Transportation officials still have no firm estimate of when the bridge will reopen.
"Caltrans is doing everything it can to return the bridge back to a safe state," Bart Ney, a spokesman for the state transportation department said at a news conference Thursday morning.
The bridge closure made for a rough commute, with heavy traffic and crowded trains. Other bridges that provide access to San Francisco were especially congested, as some of the estimated 280,000 commuters who use the Bay Bridge each day looked for alternate routes.
Three cars were damaged and one motorist had minor injuries when the chunk of metal fell onto westbound lanes during Tuesday evening's rush-hour commute.
The pieces that failed were parts of major repairs done last month after state inspectors discovered a crack in an "eyebar," an important structural beam. The rods that broke were holding a saddle-like cap that had been installed to strengthen the cracked eyebar.
Ney said Thursday the crack in the eyebar has not gotten any bigger as a result of Tuesday's failure.
Officials with the California Department of Transportation have attributed the incident to vibrations and grinding on a metal tie rod, causing it to snap. They plan to make enhancements to address that issue.
Officials say strong winds likely played a role in the failure, heightening concerns by some experts about the integrity of the repair and the bridge's safety in an earthquake. Scientists in 2008 said there is a 63 percent probability of a quake similar to the 6.9-magnitude 1989 temblor in the Bay area over the next 30 years.
The earthquake 20 years ago caused a 50-foot section of the bridge's upper deck to collapse onto the deck below, causing another section to give way.
It took state officials until 1997 to decide it would be cheaper over the long run to build a new span than retrofit the existing one.
The main contractor on the repairs, C.C. Meyers, Inc., stood by the work, but deferred to Caltrans to determine why the pieces failed, spokeswoman Beth Ruyak said.
Meanwhile, the Federal Highway Administration sent engineers on Wednesday to help Caltrans investigate. The federal agency said it had not inspected the Labor Day weekend repairs made to the heavily used span, instead relying on state inspection reports to ensure safety guidelines were met.
Copyright 2009 The Associated Press.
