# Roadway washboarding revisited

**URL:** <https://boards.straightdope.com/t/roadway-washboarding-revisited/220871>\
**Category:** Cecil's Columns/Staff Reports\
**Created:** [December 24, 2003, 5:31pm UTC](https://boards.straightdope.com/t/roadway-washboarding-revisited/220871 "2003-12-24T17:31:26Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![patchbunny](https://avatars.discourse-cdn.com/v4/letter/p/dc4da7/32.png) [@patchbunny](https://boards.straightdope.com/u/patchbunny)\
**Post date:** [December 24, 2003, 5:31pm UTC](https://boards.straightdope.com/t/roadway-washboarding-revisited/220871/1 "2003-12-24T17:31:26Z")

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Reintroducing an earlier topic, [What causes the “washboard” effect on unpaved roads?](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=221233&highlight=washboard+road), I’ve come across some more information on the rather annoying phenomenon.

Scientific American ran an article in January, 1963, entitled _Why do Roads Corrugate?_, by Keith Mather (p128-136). In the article, Mather examines the factors that create washboarding by building a circular test rig and running a wheel over various surfaces until the washboard surface develops.

What Mather discovered is that, contrary to what was believed at the time, washboarding is formed by the wheel bouncing along the road surface, rather than the wheel pushing a mound of material in front of the wheel then climbing over it. He also found that faster speeds produced washboarding more quickly, and there appears to be a minimum speed at which washboarding will not occur. Hard or soft tires also play a role, as does the vehicle weight and spring stiffness.

As to why different vehicles produce similar corrugations, Mather writes,

> [@](#):
>
> “It might be that the bouncing wheels even of identical vehicles should make their impacts at random points along the road. Why then should their effects be cumulative? The answer is simple: A bounce has to be triggered by something. A bump on the road that causes the wheels of one vehicle to bounce will assuredly cause the wheels of other vehicles to bounce also. The impact point following a bump will be pretty much the same for most vehicles, the angle at which their wheels ride out of the flowing hollow will be much the same, so their next impact point will be much the same and so on.”

A fascinating article that’s worth tracking down.

–Patch

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**Author:** ![John\_W.Kennedy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_w.kennedy/32/1031_2.png) [@John\_W.Kennedy](https://boards.straightdope.com/u/John_W.Kennedy)\
**Post date:** [December 24, 2003, 10:45pm UTC](https://boards.straightdope.com/t/roadway-washboarding-revisited/220871/2 "2003-12-24T22:45:16Z")

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Contratulations! You’ve managed to bring the discussion back around to what [the original article](http://www.straightdope.com/mailbag/mwashboard.html) said in the first place.

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**Author:** ![patchbunny](https://avatars.discourse-cdn.com/v4/letter/p/dc4da7/32.png) [@patchbunny](https://boards.straightdope.com/u/patchbunny)\
**Post date:** [December 25, 2003, 12:08am UTC](https://boards.straightdope.com/t/roadway-washboarding-revisited/220871/3 "2003-12-25T00:08:10Z")

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> [@](#):
>
> \*Originally posted by John W. Kennedy \*  
> \*\*Contratulations! You’ve managed to bring the discussion back around to what [the original article](http://www.straightdope.com/mailbag/mwashboard.html) said in the first place. \*\*

One does what one can. 🙂

–Patch