There are many ways to demolish a building, and some of them are spectacular: blowing it up from the inside so it collapses on itself, or smashing it to bits with a two-ton wrecking ball.
But here in Tokyo, a cheek-by-jowl city with many outdated high-rises and tough recycling and environmental restrictions, Japanese companies are perfecting what might be called stealth demolition. Some tall buildings are dismantled from the top down, the work hidden by a moving scaffold, others from the bottom up, the entire structure being slowly jacked down.
At times the techniques seem to defy gravity, or at least common sense, for although the buildings appear intact, they slowly shrink. The methods, which make for a cleaner and quieter work site, may eventually find favor in New York and other cities as aging skyscrapers become obsolete and the best solution is to take them down and rebuild.
The latest Tokyo high-rise to get the stealth treatment is the Akasaka Prince Hotel, a 40-story tower with a distinctive saw-toothed facade overlooking one of the city’s bustling commercial districts. Since last fall, its steel and concrete innards have been torn apart, floor by floor, starting near the top, by hydraulic shears and other heavy equipment. The building has been shrinking by about two floors every 10 days; this month it will be gone, to be replaced by two new towers.
Hideki Ichihara, a manager with Taisei Corporation, which developed the system being used to tear down the hotel, said the technique had environmental benefits and allowed for more efficient separation of metal, concrete and other recyclable materials. Another advantage is visual: The vanishing building looks normal for as long as possible. “We want people not to really see the demolition work,” he said. (...)
It is unclear whether demolition contractors in the United States will adopt any of the Japanese methods; even in Tokyo many buildings are demolished in more conventional ways. (With the new techniques, setting up the project can be more expensive, but the demolition often takes less time than with conventional methods.)
Herb Duane, a semiretired demolition consultant who writes frequently on the topic, said that Kajima’s ground-up technique might be problematic in a city like New York, where the weight of buildings is greater.
Bill Moore, a past president of the National Demolition Association and marketing director of Brandenburg Industrial Services, a demolition company, said that an Italian contractor had tried to interest American companies in a top-cap system that is similar to Taisei’s, to little effect. “Our environmental regulations are not that strict,” Mr. Moore said, and dust can be effectively contained by spraying with water.
One thing is clear, Mr. Moore said: Implosion by use of precisely placed explosives would not be used, nor would a wrecking ball. Both methods are largely forbidden in New York because of safety and environmental concerns, although this month officials allowed the first implosion in more than a decade, of an old Coast Guard apartment building on largely isolated Governors Island.
(In general, although implosion makes for great YouTube videos, it is appropriate in fewer than 2 percent of projects, Mr. Duane said. It is also occasionally unsuccessful, as it was last month in Brisbane, Australia, when a concrete silo had to be delicately nudged over by an excavator after explosive charges left it leaning precariously.)
Implosion is also outlawed in Tokyo, which is even more densely packed than New York. But the main impetus there for the new demolition techniques, said Dr. Seike of the University of Tokyo, was a recycling law that took effect in 2002.
In addition to valuable metals like steel, aluminum and copper, the law required that wood and concrete waste be recycled, even if the demolition contractors had to pay to do so. “People started to take recycling seriously,” Dr. Seike said. “And things have changed quite drastically with demolition.”
But here in Tokyo, a cheek-by-jowl city with many outdated high-rises and tough recycling and environmental restrictions, Japanese companies are perfecting what might be called stealth demolition. Some tall buildings are dismantled from the top down, the work hidden by a moving scaffold, others from the bottom up, the entire structure being slowly jacked down.
At times the techniques seem to defy gravity, or at least common sense, for although the buildings appear intact, they slowly shrink. The methods, which make for a cleaner and quieter work site, may eventually find favor in New York and other cities as aging skyscrapers become obsolete and the best solution is to take them down and rebuild.The latest Tokyo high-rise to get the stealth treatment is the Akasaka Prince Hotel, a 40-story tower with a distinctive saw-toothed facade overlooking one of the city’s bustling commercial districts. Since last fall, its steel and concrete innards have been torn apart, floor by floor, starting near the top, by hydraulic shears and other heavy equipment. The building has been shrinking by about two floors every 10 days; this month it will be gone, to be replaced by two new towers.
Hideki Ichihara, a manager with Taisei Corporation, which developed the system being used to tear down the hotel, said the technique had environmental benefits and allowed for more efficient separation of metal, concrete and other recyclable materials. Another advantage is visual: The vanishing building looks normal for as long as possible. “We want people not to really see the demolition work,” he said. (...)
It is unclear whether demolition contractors in the United States will adopt any of the Japanese methods; even in Tokyo many buildings are demolished in more conventional ways. (With the new techniques, setting up the project can be more expensive, but the demolition often takes less time than with conventional methods.)
Herb Duane, a semiretired demolition consultant who writes frequently on the topic, said that Kajima’s ground-up technique might be problematic in a city like New York, where the weight of buildings is greater.
Bill Moore, a past president of the National Demolition Association and marketing director of Brandenburg Industrial Services, a demolition company, said that an Italian contractor had tried to interest American companies in a top-cap system that is similar to Taisei’s, to little effect. “Our environmental regulations are not that strict,” Mr. Moore said, and dust can be effectively contained by spraying with water.
One thing is clear, Mr. Moore said: Implosion by use of precisely placed explosives would not be used, nor would a wrecking ball. Both methods are largely forbidden in New York because of safety and environmental concerns, although this month officials allowed the first implosion in more than a decade, of an old Coast Guard apartment building on largely isolated Governors Island.
(In general, although implosion makes for great YouTube videos, it is appropriate in fewer than 2 percent of projects, Mr. Duane said. It is also occasionally unsuccessful, as it was last month in Brisbane, Australia, when a concrete silo had to be delicately nudged over by an excavator after explosive charges left it leaning precariously.)
Implosion is also outlawed in Tokyo, which is even more densely packed than New York. But the main impetus there for the new demolition techniques, said Dr. Seike of the University of Tokyo, was a recycling law that took effect in 2002.
In addition to valuable metals like steel, aluminum and copper, the law required that wood and concrete waste be recycled, even if the demolition contractors had to pay to do so. “People started to take recycling seriously,” Dr. Seike said. “And things have changed quite drastically with demolition.”
by Henry Fountain, NY Times | Read more:
Image: Taisei-Seibu JV
