What i left out is that the vehicles travelling on the road magnify the
imperfections that exist--small gullies from water, rocks embedded in the
surface etc. Your reasoning is fine concerning the area around stop signs
and curves etc. because that's where the most force is being exerted by the
vehicle onto the road surface right? So those areas of the road will show
the washboard effect the earliest.
And most roads (that are constructed and graded properly) have a ridged
structure with the ventre of the road being the highest point. This is
obviously to make sure that rain water doesn't sit on the road and pool-up.
So water will run "downhill" from the center to the sides of the road.
Frank WJ
>
>That would be all fine & dandy, except that the most common washboard roads
>I've experienced, the water runs on the vertical plane (ie: downhill), but
>the washboards run on the horizontal plane.
>
>The most common (and logical) explanation that I've heard for washboard
>roads is that heat/cold, combined with the braking from heavy vehicles,
>combine to shift the road surface and form the washboard effect. Most
>washboard roads in my area are on hills, as a heavy truck (dump truck) goes
>down the hill and brakes, some of that weight/energy is absorbed by the
>road
>surface, causing the surface to 'bunch up' (for lack of a more technical
>term!) and causing the 'washboard'.
>
>Think about it (and the washboard roads you might travel). Stop signs and
>stop lights -- tend to have washboard just before them, new construction in
>your area? -- how long does it take for the washboard effect to appear? I
>know that in the summer time, once construction picks up in an area, the
>roads go to washboard pretty darn quick!
>
>O.K. enough time theorizing, guess we've proved that there still is no one
>definitive answer to this question!
>
>Duff
>
>
>
>-----Original Message-----
>From: Frank Johnson [mailto:frankwjohnson@hotmail.com]
>Sent: Wednesday, March 15, 2000 3:39 PM
>To: dakota-truck@buffnet.net
>Subject: Re: DML: Washboard...
>
>
>A physicist wouldn't be able to tell you the cause. But a geomorphologist
>would--that's my area of study.
>Basically it starts with water running across the road's surface making
>very
>
>small gullies. This effect is magnified by more runoff as well as more and
>more wear from cars/trucks.
>There ya go,
>
>Frank WJ
>
>
> >
> >Hey, do we have any Physicists on the list? I was wondering if anybody
> >out there knows what causes "washboard" on dirt roads?
> >
> >Dak content: It wreaks havoc on my D2K's suspension and my jaw!
> >=====
> >Nate, Ogden UT
>
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