WestCon Tribune

 

As we saw on the morning of 9/11, hijacked 767s were flown into both of the 110 story towers of the World Trade Center. While both towers absorbed the impacts without collapse, the steel framing of the towers quickly lost strength from the intense heat of the ensuing fires and both towers collapsed to the horror of us all. During the collapse, much of the exterior structure of the towers broke free and fell onto surrounding buildings. Four 9-story, low-rise buildings in the WTC complex were partially crushed by that falling structural debris, while other buildings several hundred feet away sustained serious structural damage. The 47-story, WTC7 building immediately north of the site collapsed several hours later as a result of fire damage. In excess of 10 million square feet of building space was lost. Total debris weight is estimated to be 1.2 million tons - 2.4 billion pounds.

Simultaneously a third plane plowed into the Pentagon, igniting fires and collapsing a portion of that enormous structure.

Within minutes of these events, FEMA activated its Urban Search and Rescue (USAR) teams nationwide, dispatching teams to New York City and Washington D.C. Those teams began searching partially collapsed areas and void spaces for possible trapped victims. In both New York and at the Pentagon, despite public statements, it became apparent early on that there were no survivors trapped in the rubble. Thus most of the USAR teams deployed to the Pentagon and the World Trade Center knew from the outset they would be assisting with body recovery, but were ready to do whatever possible to contribute to the overall recovery effort.

The USAR program was set-up in the early 90s to establish specially trained rescue teams to extract victims trapped in structures that had collapsed as a result of natural disasters such as earthquakes or hurricanes. Each team is comprised of 62 positions including specialists in rescue, technical and canine search, communications, logistics, hazardous materials, medical and structural engineers. The teams are outfitted with tons of equipment for breeching, shoring, demolition, and rescue and receive training in techniques and methods of finding and extracting victims from all types of collapsed structures. Teams are ready to be on an airplane within six hours of notification and have supplies to be self sufficient for 72 hours. Three teams are based in Northern California: California Task Force 3 (CATF3) in Menlo Park, CATF4 in Oakland, and CATF7 in Sacramento.

JOHN OSTERAAS is a Principal Engineer and Civil Engineering Practice Director at Exponent Failure Analysis Associates in Menlo Park, California, where he specializes in investigation and analysis of buildings damaged by extreme forces. Dr. Osteraas earned his Ph.D. and Masters Degrees in Structural Engineering from Stanford University and his B.S. in Civil Engineering from the University of Wisconsin. He has been active as a Structures Specialist in the USAR program with California Task Force 3 in Menlo Park since 1990. At the World Trade Center and at the Murrah Federal Building in Oklahoma City in 1995 he served on the Incident Support Team. His prior USAR deployments include the Northridge Earthquake in 1994 and Hurricane Iniki in 1992.