A Sacramento Bee investigation has raised questions about the structural integrity of the San Francisco-Oakland Bay Bridge's foundation and its ability to withstand a major earthquake.
The May 26 newspaper report says that Kiewit-FCI-Manson, the joint venture that is constructing the bridge, failed to disclose that a 19-ft section of concrete in an eastern-span tower foundation had not hardened before it was tested. The Bee found descriptions of the section in records provided by the California Dept. of Transportation to the public last fall.
This is the latest concern for the new $6.3-billion Bay Bridge, the largest public-works project in the state's history. It is scheduled to open by Labor Day 2013.
Malcolm Dougherty, director of Caltrans, told ENR in an exclusive phone interview that there is no lack of due diligence. "We have already done a peer-review panel with national experts who reviewed all construction records and a mock-up of the actual foundation," he says. A Kiewit spokesman agrees, saying, "We stand firmly behind the safety and quality of the work KFM has done."
Caltrans received complete data from foundation testing, concrete cylinder strength tests, slump tests and gamma-gamma radiation tests conducted in 2007, Dougherty explains. The agency tested six piles but not Pile 3 or Pile 8, places where the Bee notes structural concerns.
A subcontractor for Kiewit ran sonic tests on Pile 3 for its own quality control but did not run any tests on Pile 8. "The sonic test was optional, and we didn't ask for it for either pile," Dougherty says.
"We did gamma-gamma testing after they did sonic testing, and our test came back favorable, so we never needed sonic testing to assess Pile 3," he says.
This pile cured to a higher strength than specified, based on cylinder strength tests, he says. The Toll Bridge Program Oversight Committee will decide if any additional steps will be taken, Dougherty adds.
"We have full confidence the bridge will perform as designed," he says. "It has a triple safety factor, in addition to strict oversight of construction and oversight by an expert peer-review panel."