Every year here in Philadelphia, our public transportation company (SEPTA) threatens fare hikes and service reductions. If that were to happen, ridership would decline, perpetuating the downward spiral. There's a constant cry for dedicated state level subsidizing, but no one knows where the money would come from.
Now, I understand this wouldn't work everywhere, but I say, tax the living SHIT out of gasoline at the wholesale level. Make those prices sky high. I'll bet that would reduce demand.
So many people I know drive 15 minutes to work every day. Instead of 25 on a bike. Or 15 on a bus. Or a nice walk on a lovely summer day. Laziness is a major factor in why consumption is so great. Even with prices going up lately, I see very little change in driving habits. If gas were $10 a gallon and public transportation were super cheap and expansive, you better believe people would drive less.
You can't just ask people to not drive for a day. Gotta hit 'em where it counts.