The original note, as written at the time
We could charge for car road use, and single (and numbered) car user road use. We could also have special days when particular people on a predetermined rota get to use the road for free.
Ongoing development
Charging for car road use, and for single-occupant car use, with special days when particular people on a predetermined rota get the road free.
The rota is the part that makes it fair, and it is the part nobody proposes. Road pricing is normally designed as a congestion charge — a flat penalty that falls hardest on whoever has least choice. A rota turns it into a queue that everyone takes a turn in.
The second part, charging for single-occupancy, is the more accurate signal, because a car carrying one person is using the same road as a car carrying five and delivering a fifth of the benefit. That is not a moral judgement about drivers. It is a measurement of throughput.
The mechanism has to be invisible or it fails. A toll booth reintroduces the congestion it was built to remove, so the charge should be automatic, per journey, itemised, and visible in the same place the person pays for fuel or phone.
The honest risk is surveillance, because a road-pricing system is a movement-tracking system unless it is designed not to be. That is a solvable problem with the right architecture — local computation, aggregated billing, no location history retained — and it must be solved before the first camera goes up, because afterwards it never will be.
The free-day rota also solves a political problem. Every road-pricing scheme in history has been defeated by the claim that it is a tax on the ordinary driver. A scheme that gives everybody some days back is harder to attack.
Price the road, and give everyone a share of it.