| Pages:
1
2 |
Oso
Ultra Nomad
Posts: 2637
Registered: 8-29-2003
Location: on da border
Member Is Offline
Mood: wait and see
|
|
What causes washboarding?
I'm sure many of us have lost tooth fillings and various nuts, bolts etc. on washboard roads. I've often wondered how this phenomenom occurs. At
first I thought it had something to do with wind as one sometimes sees similar patterns in dunes. But then, why didn't the same thing happen on
either side of the road? I finally got concerned enough to look it up in The Straight Dope:
Dear Straight Dope:
We live in a rural area and on many of the unpaved roads a washboard effect develops. Others I've asked an explanation say it's a result of bumps
causing tires to leave the ground and then land, and erosion takes care of the rest. This answer doesn't seem to account for varying speeds, car
weights and tire sizes. The ruts seem pretty uniform in their depth and spacing--wouldn't erosion create a more haphazard effect? --mileary
SDSTAFF Hawk replies:
The phenomenon you refer to is known as "washboarding," a wave-like pattern on unpaved roads that might more aptly be called speedbump hell. As you've
observed, the ruts occur with striking regularity, belying a chaotic event like erosion.
According to Tom Pettigrew, a Forest Service engineer, the cause is an unlikely source: your car's suspension. (Well, maybe not yours specifically,
but it's not innocent in this matter, either.) A vehicle's suspension system distributes the shock and energy of road irregularities with a bouncing
rhythm called harmonic oscillation. At each downstroke, the wheels exert extra force on the road, causing the particles in the road to either pack or
displace at regular intervals. Once a pattern of ruts starts to establish itself, it becomes self-reinforcing due to what engineers call forced
oscillation. The next car hits the same irregularities in the road and bounces at the same rate, causing the pattern to become more and more defined.
Forced oscillation overcomes minor variations in oscillation rate that might otherwise arise due to differences in car weight.
Wouldn't variations in speed affect the washboard pattern? Sure, which brings us to another critical part of the feedback loop: you, the driver. Drive
too fast on a washboard road and the downstroke exerted by the car wheels may meet the road at a point where a bump is ramping upwards. You know what
that means: You bounce off the ceiling. Instinctively most drivers slow to a speed at which the downstrokes coincide with the troughs between bumps,
reinforcing the pattern.
Washboarding is inevitable in any unpaved road that sees fairly heavy traffic. The only way to avoid it is to: (a) radically redesign how automotive
suspensions are made, (b) give up suspensions altogether, or (c) keep off those dirt roads.
All my childhood I wanted to be older. Now I\'m older and this chitn sucks.
|
|
|
bajalou
Ultra Nomad
Posts: 4459
Registered: 3-11-2004
Location: South of the broder
Member Is Offline
|
|
That's why alot of Baja roads are called "4 or 40". Anything in between beats you and your vehicle to a early death.
No Bad Days
\"Never argue with an idiot. People watching may not be able to tell the difference\"
\"The trouble with doing nothing is - how do I know when I\'m done?\"
Nomad Baja Interactive map
And in the San Felipe area - check out Valle Chico area |
|
|
Bob and Susan
Elite Nomad
Posts: 8813
Registered: 8-20-2003
Location: Mulege BCS on the BAY
Member Is Offline
Mood: Full Time Residents
|
|
Oso I think....
The correct answer is:
Tires do not produce dust uniformly even on uncorrugated roads, but rather in little spurts arising from rapid bouncing of the wheels.
If the wheel moves slowly, no corrugations are formed, but instead creates a deep rut.
Distances between ruts increase with speed.
When the wheel reaches a certain critical speed, it begins to move in short hops, bounding on random irregularities of the surface.
Hitting an obstacle, even a small one, propels the wheel into the air for a certain distance.
When it lands further down the track, it sprays sand forward and to the side, thus creating the beginning of a crater.
Each time it digs itself in at a crater it has to ride out again and thus repeating the pattern.
To not create washboard roads you must let most of the air out of your tires (hard tires corrugate roads faster), and you must be willing to travel at
speeds less than ten miles per hour.
|
|
|
Bruce R Leech
Elite Nomad
Posts: 6796
Registered: 9-20-2004
Location: Ensenada formerly Mulege
Member Is Offline
Mood: A lot cooler than Mulege
|
|
they are caused by people out of beer going to fast to buy some more.
Bruce R Leech
Ensenada
 |
|
|
Mike Humfreville
Super Nomad
Posts: 1148
Registered: 8-26-2003
Member Is Offline
|
|
Great post Oso
Here's another thought:
The washboard roads I drive the most happen to also be hilly, so I'm typically going either up hill or down hill. Duh!
But here's the thought part: Typically, cars driving dirt roads downhill need less acceleration. Since 1) it is the acceleration coupled with the
harmonic oscillation that forms the washboard and 2) going downhill uses less acceleration, a significant part of the equation is removed or at least
reduced.
Since the reverse applies to going uphill, where more acceleration is required, the harmonic oscillation is increased, causing larger washboards.
