Engineers Mull Trade Center Collapse
By PAM EASTON
Associated Press Writer
HOUSTON - Engineers investigating the collapse of the World Trade Center's twin towers are puzzled why the north tower stood for more than 90 minutes and the south tower for about 50 minutes after being hit by jetliners.
"It's amazing they didn't collapse immediately," Gene Corley, head of the engineering team, told the American Society of Civil Engineer's Convention on Friday.
Although the fire wasn't hot enough to melt the steel columns holding up the towers, the heat from the blaze was enough to weaken them and lead to a collapse, he said.
"Once it starts, the momentum just takes everything out," Corley said. "It's just an amazing amount of energy."
The time that elapsed between the planes crashing into the towers and their collapse enabled thousands of people to escape, and it is something engineers will be keeping in mind.
"We will be looking for things that might increase the time to get out," Corley said.
Corley noted four buildings around the towers partially collapsed, nine had major damage and 18 others had moderate damage.
The engineers hope to a have their initial report within six months.
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