Probe questions Bay Bridge concrete
Just what you needed, a bit of food for thought as you look forward to traversing the brand new eastern span of the Bay Bridge.
An investigation by the Sac Bee has revealed multiple potential safety concerns over the concrete used in the span’s signature tower.
The Bee, frankly, has kicked the ass of Bay Area media outlets in staying on top of issues with the brand-new bridge’s construction. This time, they looked at records provided by Caltrans to reassure the public after a previous story by the paper had revealed that a Caltrans worker had cut corners on required tests of the foundation and other bridge structures.
According to the paper, the records revealed that tests to determine the integrity of a 19-foot section of concrete on the bridge had not hardened prior to being tested. The joint venture that built the bridge’s foundation, Kiewit-FCI-Manson, failed to provide test results until after the the Bee’s original investigation.
Experts told the Bee the issue and others discovered with the bridge could expose issues regarding its structural integrity.
In addition to questionable concrete in the underground piles, numerous other problems with the bridge and reported data were found. Among them were problems in at least two of the bridge’s key piles, No. 3 and No. 8.
Pile No. 3 contained the 19-foot of concrete that had not hardened prior to being tested. It was not retested.
Pile No. 8 either did not receive sonic tests at all, or the builders could not locate the test results. Inspections during construction indicate abnormalities in pile No. 8.
Caltrans’ assurances that the bridge is safe are contradicted by agency documents. For example, panelists who reviewed sonic tests said that Pile No. 3 was safe, yet their work relied heavily on full-scale mock-ups. Experts told the Bee that comparing the full-scale bridge to scaled-down mock-ups was invalid.
Caltrans spokesman Tamie McGowen told the Bee:
“We are confident in the structural integrity of the main tower foundation and that the bridge will perform as designed to handle an extreme earthquake.”
A university professor who declined to be identified was skeptical about Caltrans conclusion:
“A job of this magnitude? Close to 20 feet of material near the top of the shaft showing anomalous readings? At least it requires some discussion.”