My friends have had plans for this situation since highschool. We meet at our buddies house in the woods. We commandeer one of his neighbors tanks (his neighbor has one of the largest private collection of tanks). We take said tank (which can run off pretty much any liquid that burns) and drive it to SF where we then forcibly take control of a ferry and drive ourselves and the tank with enough supplies to sustain ourselves for at least a month on Alcatraz.

We figure by the end of the month most zombies will have decayed beyond mobility and should any other humans attempt to join us that we don’t want on the island with us… Well we have a tank.