The phone call that may have saved a building from falling onto New York City

Mike Krumboltz, Yahoo News
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Walk around Manhattan and you'll see dozens, if not hundreds, of feats of engineering sure to leave even the most cynical urbanite gobsmacked.

One of the most amazing buildings in the Big Apple is located at 601 Lexington Avenue. The structure's spectacular design is outdone only by the story of how a student discovered it wasn't as safe as the experts believed.

The story has been known for years, but a recent post in inspired a new surge of interest.

The 59-story tower, at one time the world's seventh tallest building, was built on humongous stilts in order to accommodate a nearby church. To work around the church, the architect and engineer placed the stilts in the center of the building's sides, not at the corners.

It was a bold move and made possible via a chevron structure, a series of eight rows of giant steel V's that acted as the building's skeleton and overall decreased the weight of the building. To compensate for the building's lightweight stance, chief engineer William LeMessurier had to attach a giant 400-ton mass damper atop the building that would stabilize it during high winds.

Things went well until one day, in June of 1978, about a year after the building opened, when LeMessurier got a phone call from an undergraduate student named Diane Hartley. She told one of his staffers that the building could suffer a catastrophe should it face strong winds to its corners (called quartering winds).

Via Slate:

Normally, buildings are strongest at their corners, and it’s the perpendicular winds (winds that strike the building at its faces) that cause the greatest strain. But this was not a normal building.

LeMessurier did some calculations and discovered that Hartley was right. If, during a storm, the electricity went out, the giant 400-ton damper would potentially not work properly. If that didn't work properly and a strong wind hit the building on one of its corners, the building could topple and cause a domino effect in midtown Manhattan.

And it wasn't a one-in-a-billion type chance. According to Slate's summary of the amazing story, "LeMessurier calculated that a storm powerful enough to take out the building hits New York every 16 years." So, basically, each year, there was a 1-in-16 chance that a 59-story tower in the middle of Manhattan could collapse and reduce city blocks to rubble.

Thankfully, LeMessurier didn't sit on the potentially humiliating information. He worked with CitiBank (the building's owner), the New York Police Department, and the Office of Emergency Management to construct an evacuation plan that covered a 10-block radius. Repairs were also ordered.

All of this was kept secret from residents. Workers conducted repairs to the building after businesses shut down for the night.

Repairs were only halfway done when in August 1978, Hurricane Ella came storming toward New York. The plan to evacuate every building in the 10-block radius was prepared. Fortunately, it was not necessary -- Ella didn't hit land.

A few months later, the repairs were completed and the story went untold until 1995 when the New Yorker ran a story about the previously unknown crisis.

Amazingly, Hartley had no idea that her phone call had such an impact on New Yorkers. Slate reports that she only learned of the actions taken by LeMessurier after she saw the BBC documentary about the crisis (embeded above), which aired in 1996.

Follow Mike Krumboltz on Twitter (@mikekrumboltz).