So ist es etwa richtig. Die Piste muss relativ häufig und schnell befahren werden und der Unterrgrund muss sich gut verformen können. Hier die Erklärung aus einer Kolumne der University of Alaska Fairbanks, Geophysical Institute:

Bumps in the road surface cause the tire to hop in the air. Where the tire crashes down, it forms valleys by spraying sand and gravel forward and sideways. The moving tire ramps out of the valley and hops again. Thus, the washboarding process repeats itself.

Washboard spreads across the road as other cars repeat the action of the car that initiated it. Mather pointed out that bumps cause cars to react the same way even though some are heavier than others and have different suspension systems.

He concluded that other than slowing to about 5 miles per hour or using balloon tires that would cushion the road but would also inspire the need for barf bags, there wasn't much drivers could do to prevent washboard roads from forming.