Blueprint to terror-proof nation's skyscrapers
Controversial new study recommends 'hardened' elevators, wider stairwells, and fireproofing after 9/11.
NEW YORK — Tall buildings in the United States could be easier to evacuate, less vulnerable to fire, and sturdier structurally as a result of the 9/11 terrorist attacks.
After an exhaustive three-year analysis of the causes of the collapse of the World Trade Center's Twin Towers, the National Institute of Standards and Technology (NIST) is recommending sweeping changes to building codes around the nation to ensure that in the case of tragedy - fires and other natural disasters as well as terrorist attacks - the maximum number of people will be able to survive.
The 30 recommendations from a draft report include increasing the width of stairwells so as workers evacuate there will be enough room for the fireman going up. It also suggests that elevator shafts be "hardened," and one set aside to be used exclusively by emergency responders. And it calls for structural improvement to prevent the kind of kaleidoscopic collapses at the Twin Towers.
The recommendations, which were made at a press conference near the World Trade Center site, are expected to generate a fair amount of controversy in the construction and building code community, in part because such changes could increase the cost of construction. But for the engineers who undertook the study, the main concern is safety.
"[The] NIST strongly urges the building and fire safety communities to give immediate and serious consideration to these recommendations in order to achieve appropriate improvements in the way buildings are designed constructed, maintained, and used in evacuation and emergency response procedures," says Dr. Shyam Sunder, the lead investigator at the NIST which is part of the US Department of Commerce.
Among the 30 recommendations:
• Efforts to limit how much tall buildings sway during strong wind and earthquakes. According to the NIST, such limits are currently not a requirement of many building codes.
• Dividing up a building with fire doors to limit the amount of air that can feed a fire, especially in office towers with large open floor plans.
• Improvement of fireproofing, including methods to ensure it continues to adhere to structural beams despite vibration.
• Better emergency intelligence, including systems to track emergency personnel inside of buildings.
The recommendations are not expected to change the look of the nation's urban skylines. The changes, if adopted in local building codes, would simply improve internal safety. Some engineering experts greeted the study as a much-needed scientific analysis of code and structural requirements.
"A lot of regulations in fire safety have come through good intentions, committees trying to do the right thing, but really lacking technical input," says James Quintiere, a professor of fire protection engineering at the University of Maryland.
Dr. Quintiere also contends that the NIST's determination that the fire was a primary cause of the building's collapse indicates there are deficiencies in fire safety codes that must be addressed. "The public should demand that they be looked at carefully," he says.
Some engineering experts contend that some of the recommendations can be applied to existing buildings as well as new construction, for instance the hardening of elevator shafts. But they also caution that costs must be taken into consideration.
"Clearly you have other interests that are concerned with affordability of construction, and that has to be balanced against the value, the public benefits of these improvements, because they will cost," says Tom Frost, a senior vice president for technical services at the International Code Council, a private not-for-profit association whose mission is producing model construction code outside of Chicago. "These all have to be subject to the reality of cost/benefit [analysis]. You can design a building to do almost anything if you have enough money. "
This report will be followed shortly by an analysis of why 7 World Trade Center also collapsed on Sept. 11. It was the site of the city's emergency center and included diesel fuel for auxiliary generators. However, the current draft report recommends that fire resistance standards should take into account the storage of such fuel.