The roster of collapsed or partially destroyed buildings include: the south tower, called Two WTC, which came down at 10:05 a.m. on September 11; the north tower, called One WTC, which crashed down at 10:28 a.m.; and the 47-story Seven WTC, which collapsed at 5:20 p.m. Later, the Marriott Hotel came down and burned. The Four, Five, and Six WTC structures remain standing but are essentially ruined.
As of September 18, most of the 50 or so buildings closest to the towers have exterior damage, but only about 10 suffered structural damage. According to Daniel Cuoco, a managing principal of LZA-Thornton Tomasetti, the New York City engineer leading the structural engineering operations including damage assessment surveys for the New York City Dept. of Design and Construction, no more buildings outside the WTC have collapsed.
A recent structural damage assessment of 406 buildings several blocks in each direction outside the immediate impact area found 382 buildings in good condition, 20 with some damage, and five unsafe. No foundations are in danger of collapse, even within the WTC, notes George Tamaro, an engineer with Mueser Rutledge Consulting Engineers, which is leading the city’s foundation engineering operation.
Photo courtesy of FEMA.