RALEIGH – Let me go way far out on a limb and predict that there will not be a groundswell of popular support anytime soon for the creation of a new set of toll roads and mileage fees in North Carolina. However, I do agree with Kenneth Orski, publisher of transportation research via his Urban Mobility Corporation, that highway pricing might be close to the “tipping point” made famous by author Malcolm Gladwell.

Orski, a former administrator at the federal Urban Mass Transportation Administration and a 30-year veteran of transportation-policy wars, argued in a recent edition (not yet online) of his newsletter, Innovation Briefs, that “highway tolling and private financing are gaining new converts among governors and state transportation officials, in state legislatures, and in the media.” As evidence, he pointed to proposals since the beginning of the year in California, Virginia, Maryland, Texas, Washington, Indiana, Utah, Georgia and South Carolina to set up or expand public-private partnerships to build tollways. He might have included recent activity by North Carolina’s new authority to create a priority list for new tollways in several corridors across the state.

As for charging motorists to use state highways according to miles driven rather than gasoline consumed, there is at least some conversation about an idea that, until quite recently, was viewed as purely theoretical, politically impossible, or both. The theory, at least, is indeed sound. Gas taxes have always been a rough approximation at best of a user fee, a way to assess the cost of building and maintaining unlimited-access roads according to how much wear and tear individual motorists impose on them. Along with weight-based charges on trucks (which appear to be far too low) and a series of flat fees on automobile and driver registrations, the gas tax is the primary means of charging users.

It suffers all the problems of being an approximation. Despite the rise of the SUV, average fuel economy in the motor-vehicle fleet has increased. Motorists effectively pay less in tax per mile driven than they used to, not a trend likely to keep highway investment sufficient to accommodate growing traffic. North Carolina’s “solutions” to the problem, consisting of a variable component to its excise tax on motor fuels and a lot of wishful thinking, are inadequate and themselves politically unsustainable.

Meanwhile, it has become technologically feasible, using the global-positioning system, to install markers in automobiles and track not only their mileage but also their use of particularly congested roadways (thus allowing for peak pricing, much as electrical power is priced to discourage low-priority usage during peak times). If this still sounds too sci-fi for you, it’s worth noting that Germany already successfully operates a satellite-based system for charging trucks to use some 7,500 miles of autobahns, while demonstration projects are underway in Oregon and Washington to use GPS-based tracking technology to price roads. The U.S. Department of Transportation is preparing to fund five additional pilot projects around the country.

The obvious barrier to phasing out gas taxes in favor of mileage-based pricing is a legitimate concern about the reliability and safety of the system. How would motorists challenge errors in their monthly bills? Could the tracking information be hacked and misused to invade our privacy?

It would still be good news if policymakers began a serious discussion of these challenging issues. It would mean the tipping point is close at hand.

Hood is president of the John Locke Foundation.