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. While the agency has revised certain aspects of its findings on what precisely happened at the trade center, the package of recommendations makes it clear that the agency has essentially held firm on its emphatic and demanding safety agenda for the next generation of tall buildings in America.
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 study disclosed that critical design benchmarks and code standards used in the construction of the trade center -- the time it takes to walk down stairs, the distance separating stairways, and the fire-resistance tests -- turned out to have little relationship to the experiences or needs of people inside the towers. These findings, Dr. Sunder said, have broad application to buildings everywhere.
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 inquiry, conducted by more than 200 technical experts and contractors working for the agency, amounts to a 10,000-page autopsy of the trade center collapse. The report includes 25 pages of recommendations, which will be released for the first time as a full set in New York tomorrow.
''The whole purpose of the investigation was to make building occupants and first responders safer in future disasters and to learn whatever we could from what happened on 9/11,'' Dr. Sunder said. ''The recommendations will be reasonable and achievable.''
In the United States, building codes are generally adopted by local and state governments that use models developed by private groups like the National Fire Protection Association, established by the insurance industry, and the International Building Code Council, an organization of government construction regulators. Those two groups have set up committees to evaluate the recommendations.