Excerpt
JEFFREY BROWN (Newshour): Next, the second in our series of reports on how the attacks of 9/11 have affected people in this country and around the world.
Tonight, we look at the design and engineering of skyscrapers then and now.
NewsHour science correspondent Miles O'Brien has our story, produced in collaboration with the PBS program "NOVA."
MILES O'BRIEN: They don't build them like they used to. And for some, the story of 90 West Street in Lower Manhattan is concrete proof they should. On 9/11, debris from the Twin Towers rained down on this historic building next door. It was completely engulfed in flames.
JOHN NORMAN, New York Fire Department: We thought that the building was too dangerous to approach. And the fact that we had been told it had been evacuated when the towers were struck made a decision very simple for us, that we weren't going to fight that fire.
Retired FDNY Fire Chief John Norman is an expert on fighting high-rise fires. We met on the sidewalk in front of 90 West. Built in 1907, it is now an apartment building. Norman still marvels as how well it endured the conflagration 10 years ago.
JOHN NORMAN: This building had one steel beam that was affected by heat. It dropped a total of 1.5 inches. That was a horizontal column, so it was not a critical load-bearing member. The entire structural skeleton remained fine. And it's, as you see, still in use today.
MILES O'BRIEN: I'm sorry, one beam sagged? That's it?
JOHN NORMAN: One beam.
MILES O'BRIEN: Ninety West survived 9/11 because skyscrapers of that vintage were built like fortresses.
JOHN NORMAN: Everything was reinforced. You had a structural -- a heavy structural steel skeleton much like the towers. But these were protected with poured concrete or terra-cotta block tile, which gives tremendous resistance to fire. It's basically a redundant system of protection.
MILES O'BRIEN: Of course, skyscraper design and construction has evolved over the years. The newer glass skyscrapers are half as heavy per square foot as the old concrete fortresses.
Is it possible to do both, to build the gleaming glass towers and put enough technology in them to make them as safe as this building?
JOHN NORMAN: The glass towers are a problem. The glass skin is a weak point. But you can build buildings that are structurally stable and can withstand the fire long enough to allow the fire department to suppress it without giving in to the pressures of the economy. Yes, that's possible.
MILES O'BRIEN: And that is precisely what they're trying to prove with the design and construction of the $3 billion One World Trade Center.
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