Corrugations

Submitted: Saturday, Dec 22, 2018 at 10:24
ThreadID: 137582 Views:4652 Replies:18 FollowUps:31
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I recently wrote an article about corrugations, the causes of and how to drive them. On my Facebook page this elicited many comments and pros and cons as one would expect. I’m not sure if I’m permitted to link to the page so wont.

One person made the comment:

‘Keith B. Mather from the University of Melbourne, way back in 1962, did the research and experiments that finally gave the real answer to the formations of corrugations.’

If anyone has a copy of Mather’s report I would dearly like to have a copy.

My article is attached. Your thoughts would be appreciated.


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Reply By: Frank P (NSW) - Saturday, Dec 22, 2018 at 11:03

Saturday, Dec 22, 2018 at 11:03
Great article, Phil.

The only thoughts that I can offer pretty much reflect the title of your article - Bloody Corrugations! LOL

I did a little research and found that Mather's findings were published in the Jan 1963 edition of Scientific American. You will have to pay a small fee to get the article.

I found some other links:
Dr Karl. Other Dr Karl writings here and here.
Some search results

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Follow Up By: Phil B (WA) - Saturday, Dec 22, 2018 at 13:44

Saturday, Dec 22, 2018 at 13:44
Thanks Frank article site, I'll chase that up.

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Reply By: RMD - Saturday, Dec 22, 2018 at 11:29

Saturday, Dec 22, 2018 at 11:29
It isn’t weight related but suspension and relatively small wheel size related which causes corrugations. Softer tyre pressures minimizes the hammering and compacting ground displacement which causes corrugations. Not sure some of the article items are related to corrugations.
Old horse and cart steel bands didn't really create corrugations and it is far better to have your foot under a tyre than a cart wheel, ie pressure is more under cart thin band.
If you speed over the ground, the effective pressure delivered to the ground is less. Only under some areas do rally cars cause undulations where they dig in.
Like high airspeed in a venturi. Slower speed, means the tyre has time to squirm and as it is forced against the road surface it effectively machines some off the road surface due to tyre that tyre squirm which is happening when maximum pressure of contact is occuring. Bald tyres would have far less effect because of no tread squirm. New, big lug tyres which squirm under pressure means more development of corrugations as a result. Tyres, as we all know, do flick out stones from the tread, it must be happening at a smaller level under the moving tread. This is made more so with the action of suspension as it's rebound energy is delivered onto the road surface. Less speed, less energy under tread to be dissipated.
Most suspensions widthdraw the tyre rearwards under compression and therefore forward and harder hitting against any slight rise in surface if it coincides with the down movement.
HQ Holdens had a front suspension which, when compressed took the tyre foward be design. They soaked up bumps and corrugations better than most. I drove on eon back roads for thousands of KMs. It worked.
Less tyre pressure means less cause speed of driving and not as severe development of corrugations. Might be more comfort on the road but the tyre is certainly squirming as it is the primary suspension of a vehicle so may not be reducing the formation of corrugations as people think it does. Less force to the road is the thing which will have the positive effect.
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Follow Up By: Phil B (WA) - Sunday, Dec 23, 2018 at 10:50

Sunday, Dec 23, 2018 at 10:50
Wow, some deep stuff there RMD, thanks.

At the end of the day i.e. suspension compression, tyre squirm, rebound energy etc, I find it’s a more comfortable ride with reduced tyre pressures and speed.

There are probably 100 more factors involved such as: time of day, wet or dry sand, sand particle sizes, wheel track, tyre compound, wheel spin … that are involved.

Years ago I read a book Wheel Tracks by W.W. Ammon. He was a bullock driver and had converted to a single geared truck. With the truck he noticed the appearance of corrugations; he put that down to being able to drive faster. He had solid rubber tyres so couldn’t let them down.


