Oregon's planned test of taxing drivers by the mile instead of the gallon of fuel has hit a slight bump, but it's going ahead.

The last we heard of the proposal, a pilot project was planned this fall in Eugene. Now the one-year test is planned in Portland starting in March.

For an update, the Democrat-Herald checked with Jim Whitty, manager of the Office of Innovative Partnerships and Alternative Funding in the Oregon Department of Transportation.

The test will involve about 300 volunteer motorists, not yet selected, whose cars will be equipped with a Global Positioning System receiver. The gizmo will record how many miles the vehicle has been driven.

When the participants buy fuel at either of two stations in the Portland area, they will be charged a road tax based on the reading in the receiver. They'll also get a refund for the state gas tax included in the price of gas.

If they buy gas at other stations, they'll have to go to a stand-alone reader, not at a gas station, to have their mileage recorded and refunds figured.

Before the main pilot project gets started, ODOT this fall plans to do a test in the Salem area, where 20 ODOT employees have been signed up to drive around for 60 days with the devices in their cars. They won't have to pay any fees but will check to make sure the technology works.

The project is the outgrowth of the Oregon Road User Fee Task Force, created by the 2001 Legislature to look for alternatives to the fuel tax as the sole means of paying for roads.

The Legislature was concerned that with improvements in mileage and the development of vehicles that run on fuel other than gas or diesel, the state likely will run short of money for maintaining or building roads.

U.S. transportation officials are interested, too. The Federal Highway Administration has given Oregon $2.1 million toward the $2.9 million cost of the mileage-tax test.

Whitty said the problem with the original plan was that station operators in Eugene, most of them affiliated with major oil companies, were reluctant to take part.

"We had interest from one of the majors in perhaps assisting us, but that melted away," Whitty said.

Whitty said the project then turned to Portland, where it found an independent dealer with multiple outlets. He didn't name the dealer because there's no contract yet.

The plan is to have two Portland stations for the project volunteers to buy gas and have their receivers read.

When the project was first reported, a couple of years ago, it made the national news. Ever since, Whitty has been correcting critics who believe the system will lead to government surveillance of individual drivers.

The GPS units, he points out, will send out no signals, just receive them.

Unlike the OnStar system in General Motors vehicles, cars with the state receivers cannot be tracked.

Further, Whitty says, in order for any tracking to take place — even if the technology allowed it, which it doesn't — a law would have to authorize it.

"Does anybody think we could get such a law passed?" he asks. "We won't."

If the Oregon test works, don't expect mileage taxes to replace the fuel tax — now 24 cents a gallon in Oregon — anytime soon.

Whitty believes the system's potential for raising road revenue won't be realized until 10 years from now.

Also, he says, it's a pipe dream to think that Oregon can do this on its own: "I think it has to be taken up on a national basis, and I believe it will be."

He notes that transportation bills now pending in Congress would authorize commissions that are based on Oregon's Road User Fee Task Force.

"There is interest in what we're doing," he said.

Betsy Imholt, an administrator working with Whitty and the task force, said that in the Portland test, the mileage fees would vary.

A control group among the test volunteers will pay the gas tax as usual. A second group will be paying 1.2 cents a mile. And the third group will pay either of two rates: 10 cents a mile for driving during the morning and evening rush hours, and 0.4 cent a mile at other times.

For driving out of state, as recorded by the onboard receivers, no mileage fee will be charged.

Whitty explained the experiment could not easily be run in a less urban area — the mid-valley, for example — because the federal government wanted it to test congestion pricing as well as a straight mileage tax.

For more on the mileage tax project, go to http://egov.oregon.gov/ODOT on the Internet.