As a result of all this babble I have developed what I think of as the "up the down side and down the down side" theory, which stipulates that I am
less likely to encounter major washboarding if I am going uphill and cross over to the downhill side of the road. Likewise, when travelling downhill,
I stay on my own side of the road.
This has worked well for me except during two circumstances: 1) Since everyone else is smart enough to figure this all out on their own, both sides of
the road will be equally washboarded, and 2) Oncoming tractor trailers while I'm in the wrong lane!
|
|
|
eetdrt88
Senior Nomad
Posts: 986
Registered: 2-20-2005
Location: Az/Ca/Baja
Member Is Offline
|
|
i think the correct term is...
| Quote: | Originally posted by bajalou
That's why alot of Baja roads are called "4 or 40". Anything in between beats you and your vehicle to a early death.
|
8 or 80
|
|
|
jerry
Super Nomad
Posts: 1354
Registered: 10-10-2003
Location: loreto
Member Is Offline
|
|
simple
people cause washboard ever see a goat trail with washboard?? a pristine beach?? a virgin snow withwash board? nada so everyone drive 80mph the ones
that survivewell make less waSHBOARD SIMPLE ITS BETTER THEN PAVING THE WORLD
HAVE A GOOD ONE
jerry and judi
|
|
|
eetdrt88
Senior Nomad
Posts: 986
Registered: 2-20-2005
Location: Az/Ca/Baja
Member Is Offline
|
|
pompano,it looks like youre having some fun in that photo...
you know that is not allowed
|
|
|
Sharksbaja
Elite Nomad
Posts: 5814
Registered: 9-7-2004
Location: Newport, Mulege B.C.S.
Member Is Offline
|
|
That photo obviously was shot with Kodachrome film in a Brownie camera
or maybe a bad scan
THem Texas Longhorns? Brahma?
|
|
|
David K
Honored Nomad
Posts: 64852
Registered: 8-30-2002
Location: San Diego County
Member Is Offline
Mood: Have Baja Fever
|
|
Washboards happen on GRADED ROADS... which is often termed as 'Improved Roads' (vs. unimproved or natural two tracks)! Driving down Baja in the 'old
days' was real fun, once you were south of San Quintin or north of Pozo Grande... between which was ungraded two track road (except Santa Rosalia to
Mulege, but with so little traffic, no washboarding).
Boycott Graded roads!!!
-----------------------------------------------------------------------------------------------
When I first went down the peninsula to the tip:
From near Colonet (where pavement ended southbound) to San Quintin, the road was graded and ready for pavement (in 1962)... But, no pavement came, so
the graded road became washboard Hell... The locals created parallel roads to avoid the washboard (and still do where washboards exist and terrain
permits).
The highway north from La Paz was paved to Constitucion (El Crucero then) in '61... But, so thin it was gone by '66, recessed back to near Santa
Rita... The remaining graded road north to Pozo Grande junction was washboard... The main road went through Comondu in the 60's. The new highway from
Insurgentes over to Ligui/Loreto was built in '71-'72 when pavement reached all the way to Santa Rosalia that year... and on to Guerrero Negro by
spring '73.... Poor El Arco (once the state border town on the main road) was bypassed in favor of the newer salt mine town!
South from La Paz in '66: Pavement only went 10 miles, then a new graded road went as far as San Bartolo, and almost to Los Barriles where the
remaining road to Cabo San Lucas and back around to Todos Santos was a simple unimproved dirt road. From Todos Santos back north to the new graded
road, it was a smooth graded road. By 1970, the pavement reached Cabo San Lucas!
The Baja Ca Sur road builders were much much faster than those in Norte. Perhaps because Sur was still a territory (until 1974) and didn't have state
government to mess with?
|
|
|
eetdrt88
Senior Nomad
Posts: 986
Registered: 2-20-2005
Location: Az/Ca/Baja
Member Is Offline
|
|
coco's done quite a job...
down by his place of creating some nice parallel roads at some of the real bad areas....i've gotta say that driving his "newer" roads put a very big
grin on my face
|
|
|
jrbaja
Ultra Nomad
Posts: 4863
Registered: 2-2-2003
Member Is Offline
|
|
Graded roads
have nothing to do with wahboard. Vehicles do. Neither of the arroyos to my place down south are graded. They are sandy arroyos. Which smooth out
after a rain. But, even with a minimum amount of traffic, they are washboarded within 2-3 days.
And they stay that way until the next rain.
|
|
|
David K
Honored Nomad
Posts: 64852
Registered: 8-30-2002
Location: San Diego County
Member Is Offline
Mood: Have Baja Fever
|
|
|
|
|
jrbaja
Ultra Nomad
Posts: 4863
Registered: 2-2-2003
Member Is Offline
|
|
See there DK
If you just post your sense of humor, you are never wrong about anything. It's when you pretend to know something that makes you look stupid.
|
|
|
jrbaja
Ultra Nomad
Posts: 4863
Registered: 2-2-2003
Member Is Offline
|
|
It's about what causes washboard.
