Under the proposal discussed Friday, a one-tenth of 1 percent tax on land only could raise $43 million annually, said Larry Walters, representing the Lincoln Institute of Land Policy, a nonprofit education group. A four-tenths of 1 percent tax would generate about $171 million.

The Tax Review Commission took no action on the idea beyond creating an ad hoc committee to investigate the technical feasibility of administering such a system.

Walters said the biggest advantage of a land-value property tax is its stability and potential for future revenue growth. That is in contrast to the gas tax, which falls notoriously short in covering exploding transportation demands.

"It is very, very risky to say we're going to use the gas tax as the foundation for funding transportation," said Walters. "It is really shaky going forward."

There has been a widening gap during the past decade in vehicle miles driven and taxable sales of gas, according to Walters' figures. That's not too comforting in light of estimates the state needs $30 billion to fund transportation projects through 2030, but will have only $6.5 billion available with existing revenue sources.

Another legislative task force that spent months brainstorming the issue recommend drastic action: a 5-cent-per-gallon hike in the gas tax, a quarter-cent bump in the state sales tax, increased registration fees and shifting money from other state programs.

Lawmakers this year did siphon tens of millions of dollars from other programs into highways, but rejected all tax increases. There is no telling whether the proposed land-value property tax plan would be any more politically saleable.