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Reply By: rocco2010 - Saturday, Dec 22, 2018 at 12:30

Saturday, Dec 22, 2018 at 12:30
We were talking corrugatioms around the fire one night on the Gunbarrel after a tough day and an old farmer in the group smiled and said “ I never had any corrigations on my farm tracks until my sons started driving.”
That would have been back in the days before any discussion of tyre pressures so he was pointing to the speed factor.
Glad to see the multiple tracks around Well 33 got a mention in your article. I was out that way a decade ago ... it’s a shocking memory. I may have cause to go back next year, not something to look forward to.

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Reply By: Member - ColnJulia - Saturday, Dec 22, 2018 at 12:30

Saturday, Dec 22, 2018 at 12:30
A good read Phil, wishing you and yours a Merry Christmas,
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Follow Up By: Phil B (WA) - Saturday, Dec 22, 2018 at 13:45

Saturday, Dec 22, 2018 at 13:45
Likewise Col, seasons greetings to you and Julia.

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Reply By: Member - John - Saturday, Dec 22, 2018 at 13:56

Saturday, Dec 22, 2018 at 13:56
Agree, "Bloody Corrugations", watched an episode of Outback Truckers and on one particularly nasty stretch of corrugations, they rigged up the spares on chains between the tug and trailer, this flattened out the corrugations some what to allow a smoother ride for the sensitive load. I have often thought about dragging a short length of chain behind both rear wheels and see if it works to break/flatten the corrugations. Will try it one day. Till then. lower tyre pressures and try and find a comfortable speed and curse those that have gone before and not lowered tyre pressures or speed.

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Follow Up By: Peter_n_Margaret - Saturday, Dec 22, 2018 at 14:40

Saturday, Dec 22, 2018 at 14:40

Cheers,
Peter
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Follow Up By: Malcom M - Monday, Dec 24, 2018 at 07:10

Monday, Dec 24, 2018 at 07:10
Some of the rangers on Cape York drag big tire carcasses behind their 4by's to keep the park tracks a bit nicer.
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Follow Up By: Candace S. - Saturday, Dec 29, 2018 at 14:05

Saturday, Dec 29, 2018 at 14:05
In my part of the world, I sometimes see "drags" constructed of old tires/tyres strapped together with steel cable and/or other hardware. I wish it were done more often!

In some areas I've visited, the authorities are quite proactive about maintaining the dirt roads they use daily. :)

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Follow Up By: Bob Y. - Qld - Saturday, Dec 29, 2018 at 18:20

Saturday, Dec 29, 2018 at 18:20
Where I work, one of the tasks is to cart gypsum into town in triple side tipper road trains, where the gypsum is refined, before being carted away by other trucks, to the east coast, Emerald & sometimes, Kununurra. With 4-6 road trains, doing 1-2 return runs per day, it doesn’t take long before some sections of the road break up into corrugations.

These sections got so bad a while back, one of the more energetic lads rigged up 2 loader tyres to tow behind his rigid tipper. Didn’t do too bad a job, but after some months I noticed both sides of the loader tyres were worn away, to be almost non-existent.

The local council does grade these roads, often once or twice a year, but it takes a safety risk on the road, before a grader is walked back to do repairs.

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Reply By: Peter_n_Margaret - Saturday, Dec 22, 2018 at 14:43

Saturday, Dec 22, 2018 at 14:43
Trains cause corrugations on railway lines.....
http://railmeasurement.com/assets/docs/090709-JRRT-corrugation.pdf
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Follow Up By: Member - John - Saturday, Dec 22, 2018 at 14:53

Saturday, Dec 22, 2018 at 14:53
Peter, what was the outcome of the towed tyres experiment? TIA.
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Follow Up By: Peter_n_Margaret - Saturday, Dec 22, 2018 at 15:06

Saturday, Dec 22, 2018 at 15:06
If done regularly it definitely improves the condition of the road.
In this case, the tyres were towed over the road section by 2 or 3 different people whenever they used it. They were left at either end for the next person to pick up as they went past, so there were no "special" trips.
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Follow Up By: Member - John - Saturday, Dec 22, 2018 at 15:27

