How on earth will the state fill its massive mass transit budget shortfall? If the Regional Transit Authority (RTA) gets its way, motorists will help foot the bill.

According to the Chi-Town Daily News, RTA officials are lobbying lawmakers to increase the state’s fuel tax to cover the costs. By tacking on 8 cents per gallon, as outlined by State Rep. John Bradley’s bill, the state could generate an extra $500 million annually, which legislators could then turn around and authorize bonds to the tune of 10 times the original amount of revenue. An average motorist would pay 80 cents more for a 10-gallon fill-up and and RTA would take home $2.7 billion in funds for capital projects over five years, half of what the transit officials say they need.

RTA seems to have powerful allies in Springfield. Both Senate President John Cullerton and House Speaker Michael Madigan say that they’re open to an increase in the state’s gasoline tax to fund billions of dollars in highway and mass-transit projects. The Tribune has more:

House Speaker Michael Madigan will support a proposal to raise the existing 19-cent-per-gallon motor fuel tax to 27 cents—a boost that could raise $500 million a year to fund bond payments on a $5.9 billion transportation repair plan, a Madigan spokesman said.

Senate President John Cullerton also told the Chicago Tribune’s editorial board that increased motor fuel taxes and higher vehicle fees should be considered “on the table” for what he called an Illinois “stimulus” package that would fund school construction as well as road and transit projects.

Bradley’s proposal isn’t exactly unique. This year, lawmakers in California, Massachusetts, and New Hampshire are introducing bills that would raise gasoline taxes for road and bridge repair. Top leaders in Iowa, Ohio, Maryland, and Michigan are contemplating hikes, as well.

Even though the Illinois fuel tax hasn’t been raised in 18 years, motorists still pay well over the U.S. average for a gallon of gasoline. As the Trib points out, 50.8 cents is added to each gallon if state and local taxes are added to the federal tax rate of 18.4 cents per gallon. That’s the 9th highest average (PDF) in the nation.

But when lawmakers levy taxes, they should do so to raise revenue and, when possible, to discourage destructive behavior. A gas tax passes both tests. Not only would the state net cash -- a major need given the budget deficit and declining fuel-tax revenues -- but more commuters would consider fuel-efficient vehicles and/or use public transit more often. A simple tax credit could be distributed to vulnerable segments of the population to offset the increase.

Meanwhile, Transportation Secretary Ray LaHood is making his own moves federally, telling the AP that he might consider taxing motorists based on how many miles they drive rather than how much gasoline they burn. Policymakers in Minnesota, Oregon, and elsewhere are currently experimenting with this model, which originated in Portland. The New York Times explains how it works:

The system worked by means of an onboard “mileage-counter,” which then notified participating gas stations in Portland how far the vehicle had gone. While the owner filled up, the gas tax was deducted from the gas bill, and the “mileage tax” was added. (If the “mileage tax” is set at 1.2 cents a mile, the pilot found, the average driver would pay about the same amount for the mileage tax as for Oregon’s 24 cents-a-gallon gas tax.)

While the technology still needs tweaking before its applied broadly, the VMT has appeal. The highway fund, reliant solely on gas tax revenue, has grown insolvent thanks to a decline in driving. Not only is the VMT more stable than a gas tax, which is subject to wild price swings, but it charges those that use roads most often. Matt Yglesias offers a dissenting take here.

Ultimately, Illinois and the nation need to find sustainable revenue sources to fund the vast and long-ignored mass transit projects. A gas tax hike may be a step in the right direction.

Image used under a Creative Commons license by Flickr user abraxas3d.

UPDATE (3:10PM): Department of Transportation spokesperson Lori Irving has shot down LaHood's idea, claiming  "the policy of taxing motorists based on how many miles they have traveled is not and will not be Obama administration policy." So scratch that one.