Comment by nradov

Exactly because of the fourth power low, almost all of the road damage comes from the heaviest vehicles: class 7 and 8 trucks as well as buses etc. Even the heaviest passenger vehicles are negligible by comparison. And the weight of semi-trucks hasn't been "ever increasing": normal maximum weight has been fixed at 80,000 pounds for decades.

In some areas the roads are shit due to weather conditions, mainly frost heaves. This has little to do with vehicle damage.