Saturday, Dec 22, 2018 at 15:27
Peter, interesting concept. Did you ever get to the stage of not having to use the dragged tyres and if so, what happened and in what time frame? I presume other vehicles used the track in the same time period, not towing the tyres?
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Follow Up By: RMD - Saturday, Dec 22, 2018 at 16:21

Saturday, Dec 22, 2018 at 16:21
Peter_n_Margaret
Train line corrugations? Do you think that may have something to do with the rail being unsupported between the sleepers. Some trains definitely bow the line downwards.
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Follow Up By: Peter_n_Margaret - Saturday, Dec 22, 2018 at 21:39

Saturday, Dec 22, 2018 at 21:39
95% of the traffic was not dragging the tyres, but the road was much better than others nearby.

Don't know anything about rail corrugations except that it is a common known phenomena. Google shows several in depth reports about it. They grind then to reduce the effect which I think is most common with heavy trains.

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Follow Up By: 9900Eagle - Sunday, Dec 23, 2018 at 04:47

Sunday, Dec 23, 2018 at 04:47
Tyres towed behind a vehicle do knock the tops off the corrugations and this method has been used for years by trucking contractors constantly travelling over the same stretches of road. Biggest downside is if a tyre breaks loose, it sits in the middle of the road, and it is not a vehicle friendly object for anyone else.
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Follow Up By: Les - PK Ranger - Sunday, Dec 23, 2018 at 06:15

Sunday, Dec 23, 2018 at 06:15
Another downside is any slim chance of what happened at Loretta Springs station in the NT some years ago.
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Follow Up By: Member - John - Sunday, Dec 23, 2018 at 06:54

Sunday, Dec 23, 2018 at 06:54
Les PK, please explain!
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Follow Up By: 9900Eagle - Sunday, Dec 23, 2018 at 07:35

Sunday, Dec 23, 2018 at 07:35
John from memory the owner of Lorella springs was towing a large tyre behind a 4wd and whatever chain or other item he was using snapped and came back and hit him in the head. It was a very serious accident.
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Follow Up By: HKB Electronics - Sunday, Dec 23, 2018 at 10:17

Sunday, Dec 23, 2018 at 10:17
Read similar can't remember who it was but tire got caught on tree root from memory tensioned up the towing rope or chain and whet the tire broke off the root it came back through the rear window of the car and seriously injured the driver.
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Follow Up By: Les - PK Ranger - Thursday, Dec 27, 2018 at 07:48

Thursday, Dec 27, 2018 at 07:48
Sorry LoreLLa Springs :/

Yes, sort length of chain was attached to tyre, then SNATCH strap to the vehicle.
Of course the snatch would have made the forces of this incident FAR greater.

http://www.nissanpatrol.com.au/forums/showthread.php?32191-Lorella-Springs-Snatch-strap-accident-WARNING-GRAPHIC-IMAGES
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Reply By: Member - John - Saturday, Dec 22, 2018 at 14:50

Saturday, Dec 22, 2018 at 14:50
Phil, great read, but one comment I would like to make. Your statement about corners having no corrugations, sorry mate, some of the worst corrugations I have experienced are on the corners, even finding them on otherwise corrugation free tracks. I think many will recall skating around corners after suddenly finding oneself on bad corrugations in a corner. Good luck with your thesis.
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Follow Up By: Life Member - Duncan W (WA) - Saturday, Dec 22, 2018 at 16:47

Saturday, Dec 22, 2018 at 16:47
Got to agree worst on corners as vehicles break and the accelerate away.

