[isostatic]

Petrol tax goes into the exchequer, it's not ringfenced for the roads. Most roads are funded from council tax in any case.

Petrol and VED raises £33b a year, but total road spending (including local councils) is under £10b.

The solution to rationing road usage and paying for their use is road charging (with heavier vehicles paying proportionally more based on axel weight, and different charges depending how congested the roads are) which should pay for the maintenance of the roads, new road building, and renting the land to have the roads on.