How Calif.’s New Bay Bridge will Withstand Major Quakes
OAKLAND, Calif. (KGO) -- What was it like to be driving on the Bay Bridge when it collapsed on Oct. 17, 1989? ABC7 News spoke to a man who survived a once in a lifetime accident, 23 years ago.
And with 320 days to go before the new Bay Bridge opens, ABC7 News goes inside the bridge to bring you this construction update.
It's perhaps the most-enduring image of the 1989 Loma Prieta earthquake -- a driver's plunge into the gap created by a collapsed segment of the bay bridge.
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"The last thing I remember screaming is, 'We're going to die!'" said Bruce Stephan.
Stephan was also on the bridge, driving over the section that collapsed when the quake struck. He and his passenger both survived.
"I had been going 40, 50 mph before that and I was looking under the lower roadway. I was staring at the water on this weird angle. I had no idea why I was there, why I wasn't in the water...why I had lived," said Stephan.
"When Loma Prieta hit, it and took it beyond the four-inch throw that was designed in there, it sheared off all of the metal bolts," said Caltrans spokesman Bart Ney.
Ney explained to us why the old bridge failed and he took us inside the new eastern span for a rare view of exactly what components are built in to ensure there's no collapse in a future quake.
The new bridge has elements that are designed to take the brunt of a major earthquake, while leaving the rest of the structure, safe.
"The first thing we have are these giant bearings. They're like huge hockey pucks that take the first slamming of the energy of the earthquake. Right above us is a seismic joint. It almost looks like an accordion. It can bend and move omnidirectionally, in all different ways, so that cars driving over at that moment, the bridge doesn't separate, they can get through. There's a stainless steel cladding on the outside of this part of the beam, so it can slide in and out. We can accommodate six feet of movement at this location, three feet in either direction," said Ney.
"I'm not going to say that this bridge will collapse," said UC Berkeley structural engineer Hassan Astaneh. Astaneh doesn't predict a catastrophe, but has doubts about the seismic safety of the Caltrans' design. "There is no system designed like this in the world subject to earthquakes. No one knows how a bridge of this system, self-anchored, will perform during an actual earthquake."
Caltrans says the new span is built to withstand a 1,500 year earthquake that could be larger than both the Loma Prieta and the 1906 San Francisco earthquake.
Be sure to look at our Prepare NorCal page. It's got everything you need to know to be ready for the next big earthquake.
http://abclocal.go.com/kgo/story?section=news/local/east_bay&id=8851261
