The report by Berkeley Research Company metallurgical and materials engineer Lisa Thomas and retired materials engineer Yun Chung focuses on the anchor rods for the main cable and the tower base of the new East Span of the San Francisco-Oakland Bay Bridge.
In an earlier report published in October, Chung and Thomas had informed the California Department of Transportation, Caltrans, and the Toll Bridge Program Oversight Committee of what they saw as "some 200 errors and technically questionable or erroneous statements" in the final report into the anchor rod failures that were discovered in March.
Remedial measures were identified by the bridge's owners to address problems in the area where the fractures occured as well as concerns about other anchor rods. A temporary fix allowed the bridge to open to traffic in September ahead of completion of the permanent solution.
The latest report from Chung and Thomas says that the anchor rods for the parallel wire strand main cable and the tower base are fracture-critical; their failures could bring down the entire SAS Bridge. The authors say that TBPOC and Caltrans are not cognisant of metallurgical problems unique to these anchor rods and that the remedial resolutions are unsatisfactory. Test protocols must be significantly augmented to provide valid assurance that these anchor rods will not fail due to hydrogen embrittlement during service, they say.
