The San Francisco Oakland Bay Bridge opened in 1936. Today it carries nearly 250,000 cars a day.
This is a view of the Eastern Span of the bridge opened in 2013. The old span is being disassembled.
A section collapsed on the Eastern Span of the bridge during the 1989 Loma Prieta Earthquake and the eastern portion of the bridge opened nearly two years ago at a cost of 6.5 billion dollars.
While the western section of the bridge was retrofitted . The entire eastern section had to be replaced.
Before the bridge opened, we learned Caltrans allowed a number of giant steel bolts to be installed which later snapped after they were tightened. Bolts on the Bay Bridge were allowed to be installed despite a lack of quality-assurance testing.
Of the span’s 96 bolts, which range in length from 9 to 17 feet, 32 snapped when stress meant to simulate the lateral motion of a large earthquake was introduced.
This isn’t the first time
The Carquinez Suspension Bridge opened in 2003. Caltrans avoided “near disaster” when the agency discovered at the Carquinez Bridge construction site that 250,000 critical bolts had been made to the “wrong size and they all had to be rejected and remade,” according to the report written by an independent investigator.
This story was never revealed to the public,” according to the report prepared for the California State Senate Transportation & Housing Committee
The bolts for both bridges were made by the Chinese company of Shanghai Zhenhua Heavy Industry Co., also known as ZPMC. After hiring the same firm for the Bay Bridge, Caltrans implemented a safety protocol for the Bay Bridge following this incident on the Carquinez Bridge.
Last week we learned,one of the steel rods anchoring the tower of the new Bay Bridge eastern span has failed a key integrity test, suggesting it became corroded and broke during years when it was soaking in water.
Photo: Paul Chinn / Paul Chinn / The Chronicle
The test result raises the possibility that hundreds of other rods that have been steeped in water in the bridge’s foundation in recent years are in danger of cracking, which could reduce the stability of the 525-foot-tall tower in a major earthquake.
Rust and corrosion from a puddle of water are seen next to bolts in one of the hollow steel box girders that make up the roadway of the Eastern span of the Bay Bridge in Oakland, CA Monday, February 10, 2014.
State officials remained optimistic Thursday that corrosion was not to blame, and stressed that Caltrans isn’t certain of the rod’s condition because workers have not removed the 25-foot-long fastener from its sleeve.
The underside of the SAS bridge deck of the new eastern Bay Bridge span is seen in San Francisco, Calif. on Thursday, Feb. 6, 2014. Engineers are monitoring areas where small amounts of water is seeping into the structure, a situation which is not uncommon, according to spokesman Andrew Gordon.
This is the latest bad news for Caltrans, which was rocked last week when tests on water found in three rod sleeves turned up elevated chloride levels — possible evidence of saltwater intrusion into the foundation. The bridge project’s oversight committee approved $400,000 to test more rod sleeves to see how widespread the problem is.
The chloride levels were about half what is normally found in salt water, Caltrans says. But they also were 50 times higher than what Caltrans found in water removed from rod sleeves last fall, when crews discovered that the bridge’s lead contractor had done an incomplete grouting and sealing job.
Experts say that if the rod that Caltrans is removing this week is indeed fractured, many of the other rods could be in jeopardy. There is precedent for that: Thirty-two similar steel rods failed on the bridge’s seismic-stabilizer structures in 2013 after they were exposed to rainwater for several years, forcing Caltrans to engineer a workaround that cost $45 million.
Despite its issues, the bridge is safe. The question is. Can it withstand a large earthquake?