The Palo Alto ATOC organizers posted information about event parking for the Amgen Tour of California prologue on Sunday at the Palo Alto Tour of California website. You can find detailed information about road closures, event parking, public transportation options, free shuttles, and bicycle valet parking. If you're driving, you'll want to pay attention to the event parking maps.
Spectators are encouraged to use public transportation to get to the race. The trains will accommodate up to 1000 riders, although they have limited bicycle car capacity and are encouraging you to leave your bike at home.