NIST investigators made 31 recommendations based on their reviews of what happened in the twin towers and Building 7. The proposals called for substantial changes in how new high-rises are designed, built and maintained, and in evacuation and emergency response, though the researchers urged owners of existing buildings to also consider acting on the suggestions.
Turning the NIST recommendations into mandatory building and fire safety codes took several years. The voluminous "model" building and fire safety codes from which state and local governments pattern their own binding standards first had to be updated.
That process involves debate not just about the technical basis for the changes, but their applicability and cost, too. Most tall buildings probably are not terrorism targets. Some developers objected to the requirements, saying they might make skyscrapers prohibitively expensive.
"We're always trying to make a balance between cost and safety," said Shyam Sunder, who led the NIST investigation. "And we're always trying to make a trade-up in how safe is safe enough."
"The question is what I call the bookends," said Robert Solomon of the National Fire Protection Association, a non-profit group whose model fire codes are used by many cities. "Do we say [the Trade Center attack] is such an unusual occurrence that we're not going to do anything? Or do we really up the ante and go with all kinds of redundant systems and features?"
Significant changes in building codes
In the end, the National Fire Protection Association and the International Code Council, whose model building and fire codes are the blueprint for most U.S. communities, followed most of the 9/11 investigators' recommendations. They made significant changes in the 2009 and the upcoming 2012 codes, which apply to new high-rises. Ohio is preparing this fall to adopt its version of the 2009 codes, mirroring the changes.
