[pepsi_junkie]

And, how about requirement that all of these mileage taxes go solely to building and maintenance of roads

That's what they did with tolls the NJ Turnpike and Garden State expressway in New Jersey. They were chartered to use tolls to pay for the construction and then the tolls would go away. They never did, for decades they just kept adding to the roads, spurs that went nowhere, just to keep that toll money coming in. Now they don't even bother with that. Those temporary tolls are damned permanent.

And so too will any new tax be.

[Publius]

The New Jersey Turnpike's revenue bonds expired in 1995. At that point, the tolls could have come off, but then the state DOT would have had to pay for all the work necessary to maintain the physical plant of the turnpike. That would have meant a gas tax hike. Gov. Whitman decided to let the Turnpike Commission float another set of revenue bonds to pay for them. I believe those bonds will be paid off in 2025. At that point, a similar decision will have to be made.

The Garden State Parkway's charter permits it to exist in perpetuity with the counties through which the Parkway runs getting a cut of the proceeds.