You could also argue that because money is fungible, raising the gasoline tax, while raising money for bridge repairs, could free up money that would have gone to bridges and makes it available to some other use. It's not clear that raising the gasoline tax would make more money available for bridge safety.Any more than using a lottery to fund schools has made more money available for schools. (A relatively recent NBER working paper (as .pdf) suggests that lottery profits increase school spending by thirty to fifty cents on the dollar.
LAWS OF CONSERVATION. Phil Miller at Market Power.