The survey is a little frustrating. As pointed out by The Sourcecommenter Ron, the first question asks how you get to Metro's (rail) stations. You are only allowed one answer, and this shapes what future questions you get to respond to.
Metro is posting parking survey promotional signs at some stations, but apparently not others. Damien Newton spotted the above sign at the Metro Expo Line Culver City Station, which features $2.5 million dollars worth of free parking. I haven't seen any sandwich board signs yet at the Vermont/Beverly or Wilshire/Vermont stations, which coincidentally feature no free parking. Readers - where have you spotted these signs? Is there a pattern to where Metro is deploying them?
Also, English appears to be the only language the survey is available in. Updated: Metro's Steve Hymon emailed: If you want to take the survey in Spanish, please text 323-688-4659 and type in the letter 'a' or find the Spanish survey on-line here.
Nonetheless, take the survey to get Metro's parking plan off to a good start.