Diane Hartley Found Citicorp's Flaw

In 1978, a woman named Diane Hartley was completing her undergraduate architecture thesis when she discovered that New York's 59-story Citicorp Center could topple if powerful winds struck its corners. After Hartley raised the problem with a junior staffer, chief structural engineer William LeMessurier checked her calculations and found that a collapse-level storm could strike every 55 years, or every 16 years if a blackout disabled the building's 400-ton stabilizer. His team secretly welded the skyscraper's joints at night while the NYPD prepared an evacuation plan covering a 10-block radius and 2,500 Red Cross volunteers stood ready. The public did not learn about the crisis until 1995.

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