Here are some tips from our friends over at the Treasure Island Music Festival on getting to the festival while BART is on strike:
We highly recommend carpooling to downtown SF, where shuttles to the festival will be running from Bill Graham Civic Auditorium. A limited number of parking passes are still available for Sunday. If you have a ride or need a ride, there is a TIMF Facebook event to help you coordinate with like-minded individuals.
Ride-sharing sites like amovens and RickyRides have specific TIMF event pages that serve the same purpose. The Bold Italic are offering a party boat to the island, which will be picking people up from SF and Oakland.
Finally, you can also check out a fuller list of transportation options on the TIMF site. KQED has compiled all the rest of your choices for commuting right here.