washboarding

thumb|Washboarding effect on a road Washboarding or corrugations is the formation of periodic, transverse ripples in the surface of gravel and dirt roads. Washboarding occurs in dry, granular road material with repeated traffic, traveling at speeds above . Washboarding creates an uncomfortable ride for the occupants of traversing vehicles and hazardous driving conditions for vehicles that travel too fast to maintain traction and control.

==Mechanism== Washboarding or corrugation of roads comprises a series of ripples, which occur with the passage of wheels rolling over unpaved roads at speeds sufficient to cause bouncing of the wheel on the initially unrippled surface and take on the appearance of a laundry washboard. Most studies of washboarding pertain to granular materials, including sand and gravel. However, other work suggests that the phenomenon may occur in material which has some binding of particles, e.g. clay-like soils.