GAO

Safety would win hands down for passenger rail, but for-profit railroads have a bottom line to consider. Regulators have proposed reduced train speeds, opposed by railroads, to prevent fiery derailments that have resulted from shipping shale oil.
Oct 18, 2014   The Gazette
In this opinion piece on how to pay for roads, Noel Popwell gives 5 reasons for switching from gas tax to vehicle-miles-traveled (VMT) fee revenue collection - even if the Highway Trust Fund wasn't facing insolvency next year. Obama is opposed to it.
Aug 18, 2013   Streetsblog Capitol Hill
Justin Hyde is firmly in the camp that 'Vehicle-Miles-Traveled' (VMT) fees are coming - and the release of a GAO report last month may support that contention. Privacy concerns from GPS and collection costs are challenges that were considered.
Jan 14, 2013   Motoramic (Yahoo! Autos blog)