<span class="highlight">Corrugations</span> - what causes them?

www.abc.net.au/science/k2/trek/s315128.htm

Dr Karl has some theories

cant get technical but I reckon they are an inevitable action on a fluid surface (dirt is fluid) . While a freshly graded road is pretty flat there will be something that causes supension to hop. thios creates small humps that by there own existence gets the chain in motion creating creating corragations slowly as we know them. Once they have started they only get bigger. Braking accelerating etc all has a bit to do with it as you see where the bitumen ends and there is a bit of a drop then corragations are created for a few hundred metres afterwards - same as grids
Just a theory

Scubaroo

Have a look at this. There are many others if you do a google search using the words 'corrugations in roads' Site Link

Regards Bob

Axletramp

This question is perhaps similar to; where do flies go at night?

I believe there are many theories about both, but no conclusive proof.

I could be wrong, I don't read enough.

Tell her they aren't corregations...they are simply a road enhancement , otherwise known as Scooby's Revenge :))

I commented on the same thing about corrugations a couple of weeks ago in regard to a comment Footloose made.
I thought the wind had a lot to do with it because of the ripples (corrugations0 you see on sandhills where there is no traffic.
I did a Google and came up with the ABC site mentioned and found it made very interesting reading.
I remember a time a couple of years ago when I was doing quite a few tours out to Mungo National Park. After a few days of fairly strong wind, the 'woopies' (in my opinion, v e r y l o n g corrugations) in the road were unbelievable. This was the Top Hut road, coming in from Pooncarie. I had to slow to about 30 - 40 Kph to travel without lifting the wheels of the ground.
They were spaced at around a car length apart, and went on for quite a few hundred metres wherever there was quite a sandy section of road.
I have also experienced the same thing on the Menindee - Pooncarie Road in the Wentworth Shire, which is the red sandy section of that road.
It reminded me of going up through Finke to Chambers Pillar, but the woopies were not so extreme.
Dave

they were put there to keep the rabbits out.cheers

women with big kahoonas and braking too hard

From suspension oscillations - and different suspension/types of vehicles cause different corrugations. Modern dirtbikes produce very long corrugations which are called 'whoops' whereas older dual shock bikes produce shorter ones. Trucks make very hard edge ones because they are so rigid.

I want to know what is the best way to drive them ? Mainly from the point of saving hardware - I can take the pounding but I want the car to as well !

Fast driving on dirt roads by a heap of Dicx Heads

They're caused by vehicles suspensions when tyre pressures are too high, I call them oscillation compactions.

Deflate your tyres to a comfortable but safe pressure, you will get a more comfortable ride and cause less corrugations.

I'm talking about the tightly compacted (Annoying) corrugations here.

cheers

I have found that on the inland tracks on Fraser Island, once a couple of heros have travelled the tracks in 2WD without lowering their tyre pressures (we've all heard them bragging, went everywhere in 2WD mate!) the corrugations in the sand are much deeper and more severe. Once a few gentle folk drive a track with appropriately softer tyres and in 4WD the tracks revover. Similarly on a sandy hill, if a few have gone up there will be corrugations, once a few go down they will be smoothed out.

They are caused by the wheels pushing on the surface. In 2wd the front wheels are being pushed across the suface and the wheel is travelling slightly slower than road speed. Dirt is pushed in front of the wheel before the wheel rolls over it. The same thing happens at the back where the driven wheel is turning slightly faster than road speed. The faster you travel the greater the resistance and the greater the variation between wheel speed and road speed causing greater slip and causing them to form more.
For this reason most of what everybody has said is correct, IE corrugations are caused by;
Driving in 2wd instead of 4wd (cann't understand why anybody would have a 4x4 and drive on dirt in 2wd)
Driving to fast
Accelerating or braking hard
Having tyres too hard

Bob

Do they only occur in Oz or in other countries as well????

Hi,
I once read a book by someone who drove trucks in WA in the 1920's. He made the comment that corrugations on roads only started when balloon tyres started to replace the old narrow, and very high pressure, tyres.
This suggests that the flex in the tyre plays a part.

Phil I

Land Rovers