"The decision to build a road is a permanent commitment to the traveling public. Not only will a road be built, but it must also be routinely maintained and reconstructed when necessary, meaning no road is ever truly “paid for.” […] The Asset Value Index, was developed to compare the full 40-year life-cycle costs to the revenues attributable to a given road corridor or section. The shorthand version calculates how much gasoline is consumed on a roadway and how much gas tax revenue that generates. […] Applying this methodology, revealed that no road pays for itself in gas taxes and fees. For example, in Houston, the 15 miles of SH 99 from I-10 to US 290 will cost $1 billion to build and maintain over its lifetime, while only generating $162 million in gas taxes. That gives a tax gap ratio of .16, which means that the real gas tax rate people would need to pay on this segment of road to completely pay for it would be $2.22 per gallon."

The Real Cost of Roads - Smogr