Science fiction writers have pictured flying cars in the 21st century, but surely not a dashboard device that would count every mile motorists drive and bill them for it. Yet that is among the ideas that have passed into the realm of possible as New York and other states consider how to create new tax revenue.

Currently, the main source of funds for road construction and upkeep is a tax that is levied on every gallon of gas purchased. The more fuel sold, the more money there is to spend on roads, bridges, and transit.

Today, however, Americans are driving fewer miles. In fact, they are driving about the same number of miles today as they did in 2005, when the USA had 8 million fewer people. This equates to 30 billion fewer miles driven from November, 2007 through April, 2008, as compared to the same period one year prior. Part of this is due to the higher gas prices; another reason is the increase in fuel-efficient and alternate-fuel cars on the road.

The result? Tax revenue is falling; the money collected hasn't kept pace with the cost of repairs to our transportation system. New York is among many states with road funding problems. A likely answer is the Vehicle Miles Traveled (VMT) fee, which would replace the current per-gallon fuel tax. The technology used for a VMT system is a simple global positioning (GPS) device placed in each vehicle to track miles driven.

When you pull in to a service station to fill up, mileage data would be wirelessly loaded to a reader near the station pump. The tax would then be added to your gas bill. GPS systems can also tell who owns the roads you traveled on (by state, county, town, or village, for example), and allot tax revenues accordingly.

Many people argue that a VMT tax punishes the users of fuel efficient cars while rewarding the owners of gas-guzzlers, since each would be taxed equally on a per-mile driven basis. Under the current per-gallon based tax system, for example, the owner of gas-guzzling Suburban pays more tax than a fuel efficient Prius. One solution under review is to vary the VMT fee based on vehicle weight, mileage, fuel type, and environmental impact.

Under the VMTsystem, truckers and other large weight vehicles could pay more per mile due to the greater cost of upkeep of the roads and bridges over which they travel.

While many agencies believe the best solution to the problem of falling gas tax revenues may be to move to a VMT fee, privacy and policy issues must first be ironed out. Some people argue that Big Brother will be able to track a person’s every move, even the roads they travel on and how long they stop at a particular destination.

The reality is that the current system will run out of money if allowed to continue. Experts predict that the federal use of the per-gallon gasoline tax is likely to be replaced by a VMT fee by 2025. It will take at least this long to develop mileage-based revenue systems that can be tailored technically and politically to the needs of the states and cities.

If you’re interested in transportation policy, here is a report that may be of interest. Go to www.transportationfortomorrow.org/pdfs/press_release_011508.pdf for more details.