Actually (and surprisingly, at least for me), this is not the case... The Vice article mentions a US PRIG study that showed that "user revenue only covered 48 percent of the costs of roads". [1]
Sorry I'm late coming back to this, but there's a reason I said "freeway network" and not "roads". For a variety of political and economic factors, local roads are maintained out of localities' general revenue. But they could easily be covered by an expanded gas tax, particularly if 1/6 of gas tax revenue wasn't redirected to transit.
[1] http://www.uspirg.org/sites/pirg/files/reports/Who%20Pays%20...