FOR THE RECORD
If the governments decided to sell off all their highway and road assets to private investors (and use the proceeds to pay down their debt) - I'd be 100% OK with it.
You might ask - why would a liberal support that?
Its pretty simple. The governments' (I mean all levels) subsidization of infrastructure targeted for primary (and near exclusive in most cases) use by private passenger vehicles and freight transportation by truck favors one particular mode of transportation, giving that mode an artificial market advantage. I believe our resident economics genius, eflatminor, would agree that is the case.
Its my belief that if it were up to the market entirely to determine which mode was best, private auto-mobile transport would fall behind and more efficient modes of transportation would become more prevalent. These modes - from the simple economies of scale that you get from buses as opposed to private cares - all the way up to full life-style changes where people place a higher priority on being located closer to work to enable them to walk or bike - are not only more economically efficient, they are better for the environment.
So there you have it. A liberal that can't see why big government needs to meddle so much in the transportation market.
EDIT: Once we take away the artificial advantage in the market given to passenger vehicles, we can also eliminate other "green" subsidy programs, as these programs won't be needed once the market is levelled for ALL modes of transport.