Thursday's shutdown made clear that without BART's Transbay Tube, there are not enough buses, ferries and bridges to comfortably handle the load of people needing to get back and forth across the bay.
Business and transportation leaders say the time to start doing something about that is now.
Damage to a 400-foot stretch of BART track and its electronics closed the Transbay Tube and threw Bay Area commuters into turmoil. They either had to stand in lines for transit alternatives or sit in gridlock on congested roadways.
It was both a nightmare and a wake-up call.
"Clearly as a region we're not prepared for a big disaster and yet apparently one is in our future and we better think about it," said Jim Wunderman of the Bay Area Council.
BART's tube across the bay carries the equivalent of a six-lane freeway. Without it, the region's best response plan still comes up short.
Thursday's damage was fixed within 14 hours. Damage from a disaster or terror attack could take much longer.
"We're probably one bridge short of what we should have, and we only have one tube that crosses the bay with BART, our major fixed rail system. If that goes out we're down to zero, that's what happened yesterday," Wunderman said.
The idea of another bridge, dubbed the Southern Crossing, was abandoned years ago. It would have crossed the bay from Highway 380 to Alameda. Wunderman thinks that deserves another look.
But Mineta Transportation Institute Executive Director Rod Diridon thinks anything involving more cars on already congested roads is a waste of time.
"We need at least one more bore or tunnel under the bay for BART," Diridon said.
Diridon said the Bay Area has to plan for population growth, and that high-capacity BART trains are the solution.
California's population is expected to double by the 2050s and 2060s, he said. "Although that's 40 years away, it takes 20 years to build another tunnel for the BART system."
Cost estimates for another tube range between and $3 and $10 billion. But would Bay Area residents be willing to help pay for it?
"Yes, definitely. I love taking BART actually," said commuter Freddie Gandeza.
"There were people backed up on ferries and everything was a mess yesterday, and I definitely think we need some alternate means," said San Francisco resident Elizabeth Kiss. "However how it should be funded is beyond me."
There are different ways Bay Area residents could be asked to help pay for it. Examples include an increase in the sales tax or a bond measure or possibly higher tolls.