A report released by the Rand Corporation, one of the first modern think tanks, proposed moving highway funding away from being based on fuel taxes and tax miles driven; such a “vehicle miles traveled” (VMT) system would make it easier to generate revenues in an era where fuel economy is increasing among freight carriers and many cars and trucks are moving to electric power and other alternative energy sources.

There are quite a few economic side effects to moving to a VMT beyond the privacy issues brought to the fore by checking on every mile driven by a vehicle. One effect is to discourage energy efficiency in trucks; the current system rewards trucks that use less gas. The cost of gas will encourage fuel efficiency, but not as much as when it is taxed

A second effect would be to move things towards intermodal transport; that would favor container transport over other modes, for containers move more easily onto trains than other cargo. Plans to have rolling highways, where trucks could hitch a ride whole on truck-carrying trains, would speed up in a VMT setting.

A third effect would be to discourage rural locations. Urban deliveries are less fuel efficient on a per mile basis, but would have an advantage over an easy-to-get-to rural location. State and national governments often have to spend extra effort to get economic development to rural areas, but this would penalize putting facilities in remote locations.

Officials will also need to figure out whether traveling is something bad that we want to tax. If not, there might be wiser ways to raise money for the transportation budget.

Sources:
http://www.landlinemag.com/todays_news/Dai...0/021110-02.htm
http://www.rand.org/news/press/2010/02/10/...highway_traffic