Most people in the Bay Area know that. But they may not know their most important lifeline to the outside world is also one the weakest: the Bay Bridge connecting San Francisco to Oakland.
In 1989, the Loma Prieta earthquake severely damaged the Bay Bridge. At the time, California's leading engineers said it was a "powerful warning" that the bridge needed to be made earthquake safe. Their report was called "Competing Against Time."
Twenty years later, a new span that is a wonder of engineering is rising across San Francisco Bay. But it's still under construction, and there's a push to finish the job before the next big earthquake strikes.
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Web Extra: The End Of The Bay Bridge
The Golden Gate is the most recognized bridge in the world and, most people would say, San Francisco's most beautiful. But when you talk about California's economy, the Bay Bridge is the most important. With nearly 250,000 vehicles crossing it every workday, it's one of the busiest bridges in the world.
But, as California Department of Transportation (Caltrans) spokesman Bart Ney explains, here's the problem: "If a very large earthquake strikes now we're going to have trouble with that structure."
"That bridge goes in the water?" correspondent Byron Pitts asked.
"Portions of it, maybe," Ney replied.
Caltrans is the agency facing the challenge of making the Bay Bridge earthquake safe as quickly as possible.
"Where we're standing right now is probably lane two, heading westbound into San Francisco in 2013," Ney told Pitts, as they toured the construction project.
"You hope 2013," Pitts remarked.
"That's right," Ney said. "Now, that's what we're gunnin' for."
The Bay Bridge is actually two bridges. The western span reaches from San Francisco to Yerba Buena Island and is now stronger. In 2004, Caltrans finished replacing half a million rivets with bolts and added 17 million pounds of extra steel. This span is anchored to bedrock.
But the eastern span, stretching two miles to Oakland, is weaker. It sits precariously atop trunks of Douglas fir trees, which were driven into the mud more than 75 years ago. Despite concerns over its strength, it's still in use while a new bridge is built alongside.
Failure of the Bay Bridge is not just a fear, it's also a memory of what happened in 1989.
"That was the location where we had the failure during the Loma Prieta earthquake," Ney explained, pointing to the upper deck of the existing Bay Bridge. "Literally that top span collapsed onto the lower span."
At 5:04 p.m. on October 17, 1989, as ticket holders were entering the World Series, the ground started shaking. People panicked. On the Bay Bridge, stunned motorists took a video as a woman was killed when she drove off the fallen upper deck.
Sixty two other people died in the quake, most of them when a stretch of the double-decker Cypress Freeway in Oakland collapsed. In less than 15 seconds, the magnitude 6.9 Loma Prieta earthquake injured 3,700 people and caused $6 billion in property loss.
"And people living in the Bay Area said, 'Oh, yeah, we've lived here all our lives. We felt earthquakes, we can deal with earthquakes.' Then Loma Prieta occurred," geologist David Schwartz told Pitts.
Schwartz is on the Earthquake Hazards Team at the U.S. Geological Survey.
He says that as dangerous as Loma Prieta was, it was centered 60 miles away. "If people thought that was an earthquake, wait until the next one happens right here," Schwartz said.
When the Bay Area takes that direct hit from a major quake, many of its roads, bridges and airports will be devastated. People will die. Survivors will depend on a disaster route that connects to the outside world. The Bay Bridge will be the heart of it.
"The Bay Bridge is built to lifeline criteria," Ney explained. "This bridge, unlike almost every other bridge in the state is designed to handle a very large earthquake. And then put back immediately into service. For emergency services. And with a short period of time then be open to the public for the rebuilding effort that will happen in this region."
"The replacement structure that we are designing is really state of the art," Steve Heminger, executive director of the Metropolitan Transportation Commission, said.
Heminger holds the power and responsibility to get the bridge built and paid for. "I'll tell ya, if I'm lucky enough, I wanna be on that bridge when the big earthquake hits," he said.
"Sounds like a sales pitch almost," Pitts remarked.
"I'm not sellin' you on anything. I'm tellin' you that we have spent a lotta money and a lotta time makin' sure that this bridge is strong," he replied.