I like bumpy roads. Not the ones permeated with potholes big enough to break an axle or skew tires out of alignment, but the “washboard” ones that make your teeth rattle, your words vibrate and your backside tingle when you drive over them.
I like bumpy roads because they force us to slow down. Jiggling along at a clip of five to 10 miles per hour gives you license to look out the side windows once in a while, to notice not only what’s ahead of you in the future but what you’re surrounded by now. A group of physicists located at universities in Canada, France and England, however, are working on eliminating our bumpy rides. By finding out what causes washboard roads, they hope to be able to design improved vehicle suspension systems that will forever banish our slow meanderings by bus, van or car.
To find out just how washboard roads are created in the first place, the physicists filled a round cylinder with sand, started spinning it and ran a rubber wheel over the surface. Within minutes, a ripple pattern appeared when the wheel moved faster than a certain threshold speed.
It turns out that soft road materials—such as sand, snow or dirt—all have subtle, uneven surfaces. When a wheel hits a tiny point of inconsistency, it pushes some of the malleable stuff past the spot, thus creating a new uneven area. As more wheels on other cars and trucks roll over the surface, they push the bumps farther along the road, and ripples and ruts grow.
According to the researchers, the “washboard effect” is mathematically similar to skipping a stone over water. A skipping stone needs to travel faster than a specific speed in order to develop enough force to be thrown off the water’s surface. The main difference between the two is that a sand, snow or dirt surface “remembers” its shape on later passes of a wheel, amplifying the effect.
The physicists found that the way to avoid creating a bumpy road was to drive very slowly. Bumps smoothed out only when the experimental wheel traveled at less than five miles per hour.
The pace of adventure
Perhaps five miles per hour should be the average speed for adventure. One of the bumpiest roads I ever experienced was in Patagonia. I was traveling in an eight-passenger van with a small group of people, and we were very slowly jouncing along a Chilean dirt road just before sunset. There wasn’t much cause for long gazes out the windshield, since the front vista changed only in tiny increments. But the view out the side windows was constantly evolving and revealing the country. Because of our snail’s pace, we had time to decipher a huemul hidden in the trees along the roadway and to notice a sleek shadow slink through the adjacent brush—what we guessed could have been a mountain lion. I’m convinced those sightings would have evaded us at a quicker clip.
Our Argentinean guide, worried we would get bored with our long, languid journey, popped his favorite tango CD into the van’s player. Somehow I know that listening to that music wouldn’t have been the same gliding along on a slick, smooth highway. Nothing could have reflected the passion of the tango more than the bumping, rattling and grinding of teeth we were just then undergoing.
For adventures, give me a road that’s just enough of a road to get me in. But make sure it shakes me up before I get there.
Here’s to your adventures, in whatever corner of the world you find them,