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Building a bridge that's ready for the big one

Construction of the new San Francisco-Oakland Bay Bridge is incorporating seismic innovations that engineers hope will help it stand up to the next big earthquake.

During the Loma Prieta earthquake on October 17, 1989, which measured 7.1 on the Richter scale, the San Francisco-Oakland Bay Bridge nearly collapsed. Just one or two seconds more of shaking along the San Andreas fault zone, says Caltrans' Bart Ney, and the whole bridge would have come down.

Today, the seismic innovations being incorporated into the construction of the new San Francisco-Oakland Bay Bridge are far more advanced. The construction is a race against the clock, and engineers say the new bridge, once built, will be secure enough to survive a "massive level earthquake--the largest you would see in 1,500 years."

Some of these innovations have been developed by Caltrans and are being used in this kind of construction for the first time; they should allow the bridge to bend and contort along with the massive energy emitted by a high-level earthquake. Independent sections, linked with movable joints and flexible surfaces, will keep the bridge safe and easily repairable following a major seismic event.

Last week, CNET photographer James Martin went along with Caltrans inside the bridge, getting an up-close look at some of the technologies being designed to keep the Bay Area safe.