OAKLAND, Calif. (KTVU) - In the aftermath of the Loma Prieta earthquake, the eastern span of the Bay Bridge, was designed to be seismically strong enough to withstand the largest potential earthquake in 1,500 years.
In October 1989, the 6.9 magnitude Loma Prieta earthquake caused major damage to some of the Bay Area’s most traveled roads and bridges. The Cypress Freeway in West Oakland was leveled, killing 42 and trapping many others.
One of them was a 6-year-old boy that Dr. James Betts will never forget. Betts was working at Children’s Hospital Oakland at the time and recalls the hospital preparing for mass casualties, but that didn’t happen. He made a call to a fire station and was told there were people trapped under the Cypress Freeway. Betts left the hospital to join first responders and said he would not leave the scene until they helped free the boy.
“His legs were trapped under the front seats of the vehicle,” Betts recalled. “His right leg was crushed to his knee and his left leg was trapped. I knew we would have to do an amputation of his right leg.”
Betts said two people died in the front seat of the car and one of the bodies was crushing the boy. It made the rescue even more difficult.
“It was an extraordinary event,” Betts said. “It wasn’t anything that any of us planned on doing.”
A total of 63 people died and more than 3,000 were injured across the Bay Area. Part of the Bay Bridge fell too. It was a wakeup call for Caltrans.
“After Loma Prieta, we had to come up with new criteria to build bridges so we could get goods and services into an area that's significantly damaged,” Caltrans Spokesman Bart Ney said. “We did a lot of studies. We invented new technologies so the bridge would move in a large scale earthquake.”
Enter the new eastern span of the Bay Bridge. The self-anchored suspension bridge, which cost $6.5 billion to build and completed in 2013, was engineered with new technology that isolates damage and allows the tower to stay standing during an earthquake.
“This is the strongest earthquake bridge ever built,” Ney said.
Caltrans gave KTVU an inside look at how the Bay Bridge is seismically resilient. Our crew was taken below the freeway deck, down a narrow hallway, and through small openings in the steel to get to a transition point where hinge pipe beams are located. Hinge pipe beams are designed to bend and deform in an earthquake.
“When the original Bay Bridge failed in 1989, there was only about 4 inches of movement, with these we can accommodate six feet of movement,” Ney said.
The hinge pipe beams can be cut out and replaced after they’re damaged. That’s the same idea for the shear link beams that are inside the tower of the bridge.
“Those beams bend and deform, keeping the tower strong and we can come in and replace later,” he added.
Our tour of the bridge continued on the tower where we climbed numerous ladders to get roughly 300 feet above the water. The tower stands at 525 feet high. The elevator happened to be out on the day of our visit.
Caltrans showed our crew what the shear link beams look like, steel rectangular beams that are hidden under the façade of the white tower. The beams are designed to absorb the shock and energy of an earthquake. The four legs of the tower bridge that the beams are connected to, operate independently and should not be damaged in an earthquake.
“From an earthquake standpoint, there's nothing more seismically resilient,” Ney said.
The Bay Bridge’s engineering will one day be put to the test. It sits right between the San Andreas fault and Hayward fault. Caltrans insists any past issues with the bridge are resolved. Rusted tendons have been replaced and anchor rods are in good order, according to Ney.
“In the Bay Area, we've just gone through a major retrofit period where we've replaced and retrofitted all of our large scale bridges so in the event of a large scale earthquake, which we know will come, we're ready,” he said.
But roads are in rough shape. Caltrans is working on more than 500 projects throughout the state, using money from the state gas tax to get them fixed.
“We know our infrastructure needs a lot of work roads, bridges, overpasses… I think about this every day,” Dr. Betts said.
Betts hasn’t spoken to the boy he helped save years ago. He only knows that boy is now a man in his 30’s and is doing well. Since Loma Prieta, Betts became a volunteer firefighter and first responder. He knows it’s not a matter of it, but when, the next big one will hit.
“We are in better shape than we were back then and we're constantly getting better,” he said.