If it's the heavy trucks that are causing the corrugations, how do you explain corrugations in minor roads? I have an unsealed road beside my place. It starts at the intersection with the sealed highway. The road is mainly used by light vehicles, and when a heavy does use it, the speed is low because they have either just turned into the road or are coming out of a dip where the creek crosses the road. Also, the distance between the crests of the corrugations is shorter than the footprint of a truck tyre.
After following the conversations here, I get the feeling that no one watched the video which show a demonstration of how these corrugations form.