Why does a road ripple like a washboard? Here comes the science...

The good news is that the men in white coats have figured out why washboard roads develop on sand, gravel or any other loosely-surfaced roads. Above a certain speed, any linear force interacting with the surface causes the force to skip over the surface like a rock skipping over the water. The ripples are caused by the force alternately being "thrown off the surface" and then touching down again.

The issue isn't about oscillating car wheels, nor wheels at all for that matter. The scientists performed their experiments with a flat, inclined un-suspended plow blade; when it got above a certain speed the plow blade created ripples just like a wheel does.

The bad news is that it will be long time before the phenomenon can be stopped: "Just about any time a malleable surface is acted upon by a sideways force, you will get ripples." Since it doesn't look like ripples are going away, scientists could turn their attention to suspension systems that will "eliminate the bumpy ride." Hat tip to Michael S

[Source: Science Daily]

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