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Princeton contingent helps assess WTC damage
Karin Dienst Princeton NJ -- There was no preparing for the devastation of the Sept. 11 attack on the World Trade Center, but a handful of Princeton faculty and students quickly mobilized to help structural engineers assess damage at the site and in neighboring areas.
"This effort continues with four SEAoNY teams of three structural engineers, each team from a firm, on 12-hour shifts," said Nordenson. "We alternate days so that makes for 16 teams, which are mostly from New York but also from Boston and Chicago. This will continue for weeks." Nordenson is leading the building evaluation work and coordinating those efforts with an engineering firm co-owned by Charles Thornton, visiting lecturer in civil and environmental engineering. The Thornton-Tomasetti Group Inc. has been hired by New York City to spearhead the engineering efforts at the World Trade Center site (see related story on page 6). Finding the most effective response to the urgent and drastic situation on Sept. 11 was the biggest hurdle facing the structural engineers and architects, as it was for everyone dealing with the emergency. "The greatest challenge was making judgments based on limited information with little or no documents in the first week," said Nordenson. This difficulty was compounded by the fact that the office of Guy Nordenson and Associates was just a block from ground zero. "It's been challenging to try to stay organized in the face of incredible pressures of time and necessity without the benefit of a consistent place to work from," said Brett Schneider, who works at Nordenson's firm. Schneider has a master's degree in civil engineering from Princeton and is also completing an architecture degree here. It was crucial to quickly but thoroughly assess the extent of damage to buildings in Lower Manhattan. To do this, Nordenson turned to a resource that provided a solid foundation from which to work. Earlier this year, he and fellow faculty member George Deodatis and Michael Tantala, a Ph.D. student in civil and environmental engineering, completed a study that determines the effects a medium-sized earthquake might have on Manhattan. This research project, undertaken for the Federal Emergency Management Agency (FEMA), created a database that describes the structure of every building in Manhattan. Although the stresses the buildings would have faced from an earthquake were quite different from the damage caused by the planes, the database was invaluable for providing information, already compiled and mapped, about hundreds of buildings in the area. The study also outlines procedures for assessing damage to these buildings. 400 buildings inspectedOn Sept. 15, Nordenson got the go-ahead from the mayor's Office for Emergency Management to proceed with the assessment. "We drew a map of the area between the Hudson River and William Street and Chambers and Rector streets and divided it into 15 sectors, excluding the part around the World Trade Center," said Nordenson. "We called around and arranged for 15 SEAoNY engineering teams, from some of the same firms that are working with the contractors, plus others, to do the inspections. These were to be in two stages: a rapid visual inspection from the street followed by a detailed evaluation of the damaged buildings." Each team was then given a packet of information, prepared by Tantala and Schneider (who also went on some of the early inspections), based on the earthquake forecast. The packets included maps and a checklist for each building. These were derived from the same procedure used for damage evaluations following the last California earthquakes. Armed with this information, the 15 engineering teams inspected about 400 buildings in two days. Information from the inspections was then entered into a database at Princeton by Tantala, Schneider and other students working around the clock. "Specifically, we were able to take the building information, identify pertinent structural and occupational characteristics and present this information visually to decision makers using geographic information systems," said Tantala. "Additionally, we were able to smoothly link this information with aerial photography and other data recorded by military jets that flew over the area daily. This aided engineers inspecting the buildings by allowing them to identify roof damage or debris that might cause added distress on these buildings." On Sept. 19, Nordenson and his colleagues presented a list of damaged buildings and the extent of the damage to the New York City Department of Buildings and the NYC Department of Design and Construction. About 30 buildings required a closer look, and new teams were fielded to go through a more detailed checklist prepared by the Princeton students. By the end of that week, a full report rating the structural damage to 415 buildings was drawn up using the information gathered by all the teams: 384 buildings are sound, with no restriction on occupancy; 18 have moderate damage but can be re-occupied following repairs; nine have major damage and are closed to all but emergency personnel; and four are partially collapsed, likely to be demolished. "In an emergency situation like this where every minute counts, having our research at Princeton readily available and in a form that was of use to the response effort enabled the city to more quickly assess the impact of this disaster on the surrounding structures," said Tantala. "The faster you can say which buildings are safe and which aren't," he continued, "then the sooner the response effort can focus its limited time and energy on the trouble spots for repair and the sooner people can be permitted into the restricted parts of that area and get back to work. Some of the people in emergency management services have speculated that Princeton's effort has saved them at least a week or two with the structural assessments." Tantala pointed out that the information will also "serve to further document the tragedy and aid FEMA in assessing the financial compensation for people in the area." The constant activity in getting the job done for Nordenson, Schneider, Tantala and other Princeton volunteers does not diminish their emotional involvement in responding to the World Trade Center catastrophe. On the one hand, Nordenson said, it was rewarding to be able to offer his skills in a time of need. "The experience is inspiring and unforgettable," said Nordenson, emphasizing the "compassion and courage all around." On the other hand, being so close to the tragedy has been devastating for the volunteers. "I've been to the site several times now and was a block away on Sept. 11," said Schneider. "I'm still unable to connect the World Trade Center I knew so well to the events of that day and now to the rubble that remains. It feels like three separate places." Tantala is constantly reminded of the people he knew who worked in the buildings. To date, 11 Princeton alumni have been confirmed as victims of the terrorist attacks and several others remain missing. "As I did this work and thought about the events, I was in shock about what had happened," said Tantala. "Many people died. Many of my friends were there. I was just eager to be able to help in any small way with this effort even with just my numbers and words." |
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