Long-standing doubts about more than 2,000 anchor rods and bolts on the new San Francisco-Oakland Bay Bridge were dismissed as unfounded in a technical report approved Friday.
The report by the California Department of Transportation and its consultants followed more than a year of study and testing of steel fasteners that hold up the suspension span. The research was ordered after 32 large anchor rods that secured essential seismic equipment on the eastern pier snapped under tension in March 2013, forcing a multimillion-dollar retrofit.
The final report, approved by the Toll Bridge Program Oversight Committee, judged all remaining parts as reliable against cracks or breaks – assuming protection against the marine environment and normal maintenance – for the projected 150-year service life of the bridge.
“The bolt report was accepted, and that seeks to close the discussion on all the bolt matters, except the tower foundation rods,” said Randy Rentschler, a spokesman for the oversight committee. He was referring to concerns about rods that secure the bridge tower to its foundation. Construction errors – the rods were not fully protected by grout, and most were exposed to water – are an issue under review by bridge officials.
Caltrans said it would correct the problem and issue a separate report on the tower rods. It said that the water was “rain or wash water,” not bay water, making serious corrosion less likely. “Further, the low tension level of these bolts does not make them susceptible to stress corrision (sic) cracking,” Caltrans’ report noted.
A recent 60-page report by Yun Chung, a retired metallurgist and engineer, cast doubt on Caltrans’ tests and conclusions and proposed replacing most of the rods and bolts. His report, endorsed by several other experts, said Caltrans’ draft report and its findings that the bridge is safe and durable were based on “unscientific” and “erroneous and misleading” evidence.
The approved Caltrans report did not address most of Chung’s technical criticisms. But it dismissed as unfounded his concerns about the margin for error in judging the strength and durability of the anchor rods and bolts.