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Follow Up By: HKB Electronics - Saturday, Dec 22, 2018 at 17:41

Saturday, Dec 22, 2018 at 17:41
Also found plenty of corners with corrigations worse than the lead in tracks. River crossing at the bottom of a hill, bad corrigations up the hill that gradually lessen once over the hill, this tends to indicate accelerating up the hill is causing them in that case.
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Follow Up By: Frank P (NSW) - Saturday, Dec 22, 2018 at 18:05

Saturday, Dec 22, 2018 at 18:05
Yes, I agree. Hilly unsealed main roads have the worst corries on corners, eg main forest roads.
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Follow Up By: Phil B (WA) - Sunday, Dec 23, 2018 at 10:27

Sunday, Dec 23, 2018 at 10:27
I agree that some corners/bends have the worst corrugations ever, but thats on faster main/wider roads. I said:
.... when drivers are forced to slow down because of tight bends, the corrugations disappear.
I wasn't talking about 60-70 kph bends but 10-20kph bends. Sorry or not being clearer.
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Reply By: Member - shane r1 - Saturday, Dec 22, 2018 at 17:47

Saturday, Dec 22, 2018 at 17:47
I agree with the speed and tyre pressures being causes.
But also acceleration, and related to that is people not engaging 4 wheel drive to limit wheel slip.
When the wheels are slightly spinning they create the lumps
I was behind a vehicle in the Simpson that I heard on the radio was in 2wd , I could see it spinning up on the woops that were already there, making them worse
Has anyone else observed this?
Wouldn’t it be great to be able to control , say 50 vehicles along a bit of the CSR as an experiment. with pressures down , not accelerating heavily, just driving more gently,etc. I believe it would smooth out .
Same as if everyone drove sand dunes in the best technique possible they wouldn’t be whooped out either.

Ah now I see some other comments about acceleration.
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Reply By: Gbc.. - Saturday, Dec 22, 2018 at 18:32

Saturday, Dec 22, 2018 at 18:32
I know the army did a lot of research on corrugations. I don’t know if they ever published anything. I worked with an ex-major who ran me through it once. As I recall they didn’t come up with any silver bullets.
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Follow Up By: KevinE - Sunday, Dec 23, 2018 at 16:00

Sunday, Dec 23, 2018 at 16:00
Hi Gbc,

The army were primarily concerned with the damage to what they were transporting along corrugated roads & how best to package stuff for transport along those roads. Rather than causation of the corrugations.

They had a fantastic facility called the Packaging Development Centre (PDC) where they were able to simulate the effects of corrugations on vehicles carrying goods, especially tests on how packaging could prevent/minimise damage to those goods.

Like you say, I'm not sure they came up with anything that worked!
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Reply By: Mick O - Saturday, Dec 22, 2018 at 23:31

Saturday, Dec 22, 2018 at 23:31
Ahhh, just the thought of them makes me want to be back out there Phil.

Thanks for bringing the 'curse of the outback traveler' back to the forefront of my mind lol.








All the best for Xmas and the New Year mate. Be safe, be happy.

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Follow Up By: Phil B (WA) - Sunday, Dec 23, 2018 at 11:08

Sunday, Dec 23, 2018 at 11:08
Hi Mick, Thanks for the vids and obeservations. Yep you sure had some 'fun' with the escapee wheel.

And Scot, well only Scot could come up with '... may not be a big deal' when the tyre bolted for the scrub.'

Merry Christmas and Happy New Year to you and Vic.


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Reply By: Peter_n_Margaret - Sunday, Dec 23, 2018 at 10:54

Sunday, Dec 23, 2018 at 10:54
Here is an interesting study... Maybe there is a clue here?
On the Gary Junction Road in 2008 there were very few corrugations, but this small crest in the road was a notable exception. On either side, the road was free of corrugations.
Most of the traffic was locals who tend to travel quite fast in 2WD vehicles. I would guess that as they came over this small crest, the wheel spin would increase somewhat?
The corrugations that formed had a quite short wave length.


ps... this is inbetween Kiwirrikurra and Gary Junction.
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Reply By: Phil B (WA) - Sunday, Dec 23, 2018 at 11:12

Sunday, Dec 23, 2018 at 11:12
Thanks Peter for that, most of us would probably drive over these and not notice them.
More info to add to the potential causes of Cs.


