I think Macquarrie (the world's largest independent infrastructure financier) Bank did this in Bremen.

It didn't work, the cost of the tunnel toll was too high so people didn't use it.

On the other hand, the Toronto 407 highway did work: the government signed a 99 year lease with no regulation on tolls. Since the parallel untolled highway is jammed, the tolls have gone through the roof.

Another common trick is the Birmingham Bypass one. Trucks do far more damage to a road surface than cars-- (the damage is as a cube of the axle weight, so a 3 tonne truck can do 27 times the damage of a 1 tonne car). So the company running the Bypass priced trucks off the road-- they go by the free government paid for road.

We have lots of public private partnerships here in the UK for schools, hospitals etc. Basically they are a way of transferring fiscal burdens onto future taxpayers. The 'risk sharing' element is often quite illusory.

Georgia being Georgia, cutting the gas tax will be quite popular. Ironically, the poorest people don't even have cars, or don't drive much if they do, so it doesn't help them much. But they would never vote Republican (or even vote, in most cases). Whereas the suburban-dwelling SUV driver is a key Republican demographic, ditto the rural voter with a pickup truck. Roll on Georgia!