Are user fees a middle-class tax hike or a fairer way to pay for infrastructure in Pittsburgh region?

“We have a grasp of what this stuff costs, but we don’t have a grasp on long-term financing of it,” said Stan Caldwell, adjunct associate professor of transportation and public policy at Carnegie Mellon University.

As the Highway Trust Fund has eroded over time, project fixes have been kicked down the road, and user fees have become more disconnected from the people who pay them, transportation experts said.

Drivers who use the Pennsylvania Turnpike complain their tolls fund urban public transit projects in Pittsburgh and Philadelphia, and public transit advocates complain federal transit spending remains too low. Pennsylvania Gov. Tom Wolf, a Democrat, created a task force last month to look at alternatives to the gasoline tax.

“The federal government is not addressing this, and so therefore the states have to keep doing it on their own and keep coming up with their own plans to fill in the gaps,” Mr. Caldwell said. “The system we have now, it can be argued, is a result of a lack of addressing this at the core.”