A better formula would be (mileage) * (((highest axle load)^4) * no. of axles) * (per mile fee), which would incentivise loads being evenly spread over as many

A better formula would be (mileage) * (((highest axle load)^4) * no. of axles) * (per mile fee), which would incentivise loads being evenly spread over as many axles as practically possible. This would be a huge boon to road health and longevity.