The damage to the road is proportional to the fourth power of the axle weight. Take a look at this chart: https://streets.mn/2016/07/07/chart-of-the-day-vehic

The damage to the road is proportional to the fourth power of the axle weight. Take a look at this chart: https://streets.mn/2016/07/07/chart-of-the-day-vehicle-weight-vs-road-damage-levels/ https://streets.mn/2016/07/07/chart-of-the-day-vehicle-weigh... and this article https://www.denenapoints.com/relationship-vehicle-weight-road-damage/ https://www.denenapoints.com/relationship-vehicle-weight-roa... From the article: "Or where an 80,000-pound 18-wheeler full of cargo is compared to a 4,000-pound passenger car, the truck is 20 times heavier than the car. But taking the 4th power of the relative loads, the semi would cause 160,000 times more road damage than the car. (But my simple calculation is not taking into account the effect of any weight distribution caused by the greater number of axles on the big rig.)" Even taking into account the number of axles, say, five on the lorry and two on the car we have 2 000 pounds per axle for the car and 16 000 pounds per axle for the lorry. That is a factor of eight, 8^4 is 4096, still a large number.