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Reply By: Phil B (WA) - Sunday, Dec 23, 2018 at 11:29

Sunday, Dec 23, 2018 at 11:29
Dragging a log behind a truck to flatten out the corrugated road.

This log was on display at Tjukayirla Road House for years. It was used by the mail truck going to Warburton etc to flatten the corros. Note flattened bottom of log.


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Reply By: Member Kerry W (WA) - Sunday, Dec 23, 2018 at 14:09

Sunday, Dec 23, 2018 at 14:09
Scary as it is to wade into this debate I can only add my observations and experiences from growing up on farms and spending a lot of time on isolated tracks both sandy and gravelly and at times being the sole user of said tracks. Then getting frustrated that 2 or 3 vehicles have used the track once or twice and trashed it.
Being aware of what your tyres are doing is critical. This is very hard in modern comfortable vehicles because you become so isolated from the surface you are driving on - comfort vs contact with the outside, Driving rough old utes, tractors forklifts and trucks around on mud, sand and dirt gives you a nouse about what needs to happen beneath your wheels in order for you to keep moving and not stuff up your tracks!! You just cant do that these days in airconditioned silence running a 200kW (plus) V6/V8 with armchair worthy suspension....!!!

There has been good info so far about wheelbase, soil, etc etc so just some of my own thoughts...

To prevent or minimise corrugations
1/ The vehicle needs to be well balanced - for example an empty wagon vs empty trayback will form less corrugations with all else being equal due to the distribution of weight over the front and rear wheels - wether in 4wd or 2wd. (Uneven weight between the front and rear causes a tendency for wheel slip on the surface especially when cresting or cornering).

2/ Anything that limits wheel slip makes the most difference - using 4wd for a start - (duh), Limited slip diffs make a huge difference, difflocks on the front - especially unlockers (detroit/lokkas) help even more. (Especially on curves and winding tracks as fixed lockers will cause one wheel to turn more than the other causing tyre slip on one side and digging little holes.

3/ Open diff traybacks/utes/wagons seem to create the most havoc as they get a rock up as they gain and lose traction on opposing wheels. Rocking side to side and axle tramp are no no's.

4/ Tyre pressure!! - Lots already said about this but some conflicting forces at work but as mentioned earlier the main factor is lower pressures to improve traction and limit wheel slip/spin. Modern vehicles with lower profile tyres and carrying heavy loads cannot afford to reduce tyre pressure much anyway so again - why not blame city vehicles driving on bush roads

5/ Acceleration/Driving technique - a no brainer here but how many dont consider it? excessive acceleration allows for wheel slip - lift the foot when heading up inclines take it easy taking off and maintaining speed.
When towing heavy loads you can take a few extra seconds to crest a rise.


All this does not mean that if the perfectly configured and carefully driven vehicle drove over the same surface at the same speed it would not create corrugations due to tyre dynamics and imprefections on the road surface but there is a lot a good driver can do to minimise them.

Of course most dont care about who is following them anyway.

Ive probably forgotted some other observations but it is sunday morning and there are better things going on outside...


My two bobs worth - from personal experience ...45 odd years worth at that
Kerry W (Qld)
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Reply By: Member - Warrie (NSW) - Monday, Dec 24, 2018 at 10:20

Monday, Dec 24, 2018 at 10:20
Hi Phil, we met on the CSH in September. See pic for possibly the worst corros on the entire CSH north of Cooper Hills bore. A quick five points for my 2 bobs worth.
1. The bleeding obvious is lower pressures. If you can hear a flup-flup-flup then the rubber is working to relieve the shocks and keep them cooler. Tyres are easier to replace than shocks.
2. You have to get up to speed to match the wavelength of the ridges. Then the flupping is a nice hum and the ride is as smooth as it's going to get.
3. Drive -with caution - on the wrong side of the road so as to go up the less steep sides of the ridges . Your ride will be smoother.
4. Keep left side wheels on smoother edge of track while the right side gets hammered by corros. Then swap so right side is on smooth edge and left side takes the punishment. This gives shocks a chance to cool.
5. Allow SWMBO to get you to stop and take lots of pix. Again, more cooling time and a rest for your back. Cheers, Warrie
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Follow Up By: Phil B (WA) - Friday, Dec 28, 2018 at 08:00

