Many bridges are too shaky for extreme quakes
Since the Loma Prieta earthquake in 1989 and the Northridge quake in 1994, the state has been trying to seismically retrofitted bridges across California. Given the significant earthquake last week, I thought it would be a good time to provide an update.
The state owns more than 12,000 bridges. The California Department of Transportation says that in the last 20 years it has retrofit 2,189 of the 2,194 bridges that needed updates, many of which are on freeways and other major corridors.
The remaining five bridges are the eastern span of the San Francisco-Oakland Bay Bridge, the Ten Mile River Bridge on California 1 in Mendocino County, the High Street bridge on Interstate 880 in Oakland, the 5th Avenue bridge on I-880 in Oakland and the Schuyler Heim Bridge that connects Long Beach to Terminal Island.
The Schuyler Heim will eventually be replaced, said David Anderson, a Caltrans spokesman. Like the eastern span of the Bay Bridge, it’s less expensive to replace than repair.
In addition, 479 bridges owned by cities and counties need seismic upgrades and are eligible for funding from Proposition 1B, the $19.9-billion transportation bond approved by California voters in 2006.
Among these bridges that still need seismic updates are some noteworthy structures in the Southland. Eight cross the Los Angeles River in the city of Los Angeles, including the 6th Street Bridge and bridges on streets including Main Street, Glendale Boulevard, Vanowen Street and Tampa Avenue.
The Los Angeles Conservancy has expressed concerns about the river bridges in particular, saying that although the need for public safety must be met, fixes should also consider the bridges’ historical architecture.
Los Angeles County needs to fix more than 40 bridges, including the Foothill Boulevard bridge over the San Gabriel River in the San Gabriel Valley and an Imperial Highway bridge. In Riverside County, the Van Buren Boulevard bridge over the Santa Ana River needs an upgrade. So does the MacArthur Boulevard bridge at John Wayne Airport in Orange County.
Why am I listing these bridges? Because some of the same ones were mentioned by my colleague Sharon Bernstein when she wrote about bridges in need of seismic upgrades in March 2006.
The California Transportation Commission recently doled out about $21 million of the seismic funds, on top of $13 million previously allocated. Both the Vanowen and 6th Street bridges got money in that round of funding.
That allows cities and counties to seek Caltrans’ approval of their projects, which then allows the cities and counties to apply to the Federal Highway Administration for 88.5% of the cost of each project. That’s how the bureaucracy works.
One question you might have is what does “seismic upgrade” really mean? To put it simply, seismic upgrades are supposed to allow a bridge to withstand the maximum credible earthquake that could happen in any given area, Anderson said.
Of course, there are no guarantees. Intensive monitoring of earthquakes has revealed a lot of basic patterns about size, frequency and location, and scientists have mapped many of the region’s faults. But there are a lot of variables when it comes to how earthquakes release energy.
The bottom line is that no one can say with certainty what kind of damage the next big quake may cause.
“If you look at this whole planet of ours, the time window for which we have the [earthquake] data is so short in geological terms,” said Saiid Saiidi, a professor of civil engineering at the University of Nevada, Reno. “The science of seismology has progressed quite a bit in the last 30 years -- I may not know what the next big earthquake is going to be, but I can work on the structural side of it.”
When I dined with Los Angeles City Councilwoman Jan Perry last week, she said she was tiring of the delays in reopening the Angels Flight funicular on Bunker Hill. She said the nonprofit that oversees the railway should step aside and let someone else take over if it couldn’t get the line up and running.
It has been shut down since a 2001 accident, when faulty brake and mechanical systems caused a crash that killed one rider and injured seven others.
That sparked a response from John Welborne, president of Angels Flight Railway:
“Bricks and mortar help,” Welborne said. “Brickbats do not. The reason the historic Angels Flight Railway is being restored -- and safely -- is because of the many supporters whose positive contributions are getting us close to finishing this (big) job.”
Welborne said all Angels Flight work “is being financed through private community fundraising and support.”
For years, the foundation needed less than $100,000 annually to subsidize the railway’s 25-cent fare.
But after the crash, it had to raise nearly all of the $3.3-million cost.
Although there have been delays, work is now moving ahead.
“Our foundation’s directors share the frustration of our neighbors and visitors (and our local council member) who wish to see the railway back in operation,” Welborne said. “However, we said we would not reopen . . . until it is completely safe to do so.”