Failure™ Magazine

Suspended Animation

The collapse of the Tacoma Narrows Bridge.

Written by Jason Zasky   Filed under History, Science & Technology

Ketchum attributes many of the problems exhibited by today’s bridges to a lack of adequate pre-construction engineering—a combination of naivete among owners regarding design challenges and an unwillingness to provide the necessary financial resources. “We’re designing bridges with less and less engineering effort and less and less attention to what I consider the necessary aspects of whether or not it’s going to perform right. A suspension bridge with 500-foot tall towers, 10 million pounds of wire, 25 million pounds of steel plate, and 300,000 yards of concrete that has to be dangled from those towers is a little bit different than a ramp and an overpass,” he notes. The Rama IX bridge sounds like the perfect example: “Here we are 12 years after it was built doing engineering studies to make sure it isn’t tearing itself apart,” says Ketchum. “Maybe that’s our fault. As a professional group we’ve done a very bad job of convincing the public that there’s a need for risk management.”

Risk management may become a more significant issue as public officials call for ever-larger and more expensive bridges. To handle the increasing volume of automobile traffic, future structures will be bigger and longer than ever before. Currently, the Messina Straits bridge in Italy is being designed with two towers that will be a remarkable 3 km apart. But the mega-project of the future could be the three-tower Gibraltar Bridge, which would connect Spain and Morocco. If the project comes to fruition it most likely would require two 5 km spans flanked by two 2 km spans for a total of 14 km. “To build those it would require the world’s deepest water structures, the world’s tallest towers and longest span structures—all at the same time,” says Ketchum.

While it’s been sixty years since the Tacoma Narrows disaster, the fundamental issues remain the same. If public officials continue to push to envelope, squeeze pre-construction engineering budgets, and fail to anticipate the behavioral idiosyncrasies of cutting-edge design, it seems only a matter of time before there’s a high profile collapse. An old adage comes to mind: “You can pay me now or pay me later.”

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