The $4.3- billion transportation funding package also includes a registration fee increase for electric and fuel-efficient vehicles, a transit payroll tax increase and a 46-cent-per-gallon gas tax. The road usage charge would increase from 2 cents a mile to 2.3 cents. The intent is to avoid layoffs and funding gaps for infrastructure investment.

Opponents collected enough signatures to refer key parts of the bill to a statewide vote in November, and the governor last month called on the legislature to repeal the entire bill and avoid a funding limbo for the Oregon Dept. of. Transportation. However, whether that is possible due to the pending voter referendum is being debated.

But with the federal gas tax frozen in place for decades, many transportation advocates have long argued for a road user fee. "The rest of the country was waiting for us to pass this into law," said Jim Whitty, former Oregon DOT head of innovation, in an MIT Mobility Forum online event Feb. 6. He noted that transportation departments in states such as Minnesota, Hawaii, and Utah are pursuing similar efforts, and have consulted with Oregon DOT.

While parts of the bill, such as the gas tax increase, will be referred to voters in November, "the per mile provision was left in," he said.

The process isn't perfect, he acknowledged. "If a vehicle owner chose GPS, [consequent revenues] are limited to roads in the state. It’s like filling up in Iowa, then driving into Oregon. Most taxes are that way – they are good estimations rather than precision," he said, adding that trying to pursue more accurate mileage tracking would be too invasive of privacy.

Oregon DOT does not track travel patterns and deletes mileage data after a short time, he added.

"Gas taxes were great when we had no technology. Now we do," said Robin Chase, cofounder of Zipcar. "How do we get to user fees that actually reflect the costs?" She noted that the traditional process of selecting one bidder to implement a program, such as a tolling system or congestion pricing, removes any incentive to upgrade the technology because the supplier typically has a long-term contract.

Frederic Charlier, founder and CEO of ClearRoad, concurred: "Inertia is the challenge. When an agency has invested millions in building one approach and equipping vehicles with devices, changing gears is difficult. That’s where we and other companies have tried to bring in new technology."

ClearRoad offers digital tools utilizing apps and in-vehicle devices to facilitate road user fee charges, manage tolling and implement low-cost dynamic pricing solutions, such as in the city of Bogota. "They said, we're a developing country; we need something cheap and scalable," said Charlier. "We can't afford sophisticated cameras and readers." Instead, the congestion pricing is enabled through existing traffic lights and smartphones. "Road charging can be low-tech. There is room to do anything you can imagine. Creativity is the limit."

While Oregon DOT has a tax on heavy trucks based on weight and distance traveled, lighter-weight trucks may eventually undergo a new road usage fee, said Whitty, adding, "Let's get the basic system in first."