When I first ran into the 4th power stuff, I quickly calculated taht a fully loaded truck damages as much 160,000 cars.
This is incorrect, however.
The 80,000 lb truck has 18 wheels, so if the weight is spread evenly, each truck wheel only ("only"? ha!) has a little over 4 times as much weight as a car wheel.
That means each wheel does about 390 times the damage of a car wheel. Then there are 4 1/2 times as many wheels for about 1750 times the damage.
Still substantial, but a tiny fraction of my initial estimate of 160,000 times the damage.
I recall having heard a fully loaded truck does about as much damage as 10,000 cars. I guess this could be right (or even way conservative) if you consider average miles driven per year.
(sorry, I just had to geek out here)