And graded roads have nothing to do with it, except for scrambling the eggs.
|
|
|
David K
Honored Nomad
Posts: 64852
Registered: 8-30-2002
Location: San Diego County
Member Is Offline
Mood: Have Baja Fever
|
|
Washboard (corregated) roads are always graded (scraped, bulldozed) first... The 'jeep trails', (unimproved) simple parallel ruts, are always more
pleasurable to drive, and when they have a sand base, are very nice to drive...
My point was that graded roads are not always desireable. Not that they are the ONLY place one finds washboard conditions.
It really isn't necessary to prove your intelect by always contesting anything I say here. In fact, you very well may be proving something else.
If I am not on the ball on some information, then let's see if anyone else can spot it.
----------------------------------------------------------------------------------------------
A couple years ago, I said Pemex (government run/ price controlled gasoline distribution where no competition from the private sector is allowed) was
an example of government socialism. Roberto had a fit and said I was dead wrong... Well, after meeting the owner of a Pemex franchise and learning
more... I am all the more convinced it is pure socialism... the way the federal government controls fuel there.
In fact is is even more severe than other forms of socialism, like in Australia where at least private enterprise is allowed, but tax subsidized
competition by government run business competes with the tax paying private businesses... like transportation, medical care, etc. In Mexico, there is
no competition in gasoline production and distribution.
|
|
|
jrbaja
Ultra Nomad
Posts: 4863
Registered: 2-2-2003
Member Is Offline
|
|
Jeeeezis Dude
Is everything political with you? Who gives a rats katootie about your feelings on Pemex gas stations? Or politics?
Do you hold elections around your campfires just to keep in practise?
When I see someone post something inaccurate or wrong info, I usually say something. So do many others on here and I'm sure we expect to be called
on misinformation ourselves.
The thing is, you spending so little time here, most of your info is wrong, limited, or out of date when it comes to Baja. And there's no hiding
that with double talk.
And it seems as if your info on off roading has some limited slips as well! Maybe if you picked up the pace a little you would be doing better than
half fast
|
|
|
David K
Honored Nomad
Posts: 64852
Registered: 8-30-2002
Location: San Diego County
Member Is Offline
Mood: Have Baja Fever
|
|
Are you blind, jr? Do you look at anything on the Trip Reports forum?
I go to Baja monthly or more for camping, off roading, moteling, eating, exploring, photography, now even having dental work done...
What's more, I share my trips to Baja with you guys who are interested by posting photos and details of people, places, and things of interest to
travelers and adventure seekers...
Yet you want to get the newbies or ?? to believe that I "spend so little time here..." LOL!!!
What is it you do here on Nomad?
Complain, name call, act superior because you live (in a gringo enclave) next to Rosarito Beach... Grow bamboo to help locals create an industry,
noble but will anyone besides you get to buy direct from them?
You ask us to bring you clothes and bug spray, so you can take it to them... Well, sometimes I guess... There is still a case of repellant waiting for
you to take south (one year after you said you were).
Why are you so full of spite for me and my friends here (you name call 'chicken coupers' or something childish like that)?
We (Nomads, most I consider friends) enjoy going to Baja, we help the locals (without bragging here) in various ways, we read and post on Nomad to
keep a connection to Baja and maybe meet others who share our addiction.
WHY does that scare and bother you so much that you must be negative so often? Why can't you be the nice guy that you used to be? What has happened to
you jr?
|
|
|
Barry A.
Select Nomad
Posts: 10007
Registered: 11-30-2003
Location: Redding, Northern CA
Member Is Offline
Mood: optimistic
|
|
Washboard roads-------
Pompano explained it pretty darn well, I thought. I have always noticed that graded roads DO have more washboard than the jeep tracks that David K.
talks about, and I believe that this is caused by people driving faster on graded roads than on jeep tracks. Take everything that Pompano presents,
coupled with "speed", and you get horrible washboard. I seldom have encountered washboard on jeep tracks, except where the jeep track is very
straight, which in turn allows for speed. I concluded that speed is the main culprit, but I could be totally wrong.
|
|
|
David K
Honored Nomad
Posts: 64852
Registered: 8-30-2002
Location: San Diego County
Member Is Offline
Mood: Have Baja Fever
|
|
I think you are right Barry... I didn't say that it only exists on graded roads, but that graded roads all seem to become washboard (if the rescaped
frequently to knock down the little berms of sand/gravel).I dislike graded roads when compared to unimproved roads...
In Tim Walker's great web site www.timsbaja.com, he has a link to the scintific explanation for what causes washboarding... Oso pretty much has the same explanation: bad
suspention + speed = washboard.
I will get the link and add it here...
[Post note: I can't find it there, so I posted on Fred's asking where it might be.]
[Edited on 10-7-2005 by David K]
|
|
|
| Pages:
1
2 |
![[*]](images/xmbforum/default_icon.gif){kind=icon}
