Why Doesn't L.A. Have More Supertall Skyscrapers?

When completed in 2017, L.A.'s Wilshire Grand Center will be the tallest skyscraper west of the Mississippi. At 1,099 feet tall, the $1 billion, 73-story hotel and office building will just edge out L.A.'s current skyscraper king, the 1,018-foot U.S. Bank Tower built in 1989. L.A.'s tallest spires will be around the same height as as the Chrysler Building, built in 1930. By contrast, New York has seven towers that rise more than 1,000 feet (and more in the works). Which prompts the question: Why isn't L.A. taller?

Lagging market demand and a history of sprawling development are only part of the story. Two hazards native to the land, high winds and earthquakes, are deeply inhospitable to supertall skyscrapers. Which makes the design of an L.A. tower something approaching a high-wire act.

The Los Angeles Times has been following the construction of the Wilshire Grand and contends that it is "arguably the most complicated high-rise ever built."

The San Andreas fault passes 35 miles northeast of Los Angeles, and the city is at risk for major earthquakes. Because of the Santa Ana winds that blow down from the Mohave desert and the Great Basin, L.A. also gets gale-force winds on a regular basis. "Calculated to sway during powerful Santa Anas and absorb ground movement during the most severe earthquakes, it is wedded aesthetically and technically to the unique footprint of the region," the Times writes of the building. While other skyscrapers are often anchored by steel or concrete columns rooted in bedrock, the Wilshire Grand is built on a massive concrete slab. Reporter Thomas Curwen writes:

Its specifications were drawn up by engineers, who after calculating the height and weight of the tower and the forces associated with earthquakes and windstorms, determined that it needed to contain 21,200 cubic yards of concrete and 7.1 million pounds of reinforcing steel.

By some calculations, those ingredients are enough to build an entire 10-story office building.

Such a foundation required 2,120 truckloads of concrete, poured continuously into an 18-foot-deep hole two-thirds the size of a football field. The process, described afterward by a thermodynamics expert as "a logistical nightmare," earned a Guinness World Record for the longest continuous concrete pour, lasting more than 18 hours. While huge underground foundations are not unheard of in skyscraper design (the new One World Trade Center in New York is 1,776 feet tall and features concrete footings 200 feet underground), L.A.'s unique geography certainly makes for a complicated job.

[Image: Renderings via Wilshire Grand Center]

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Why Doesn't L.A. Have More Supertall Skyscrapers?