Caltrans is now in the process of inspecting all of the bolts on the eastern span of the San Francisco-Oakland Bay Bridge that were manufactured by Dyson Corp.
Last week, 96 of the rods fabricated by the supplier snapped after post-tensioning. Dyson Corp. has made or supplied a variety of bolts, fasteners and other items that have been used in the construction of the signature span.
Caltrans said earlier tests performed on some of the galvanized bolts had raised some concerns about their ability to stretch during an earthquake, but were approved for use anyway. The agency did not test the bolts for the presence of hydrogen in the steel, which many believe is why the bolts broke apart. Officials assumed the threat was eliminated during the manufacturing and/or galvanizing process.
Caltrans Director Malcolm Dougherty has ordered a complete forensic analysis on the bolt failure, and also wants an audit and reinspection of all parts manufactured by Dyson that are on the bridge.
It will cost approximately $1 million to fix the broken bolts, and Dougherty said engineers needed to vouch for the safety of the span before motorists travel over the crossing.
