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3-Year Federal Study of 9/11 Urges Rules for Safer Towers by Jim Dwyer & Eric Lipton 6/22
After an exhaustive, three-year study of the collapse of the World Trade Center, a federal panel will call for major changes in the planning, construction and operation of skyscrapers to help people survive not only terrorist attacks but also accidental or natural calamities, according to officials and draft documents.
The recommendations, to be made public tomorrow, include a call for a fundamental change in evacuation strategies for tall buildings: that everyone should have a way out in an emergency, replacing the current standard of providing evacuation capacity for a few floors near a fire or emergency. The panel also called for sturdier elevators and stairways, and found that current standards for testing fireproofing of steel for tall buildings are flawed.
Taken together, the recommendations, by the National Institute of Standards and Technology, are likely to open an intense national debate over the costs of such changes and whether lessons for other skyscrapers can reasonably be drawn from the extraordinary events of Sept. 11.
The agency's proposals are not binding, but are meant to influence the policies of cities and states across the country. Many of them have become public in draft form during the three-year inquiry and have prompted fierce lobbying or objections from prominent engineers, building industry professionals, and the Port Authority of New York and New Jersey, which built the trade center. ………………………..S. Shyam Sunder, the engineer who oversaw the inquiry for the agency, said the investigators worked to identify issues of "safety for the vast majority of buildings" in fires, earthquakes, power losses and sudden hurricanes. The costs of the changes are unknown, but structural engineers suggested they would add 2 to 5 percent to development costs of ordinary buildings.
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The investigation also found that most building codes do not recognize that people on high floors are isolated and easily cut off from help during an emergency.
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The trade center towers, where 2,749 people died in the Sept. 11 attack, were only one-third occupied that morning. If the buildings had been full, it is likely that 12,000 more people would have died because of limited evacuation capacity, the investigation found.
Already, a proposal for wider exits - making it possible for people to leave faster but reducing the amount of rentable space - has been rejected by one major code-writing organization.
Others have suggested that it is folly to think different rules might have forestalled the collapses.
"They are leading the public down the wrong path," said Jon Magnusson, whose Seattle-based structural engineering firm, Magnusson Klemencic Associates, is the descendant of the company that designed the twin towers. "They are saying we are going to fix the codes in order to deal with Sept. 11th. The physics say that you can't do that."
Dr. Sunder says that is a mistaken reading of the investigation. The agency, he said, does not suggest that buildings should be able to stand up to airplane impacts. "It is more cost effective to keep terrorists away from airplanes, and airplanes away from buildings," he said.
……………………….
That research found no flaw in the design of the towers that was a critical factor in the collapse, Dr. Sunder said.
……………………………………
The recommendations also say that tall buildings should be designed to prevent "progressive collapse," avoiding a cascade of failures that can bring down a tower in seconds.
The study found that sprinklers, which can replace or reduce other fire-protection systems, should have a redundant water supply or power backups, to avoid being knocked out with one blow. Requirements for how well spray-on fireproofing should adhere to the steel columns also must be clarified, Dr. Sunder said.
The debate over integrating the proposals into building codes and practices will undoubtedly be intense. ………………….."We have to restore the public's perception of safety in skyscrapers," said Ms. Regenhard, whose son, a probationary firefighter, was killed in the attack.
The International Building Code Council moved last year to require that towers taller than about 40 stories have three hours' worth of fireproofing on structural elements, instead of two hours, but rejected proposals that would require wider stairwells and reinforced concrete or masonry walls in buildings over 25 stories.
The National Fire Protection Association, meanwhile, is expected to act in August to require stairwells that serve 2,000 or more people to be a foot wider than currently mandated, an official at the organization said.
Copyright 2005 The New York Times Company see attached for more
3-Year Federal Study of 9/11 Urges Rules for Safer Towers by Jim Dwyer & Eric Lipton 6/22
After an exhaustive, three-year study of the collapse of the World Trade Center, a federal panel will call for major changes in the planning, construction and operation of skyscrapers to help people survive not only terrorist attacks but also accidental or natural calamities, according to officials and draft documents.
The recommendations, to be made public tomorrow, include a call for a fundamental change in evacuation strategies for tall buildings: that everyone should have a way out in an emergency, replacing the current standard of providing evacuation capacity for a few floors near a fire or emergency. The panel also called for sturdier elevators and stairways, and found that current standards for testing fireproofing of steel for tall buildings are flawed.
Taken together, the recommendations, by the National Institute of Standards and Technology, are likely to open an intense national debate over the costs of such changes and whether lessons for other skyscrapers can reasonably be drawn from the extraordinary events of Sept. 11.
The agency's proposals are not binding, but are meant to influence the policies of cities and states across the country. Many of them have become public in draft form during the three-year inquiry and have prompted fierce lobbying or objections from prominent engineers, building industry professionals, and the Port Authority of New York and New Jersey, which built the trade center. ………………………..S. Shyam Sunder, the engineer who oversaw the inquiry for the agency, said the investigators worked to identify issues of "safety for the vast majority of buildings" in fires, earthquakes, power losses and sudden hurricanes. The costs of the changes are unknown, but structural engineers suggested they would add 2 to 5 percent to development costs of ordinary buildings.
………………………….
The investigation also found that most building codes do not recognize that people on high floors are isolated and easily cut off from help during an emergency.
…………………………………..
The trade center towers, where 2,749 people died in the Sept. 11 attack, were only one-third occupied that morning. If the buildings had been full, it is likely that 12,000 more people would have died because of limited evacuation capacity, the investigation found.
Already, a proposal for wider exits - making it possible for people to leave faster but reducing the amount of rentable space - has been rejected by one major code-writing organization.
Others have suggested that it is folly to think different rules might have forestalled the collapses.
"They are leading the public down the wrong path," said Jon Magnusson, whose Seattle-based structural engineering firm, Magnusson Klemencic Associates, is the descendant of the company that designed the twin towers. "They are saying we are going to fix the codes in order to deal with Sept. 11th. The physics say that you can't do that."
Dr. Sunder says that is a mistaken reading of the investigation. The agency, he said, does not suggest that buildings should be able to stand up to airplane impacts. "It is more cost effective to keep terrorists away from airplanes, and airplanes away from buildings," he said.
……………………….
That research found no flaw in the design of the towers that was a critical factor in the collapse, Dr. Sunder said.
……………………………………
The recommendations also say that tall buildings should be designed to prevent "progressive collapse," avoiding a cascade of failures that can bring down a tower in seconds.
The study found that sprinklers, which can replace or reduce other fire-protection systems, should have a redundant water supply or power backups, to avoid being knocked out with one blow. Requirements for how well spray-on fireproofing should adhere to the steel columns also must be clarified, Dr. Sunder said.
The debate over integrating the proposals into building codes and practices will undoubtedly be intense. ………………….."We have to restore the public's perception of safety in skyscrapers," said Ms. Regenhard, whose son, a probationary firefighter, was killed in the attack.
The International Building Code Council moved last year to require that towers taller than about 40 stories have three hours' worth of fireproofing on structural elements, instead of two hours, but rejected proposals that would require wider stairwells and reinforced concrete or masonry walls in buildings over 25 stories.
The National Fire Protection Association, meanwhile, is expected to act in August to require stairwells that serve 2,000 or more people to be a foot wider than currently mandated, an official at the organization said.
Copyright 2005 The New York Times Company see attached for more
