Most of us are ok with that kind of government spending.
As of 2010, about one-quarter of all vehicle miles driven in the country use the Interstate system. The cost of construction has been estimated at $425 billion (in 2006 dollars), making it the "largest public works program since the Pyramids." The system has contributed in shaping the United States into a world economic superpower and a highly industrialized nation.
Most people might be OK with it, but it’s not the Federal government’s job ... especially as you said “so the population can maintain a healthy living density”.
That sounds very much like collectivism to me ... for the greater good sort of thing.
Conservatives fall into that trap too.