Caltrans says it plans to spend about another $8 million, or more, just to figure out which bolts might also be at risk.
Officials are testing 11 giant bolts, similar to the ones that broke on the new Bay Bridge.
"We're taking one from the base of the tower, one from the top of the tower, a couple from the anchorage for the main cable," said Bay Bridge Spokesperson Andrew Gordon.
Some of the bolts are spares. Others were actually pulled out of the bridge and replaced. All will be anchored down at one end and screwed into a jack at the other. The jack slowly pulls on them until they break. All the while, the threaded end is sitting in salt water that slowly eats away at the steel.
It's designed to simulate years of traffic and rainwater.
"The testing that we did last year told us that there is no short term concern with the safety of this bridge. What we're talking about is long term, over decades," said Gordon.
The steel bolts for the Bay Bridge were galvanized, a process that makes them harder but also more brittle because of the tiny cracks it can cause.
"It's a well-known phenomenon. We've known this forever; we have standards on this that, you know, you do not perform galvanization on these really hard bolts," said materials engineer David Xu.
But with the galvanized bolts already in place, Xu says Caltrans is doing the right tests.
"Yeah, these are going to be very, very expensive. The machine, you know, there's probably only a dozen of those kinds of machines in the nation," said Xu.
Caltrans will do more testing in a lab and come out with recommendations for how to monitor and maintain those potentially brittle bolts over the life of the bridge.
The millions being spent now could be just the beginning and now the State Senate is investigating, with a hearing scheduled later this month.