Swiss Re Releases WTC Engineering Study

October 23, 2002

Swiss Re and the other insurers involved in the World Trade Center coverage dispute with master leaseholder Silverstein Properties, have released the comprehensive engineering study they commissioned to determine the causes of the twin towers’ collapse following the Sept. 11 attacks.

The study concludes that “the World Trade Center was a highly integrated complex and that the collapse of one tower in the World Trade Center complex would have severely compromised the future viability of the entire complex.”

Swiss Re, the other companies and Silverstein made their reports public, with the permission of the court that’s handling the lawsuit, following a great deal of inflamed rhetoric from the media which focused on their existence. The reports, which featured a lot of hysterical claims that the contents of the study “would never be revealed” and “the public will never know why the towers collapsed, etc.” probably weren’t true then and certainly aren’t true now.

The only reason they were withheld to begin with was because they formed part of a court proceeding. Swiss Re said that two weeks ago the companies had “provided all of their engineering materials — including the reports, the underlying data, computer models and engineering analyses — to NIST, the government organization that is investigating the engineering aspects of the tragedy to determine if there are safety lessons that can be learned from the way the World Trade Center complex held up in the attack.”

Among the conclusions in the study, developed by professional engineering firm Exponent Failure Analysis Associates (FaAA), were the following:
-The towers were designed as a pair and they relied on each other for
the structural stability to resist wind pressures.

-The collapse of a single tower would have destroyed or damaged virtually the entire sub-grade area that housed the common HVAC system; the electrical, water, sewage and steam systems for the complex; emergency control systems, and critical elements of the sprinkler system in addition to parking and retail space.

-The FaAA study also demonstrates that a standing tower would have been damaged in ways that would have been very costly to repair. The facade on two sides would have to be replaced for nearly the entire height of the tower, due to the damage from flying debris. Localized structural damage from heavier debris would need to be repaired. Fires would likely have been started in a standing tower, as they were in many other buildings close to ground zero, which would have caused both fire damage and smoke contamination.

Swiss Re also used the opportunity of the report’s release to reiterate its contention that the WTC attacks constituted one loss event and not two as “the World Trade Center complex collapse was the result of one attack on one complex.”

Complete copies of the FaAA study are available at Swiss Re by calling 212-317-5663.

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