So, a lot of states have been changing the design truck from the federal standard to something heavier based on the traffic they are seeing. So, if the federal government is going to accept the heavier trucks, they are going to have to accept the affect these trucks have on the nation’s highways.
Or just do what railroads did and design roads for the heaviest train of trucks full time forever, but that is kind of expensive and the federal government doesn’t want to spend the money if they don’t have to.