San Francisco

Bay Bridge Lead Designer Fears Leaks are Damaging Main Cable

The lead designer of the Bay Bridge has warned Caltrans that the cable that holds up the new bridge's eastern span is vulnerable to corrosion because of rainwater leaking into its anchorages.

Bridge officials have been preoccupied with the possibility that rods at the base of the span's tower could be corroded by water but lead designer Marwan Nader of the T.Y. Lin International design firm in San Francisco said the bigger concern is the cable — specifically, the twin steel boxes where the cable is anchored inside the span's deck, according to the San Francisco Chronicle.

On the span, the cable is protected from the elements by a steel jacket. But in the anchorages on either side of the eastern end, the strands fan out and are exposed, and if water gets to them, they can corrode and fail.

The corrosion danger is very real on the $6.4 billion project, Nader told a Caltrans-convened peer review panel in July. According to minutes of the meeting, released only recently, Caltrans officials acknowledged that rainwater has been flowing into the two anchorages because of design problems with the guardrail system.

"He noted that the cable structure is the most important element in this bridge and needs to be protected," the minutes say. Although each anchorage has a dehumidifier, that system can't handle water flooding in from rain, Nader said.

"The dehumidification is not effective if rainwater is allowed to seep into the east anchorage," Nader told the Caltrans panel, according to the meeting minutes.

Nader did not respond to requests for comment.

Caltrans has yet to say how it plans to deal with the leaks. Brian Maroney, the bridge project's chief engineer, has said the idea is to wait for a storm that lasts several days and exposes all the spots where water is getting into the deck and anchorages.

"What's going on right now is not acceptable to us, and we're going to fix it," Maroney said in March. He said at the time that he had only recently learned that a key element of the bridge drainage system had been dropped, contributing to the leaks.

Copyright AP - Associated Press
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