For most /*BART*/ commuters, traveling from the East Bay to San Francisco, the alternative mode of transportation will be their cars.
"That's probably going to translate into about 60,000 additional vehicle trips" Metropolitan Transportation Commission (MTC) spokesperson John Goodwin said.
The worst bottleneck is expected to be at the bay bridge; the MTC is advising drivers to be at the toll plaza an hour earlier.
Carpooling may help ease the expected traffic.
Friday, the commuter matching service Ride Share had a spike in the number of calls. On any given day they get between 25 and 50 calls; today it was over 200.
"And so we essentially match them up, they can call up a series of people and say, 'Hey I am interested in carpooling, would you be willing to carpool with me,'" 511 spokesperson Kit Powis said.
By Friday afternoon, some of commuters still did not have a sure Plan "B."
"I might even consider staying in the city with friends if it came to that, because it would be insane to try to get into San Francisco and drive," Rockridge resident Julie Franklin said.
"I would have to take a cab, maybe, it would be really expensive, probably about 20 or 30 bucks," Berkeley resident Patrick Baker said.
AC Transit is also an option. There are 675 buses serving Alameda County. A few buses will be added, but they only have a few extra coaches.
The ferry service in Alameda County will expand, offering twice the number of trips. The city of Alameda will charter three extra boats, one from the Blue and Gold fleet.
"So the fare is $6.50 on the Alameda Harbor Bay Ferry, that's one way, and $6.25 cents on the Alameda/Oakland Ferry, that's one way, and no you don't have to have exact change, although that would help on Monday," Alameda Ferry manager Ernest Sanchez said.
Zip cars may be a new alternative. Commuters can rent a car by the hour or by the day.
For others, telecommuting may be the most sensible option. Some businesses have already offered some employees the option of working from home Monday.