Friday, Dec 28, 2018 at 08:00
Hi Warrie, I remember meeting out on CSH. You had tyre trouble on your van from memory.
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Reply By: Member - Gary R M (VIC) - Tuesday, Dec 25, 2018 at 14:37

Tuesday, Dec 25, 2018 at 14:37
Hi Phil, the attached link provides some pretty good info on the causes of corrugations.
http://www.abc.net.au/science/k2/trek/4wd/Overcor2.htm
Regards, Gary M.
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Follow Up By: Allan B (Sunshine Coast) - Tuesday, Dec 25, 2018 at 23:25

Tuesday, Dec 25, 2018 at 23:25
.
Part 1 of the above article is here.
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Follow Up By: Member - Boobook - Thursday, Dec 27, 2018 at 06:31

Thursday, Dec 27, 2018 at 06:31
Dr Karl doesn't let the facts get in the way of a good story. I have heard a lot of instances on radio where he just makes stuff up when people call in.

I wouldn't use him as a reliable reference. sadly.
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Follow Up By: RJC - Monday, Feb 11, 2019 at 22:07

Monday, Feb 11, 2019 at 22:07
Dr Karl would make a good politician - have you noticed he never answers the question he has been asked?
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Reply By: Ron N - Friday, Dec 28, 2018 at 02:05

Friday, Dec 28, 2018 at 02:05
The major cause of corrugations is an inadequate level of clay binder in the road base.
You can build roads using anywhere between 15% and 85% of either clay or sandy material.
That is, you can use between 15% sand and 85% clay, or between 85% sand and 15% clay.

Pebbles and small rocks assist in surface binding, along with the fine clay particles.
The problem is, a road built with 85% clay sets solid, and won't corrugate when dry - but it becomes greasy when wet.

On the other extreme end, a road surface built with 85% sand and 15% clay is great to drive on when wet - but it will corrugate when it dries, because there is an inadequate level of clay particles to bind the pebbles, rocks, and sand into a hard compacted surface.

As a grader and dozer driver, and road builder of more than 50 yrs experience, I can assure you the reason you run into corrugations on Outback roads is because they have never been formed up properly, nor built with the correct proportions of road base materials.

Outback roads and tracks are merely graded from the loose topsoils, that only rarely contain enough clay to bind properly.

In many areas, you can do a deep ditching cut with a grader, forming the roadside drain, and bring the deep clay to the surface to enable the clay to be mixed with the loose sand and topsoil.

By working the mixture of deep clay and sand and topsoil back and forth across the road formation, in a large windrow, you can generally produce a good blend of clay, sand, pebbles and rocks, to provide a very serviceable road surface - particularly if the soils are wet, by either recent precipitation, or by utilising a water truck.

An adequate level of moisture assists in compacting the fine particles of clay in tightly around the larger particles of sand and pebbles, thus providing a very firm surface that will resist corrugations.

Where the soil has deep levels of sand or topsoil, it is necessary to find an outside source of suitable road base material, that then has to be trucked in, to provide satisfactory material for the road surface.

As you can well envisage, this gets costly. Shire Councils spend multiple millions of dollars annually, in finding sources of gravel and other suitable road base materials, and then stockpiling them, and then loading and trucking them to the desired areas.

Naturally, if you can find a suitable source of good road base material fairly close to where it is required on the road, this cuts trucking costs.

Stockpiling road base requires both experience and skill. Many Shire employees have neither, and as a result, their choice of road base and execution of the stockpiling is poor.

Stockpiling involves bulldozing a slope, usually around between a metre and three metres deep in the selected road base material.

By doing this, the original soil profile is blended - because there is generally loose topsoil on top, then a layer of gravelly or pebbly material, and usually clay or sometimes even rock, below that.

