A task force of North American building industry experts says there are ways to make tall buildings safer, but probably no way to prevent a building hit by a fuel-laden passenger jet from eventually collapsing. The task force was formed by the Council on Tall Buildings and Urban Habitat, in the wake of the September 11 attack against the World Trade Center in New York City.
The task force of structural engineers, architects, security experts and others says the World Trade Center towers performed heroically after being struck by two wide-bodied passenger jets filled with fuel. The towers remained standing for about an hour each, long enough for thousands of people to evacuate.
Council on Tall Buildings Chairman Ron Klemencic says the task force was meeting in Chicago Monday to discuss what can be done to make today's buildings safer from terrorist attacks, or any type of disaster or accident, as well as how to design stronger buildings for the future.
"Should we design buildings to withstand an asteroid? Well, we can obviously all say probably not," he said. "We are willing to take that risk. On the other hand, there is the do-nothing scenario, and I think we will probably say we are not willing to take that risk."
The task force says things that can be done are as simple as educating building tenants what to do in an emergency, including how to evacuate. Also, better alarm and security monitoring systems for everything from entrances and hallways inside, to plazas and air intake systems outside the buildings. Structural engineer Jon Magnusson says it is not practical to try to protect a building from a direct hit by a large airplane.
"Now that 767 that hit each of the World Trade Center towers weighed about 300,000 pounds (135,000 kg) and had a wingspan of 156 feet (47 meters)," he said. "A 747 has a wing span over 200 feet (61 meters) and a weight more than twice that amount."
Mr. Magnusson says the best way to protect tall buildings from airplanes is to improve security on planes to keep hijackers out of the cockpit. The task force plans to continue discussing ways to improve building safety, and make recommendations to the building industry in the months ahead.