In theory, yes. But it hasn't been raised since the 90's and since it's a per-gallon tax and not a percent tax, its funding has decreased as Americans buy more efficient cars and thus fewer gallons of gas. I don't have links, but I've seen graphs indicating that the fund regularly runs at a shortfall now, and getting worse.

Maybe you can start digging from here: See here: https://www.nytimes.com/packages/html/newsgraphics/2011/0119...

And here: https://en.wikipedia.org/wiki/Fuel_taxes_in_the_United_State...

$25 billion received via gas taxes at the federal level in 2006 (60% spent on roads). $70 billion spent by feds in 2012.

In practice, the gas tax covers only a small portion of road maintenance costs.

http://www.subsidyscope.com/transportation/direct-expenditur...