By forming a slope of about 30 degrees, and dozing down that slope, to the level where the soil profile is becoming too clayey, or too rocky - and then lifting the dozer blade up to its full height, and pushing the blended materials up into a sizeable heap, that a front end loader can dig into, provides an excellent road base mix.

Many operators make the mistake of just pushing up soft gravelly soils, with inadequate levels of clay or rock.
This material is unsatisfactory for road base, and will corrugate rapidly, once laid.

I used to stockpile thousands and thousands of cubic metres of road base annually for local Shire Councils in the W.A. wheabelt.
You've more than likely driven on a lot of my selected gravel road base.

A very experienced old Shire foreman told me one time, that to produce good road base, "It's gotta be hard gravel. If it rips hard, it goes down hard".

What he was referring to, was that the naturally hard compacted gravel soils contained the necessary ingredients that ensured that they compacted and bound well, and provided low-maintenance gravel roads.

All that it takes to fix corrugations is the application of serious quantities of selected quality road base - and that road base has to have the correct proportions of sand, fine clay, and gravel or ironstone pebbles, or other suitable local small rocks, along with good levels of moisture, to ensure a well-bound and well-compacted mixture, that provides a solid surface very resistance to corrugating.

Cheers, Ron.
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Follow Up By: Banjo (WA) - Friday, Dec 28, 2018 at 08:52

Friday, Dec 28, 2018 at 08:52
Ron,

It's always a pleasure to read your informative writings. Thank you.
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Follow Up By: Malcom M - Saturday, Dec 29, 2018 at 17:06

Saturday, Dec 29, 2018 at 17:06
Interesting read Ron
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Reply By: Bob Y. - Qld - Sunday, Dec 30, 2018 at 18:44

Sunday, Dec 30, 2018 at 18:44
Good read, Phil, on an interesting, but also annoying occurrence.

Have seen plenty of corrugations over the years, big & rough, small but irritating. However, the most unusual I recall seeing, and driving on, were some on the Old Jim Jim road, between the Kakadu Highway and the old Cooinda Store.

These were spaced mostly about 4’ (1.2M)apart, varying in height up to 125mm, and often with an intermediate corrugation, though only on one side. Was somewhat unusual to drive on, in an 80 series, but we weren’t in a hurry.

Bob

Seen it all, Done it all.
Can't remember most of it.

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Follow Up By: RJC - Monday, Feb 11, 2019 at 23:40

Monday, Feb 11, 2019 at 23:40
Not much wheat amongst the chaff here Phil ! Plenty folk getting mixed up between what causes corrugations, to the best way to drive on them, and how to build a better road. I've spent 60 years travelling on corrugations, and had the benefit of my fathers experience before me. I've also spent a lot of time building and maintaining dirt roads. The facts are these - corrugations are caused by speed, appearing at different rates on different surfaces (I'm not surprised to read comments about them occurring in bitumen, concrete and rail lines).
The bad news is that the critical speed for corrugations is around 16klm/hr.
Corrugations are caused by virtually any size wheel. The larger diameter of truck tyres is no advantage. At the other end of the scale, I'm currently observing corrugations forming behind one driver in a golf cart, who on this particular stretch of road travels predominately at between 15<20 klm/h.
The wheel slip/bounce theories are just that - if you set your mind on the characteristics of corrugations you'll find a number of contradictions that don't support the theories.
We moved onto our first family property when I was three (a year before I started driving), and were there 30 years, before moving onto our current property, which will roll over 32 years in a couple of months. We had absolutely no corrugations on the first property with a strict 16klm/h regime, and only 250 metres of faint corrugations on the current one, where the public have access, and too many of them don't know what a black 15 in a red circle means. Even then, I have not put a blade on that 250 metres for over ten years.
The current property has a greater range of soil types, and range of vehicles over them, from road trains to quad bikes. Speed limit 15, not one corrugation outside the aforementioned 250 metres.
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