With only 159 days to go before the new span is scheduled to open, the question now is whether the defective parts can be replaced in time.
Caltrans says the root issue is hydrogen that apparently slipped into the steel rods. Despite some routine testing, the problem didn't come to light until earlier this month after the rods were installed and tightened.
The busted bolts are the latest problem to affect the new bridge. First, microscopic cracks were found on the decks made in China. Then, there were problems with the welds on the skyways. Now a bad batch of giant bolts or rods will need to be either reinforced or replaced.
"This bridge is not going to open if it is not safe. When it opens, it will be safe," said Caltrans project manager Tony Anziano.
The issue came to light a few weeks ago when about 30 metal rods were tightened with nuts at both ends and they broke.
"In an issue like this where they have bolts that have some type of issue with them, they've got a third-party review group -- some of the best engineers in the world -- that actually help them determine what the solution will be and how they'll implement it," said bridge construction consultant Bart Ney.
The faulty bolt systems are beneath the roadway decks. There are 288 of them in all. So far, 96 of the 9 to 24 foot rods have been tightened, and about one-third have failed.
"These things don't hold the bridge up, but they do manage the movement of the bridge in a large seismic event," said Anziano.
Most of the faulty bolts are accessible, but about one-third are already installed and hard to reach, which makes it impossible for the contractor to remove. One idea is to put a collar around those rods to reinforce them in case of an earthquake.
"Any solution that we put in place will cause this to perform as it was designed to perform," Anziano said.
"We have surmounted far greater engineering challenges than this one in getting this bridge constructed and I have no doubt that we will get through this one as well," said Metropolitan Transportation Commission Executive Director Steve Heminger.
Caltrans does not expect a delay in opening the bridge by Labor Day. They said they can work on the fix while finishing up other aspects of the project.
They also have no idea how much the fix will cost and whether the contractor, manufacturer or taxpayers will have to pick up the tab.