Bay Bridge review panel says new span's foundation is safe
03/24/2012 12:00 AM
04/11/2012 8:47 PM
An expert engineering panel has concluded that the foundation of the new eastern span of the Bay Bridge is safe and sound, according to its report released Friday.
The expert review was prompted by a Bee investigation last fall showing that a state technician had fabricated radiation-based integrity tests on other structures, and failed to ensure accuracy when examining the foundation piles of the new span's main tower. Caltrans fired the technician and his supervisor after The Bee's report.
Writing for the four-member Toll Bridge Seismic Safety Peer Review Panel, chairman Joseph Nicoletti said the foundation piles for the main tower were "designed, constructed, and tested in a way that meets or exceeds the state-of-practice and will result in a safe and reliable performance of the bridge."
California Department of Transportation acting Director Malcolm Dougherty said the findings reflected Caltrans' own examination of the issue.
"Evidence shows the Bay Bridge tower foundations are safe and no falsifications have taken place regarding testing data," Dougherty said.
Officials plan to open the new $6.5 billion eastern span by Labor Day next year.
The panel began its work in December, and relied on a report on the bridge piles prepared by Earth Mechanics Inc. "under the direction of Toll Bridge Program staff." It also built demonstration piles to conduct tests to simulate some of the conditions of the bridge piles. Details of those reports were not released as of Friday evening.
The Bee story last fall also quoted pile design experts who described concerns about whether the piles were built in ways that might impede the flow of concrete within them, leading to defects.
The demonstration piles "confirmed the desired flow characteristics of the concrete," Nicoletti said, and tests of those piles were highly favorable, suggesting that the actual bridge piles are similarly reliable.
Nicoletti reported that Caltrans and Federal Highway Administration engineers each examined Caltrans test data to check for possible fabrications and found none. Instead, Nicoletti wrote, the radiation tests "showed good results." Those technical evaluations of the test data also have not been released.
Additional acoustic-wave tests of the foundation concrete also showed good results, Nicoletti wrote.
With regard to overall concerns about the structure's safety, he said, "we find that the foundation design contains a significant amount of redundancy and has a large margin of safety against unforeseen events."
The panel concluded that "no remedial testing, research, or other investigation or physical reconstruction is necessary to ensure full compliance with the design intent."
The panel, appointed by Caltrans, includes Nicoletti, a structural engineer; Izzat M. Idriss, a geotechnical engineer and professor emeritus at UC Davis; John Fisher, a structural engineer and professor emeritus at Lehigh University; and Frieder Seible, dean of the UC San Diego Jacobs School of Engineering.
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