Years After Loma Prieta, Many Columns Supporting Bay Area Roads Still Need Retrofitting for Quake Safety

25 years after the Loma Prieta earthquake in 1989, the Investigative Unit has discovered many columns still need to be retrofitted for safety. And some that have already been retrofitted need to be looked at again.

After the 6.9-magnitude earthquake hit, it took just six seconds for the columns that supported the Cypress Freeway in Oakland to buckle. The failure eventually forced the upper deck of the freeway to collapse onto the roadway below. 35 cars and trucks were crushed in the rumble.

“It was a horrific scene, surreal,” Dr. Jim Betts told the Investigative Unit. He sat down with The Investigative Unit at UCSF Benioff Children’s Hospital Oakland, where he serves as a staff surgeon and director of trauma services. When Loma Prieta hit, Betts was one of the first doctors to rush to the Cypress Freeway and climb into the chaos.

“The whole situation was so unnatural for those of us who hadn’t actually been in an earthquake of that magnitude,” said Betts. He performed emergency surgery on a six year-old boy beneath the tons of concrete and steel. Betts was able to save the boy’s life, but 42 others died. “I think you have to have a very sobering reality that something like this can happen again,” reflected Betts.

Archive footage of the Loma Prieta Earthquake from California Highway Patrol

The Investigative Unit has discovered that when the next powerful earthquake happens, some columns may not be stable enough to withstand intense shaking. Some columns supporting bridges, ramps, and railways in the Bay Area have yet to be retrofitted.

“The ones that have not been retrofitted would not fair very well,” said Professor Anne Kiremidjian of the Civil and Environmental Engineering Department at Stanford University. Kiremidjian, who has studied the aftermaths of dozens of quakes since coming to Stanford in 1972, said the old, non-retrofitted columns will sustain the most damage when the next big event occur. Kiremidjian said records and geological tracking shows the Hayward Fault Zone is due for an earthquake.

The Investigative Unit has uncovered 250 columns on a four and a half mile stretch from the Oakland-Alameda County Coliseum to Lake Merritt still needs to be retrofitted. The railway was built more than 40 years ago and it happens to sit about three miles from the Hayward Fault Zone.

Tom Horton is the Group Manager of Bay Area Rapid Transit’s (Bart) Earthquake Safety Program. “I can’t tell you today that we have a 100% guarantee that the system will withstand all earthquakes; no one can tell you that and that’s just the place we live in,” explained Horton. His team has raced to retrofit 1702 columns along 70 miles of track. Bart expects to finish the last stretch of system from the Oakland-Alameda County Coliseum to Lake Merritt in 2019.

The reason for the delay? “We had some issues with funding. In fact, we have some federal funding that needs to be allocated,” explained Horton.

In order to retrofit the columns, crews must widen the base beneath each one; then create a system of re-bar that circles the columns like a spring and add another layer of cement. Other columns will have a metal casing placed around the columns. Workers are also making cement crossbeams larger and stronger beneath the train tracks.

An example of how Bart retrofits some of its columns for earthquake safety.

“Bart uses the same system of ductility, toughness, flexibility that what we know as the experts is the best way to fight the earthquakes,” said Tom Ostrom, who is the Chief of Caltrans' Earthquake Engineering Office. Since Loma Prieta, he says Caltrans has spent $14 billion retrofitting more than 2,000 bridges in California.

But new earthquake data from the US Geological Survey may force the agency to go back and retrofit some of the bridges and columns again, which were first stabilized in the 1990s. The locations of the bridges and columns–if any–won’t be made public until this summer.

When asked if Ostrom would feel comfortable driving on the bridges that may need to be retrofitted again, he stated “Yes, absolutely because we know that we've done a great job in increasing their safety.”

Ewa Bauer, Chief Engineer of the Golden Gate Bridge Highway and Transportation District explains how the Golden Gate Bridge earthquake retrofit works

But Caltrans doesn’t control all the bridges and columns. The Investigative Unit analyzed the National Bridge Inventory (NBI) database, which is compiled by the Federal Highway Administration. By comparing the NBI database with data provided by Caltrans, NBC Bay Area discovered 26 bridges throughout the Bay Area owned by local authorities that still need to be retrofitted, including eight crucial bridges and ramps that connect Yerba Buena Island to the Bay Bridge. Those structures are owned by U.S. Navy. It is transferring the ownership of the bridges and ramps to the City of San Francisco, which is expected before the end of March. The $66 million project won’t be completed until 2019.

San Francisco County Transportation Authority
The aerial structures on Yerba Buena are critical to connecting to the freeways and the rest of the city. These structures are managed by SF County, not the state.

The Unit also found that the Niles Boulevard Bridge, which is owned by the City of Fremont, needs to be stabilized to withstand a large earthquake. In the meantime, an average of 15,000 vehicles cross it every day. The bridge is directly over a Bart track, but Bart has no jurisdiction over the bridge. The City of Fremont plans to replace it by the summer of 2016.

While the Bay Area waits for another powerful earthquake to shake the region, Dr. Jim Betts fears that those older structures might hinder saving lives: “You’re limited by either what resources you can bring in or getting people out of that kind of dangerous area - wherever it is.”

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