Washboard road results from the instability of a granular surface under the action of rolling wheels. Here, a hard rubber wheel rolls on the edge of a rotating table covered with a bed of sand. The wheel suspension is simply a lever. The table is 1.2 m in diameter.
The movie is in real time.
Here are two more movies in slow motion of the onset, and of the fully developed ripple pattern.
Go here for downloadable versions of the movies in other formats.
See Washboard Road abstract for a publications about this effect.