emphasized that the bridge was in no danger of collapsing because of the suspender deterioration. But they added that after spending $4.5 million over two years studying what repairs were necessary, it became clear that it was prudent to replace the ropes now. Waiting until there is a safety issue would require emergency repairs that would no doubt create what no driver on the George Washington Bridge wants: more traffic jams.
“We want to be sure that you don’t let the ropes to get to a point where you would have to take out a lane,” said Peter Zipf, the Port Authority’s chief engineer.
Although the agency has never replaced the bridge’s suspender ropes, which weigh 1,500 to 10,000 pounds each, depending on their length, the procedure is expected to be similar to the work done at the Golden Gate Bridge. For that project, a rolling platform, also known as a traveler, was placed atop the main cables, and then workers replaced the ropes, using temporary suspenders, jacking frames and jacks.
The project, which agency officials estimated would create 3,600 jobs, is daunting in its magnitude: the suspender ropes, if placed end to end, would be 32 miles long. If the 283 wires in each suspender rope were laid end to end, they would be 9,100 miles long — more than one-third of the circumference of the Earth around the equator.
The wires were a headache for the bridge’s creators back in the 1920s. Jameson W. Doig, a research professor at Dartmouth College and the author of “Empire on the Hudson,” which chronicles the history of the Port Authority, said the bridge’s chief engineer, Othmar Ammann, at one point considered using eyebars instead of wire rope to build the bridge.
The governor of New Jersey, Arthur Moore, pressured Mr. Ammann to use wire rope in the bridge’s construction because doing so would create jobs in New Jersey. But Mr. Ammann fought him until he was able to complete an engineering analysis. After finishing the analysis, he chose to use wire produced by the Roebling Company of New Jersey, run by the descendants of John A. Roebling, who designed the Brooklyn Bridge.
“It was a jobs issue,” Dr. Doig said. “It was a major issue in terms of whether the Port Authority could carry forward what it thought was the right way to design a bridge.”
By the time the bridge opened, in 1931, it had taken vast quantities of wire. Andrea Giorgi Bocker, the Port Authority’s resident engineer in charge of construction at the George Washington Bridge, said it took a year for the workers constructing the bridge to spin the 26,474 tightly coiled wires used in making each of the four main cables.
Replacing the suspension wire in stages will take eight years. Starting in 2013, the agency wants to clean up the massive anchorages tying down the bridge’s foundation, replace broken wires in the cables and replace the dehumidifiers in the chambers where the anchors are held.
The bridge’s main cables are still in pretty good shape. So workers will clean them up by scraping off their zinc-paste wrapping and adding a type of dehumidifier to the main cables. Then they will focus on the less-stable parts: they will replace all the suspender ropes, which are spaced every 60 feet.
“This is a structural engineer’s dream,” Mrs. Bocker said as she stood on the bridge on a recent misty afternoon, shouting over rumbling trucks and watching fog float swiftly onto the lower deck. She said she decided to become an engineer after visiting her father, who managed the George Washington Bridge when she was growing up. She rattled off facts and figures about the bridge as some might offer a baseball player’s batting statistics.
“Suspension ropes aren’t replaced every day,” she said. “In the case of the George Washington Bridge, it’s happening for the first time in its 80-year life. So it’s a once in a lifetime opportunity for an engineer to be a part of.”
Port Authority officials said they would pay for the repairs with revenue from tolls and fares.
When the repairs are completed, drivers, walkers and cyclists may notice that the rusted handrails and the sidewalks have been replaced. Most of the repairs will not be visible.
“You won’t feel any different,” Mrs. Bocker said. “You’ll probably see a shinier rope.”
http://www.nytimes.com/2011/12/09/nyregion/george-washington-bridge-cables-to-be-replaced.html?hp=&pagewanted=print
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