Thread: How do corrugations form?

Originally Posted by joel0407

Not having any experience with rollers myself. I can't see that happening with the corrugations we get here in the NT. Some can be near 300mm apart and 150mm deep. That's a lot of material for the roller to be moving.

Also as said previously these compactions from the corrugations can run very deep from many heavy vehicles running over them for months upon months between grading. I doubt that a roller could compact the material as deep as the compaction from the corrugations.

Happy Days.

Correct practice (not always observed) in compacting fill is to build up in lifts of no more than about 12"/300 mm. Adequate compaction, usually expressed as 94 ASHO, is difficult to achieve in deeper lifts than 12". If soil tests show inadequate compaction the only solution is to remove the fill down to where it is adequately compacted and put it back again properly this time. Worst scenario is that once practiced in real estate "developments" on the Gold Coast. Ti-tree and paperbark swamps were pushed over and sand pumped in to create land above water level. These were given minimum compaction or just left to settle. When building applications were made sometimes years later the soil tests showed the land as unsuitable for foundations and permission was refused. Much of the pushed over vegetation had not rotted down and attempts to compact using vibratory rollers failed miserably. It was like trying to compact an inner spring mattress. The solution was to rip out the fill, dump the vegetation elsewhere, put the fill back in lifts and compact properly. This would probably cost more than the land was then worth.

Sorry guys, as I said previously, corrugations are a surface defect mainly due to use of poorly-binding basecourse materials. The corrugations do not reflect or form at depth. If you make a longitudinal trench in a corrugated road, you will not see corrugations on the bottom of the pavements layers or deeper. If you do see evidence of material displacement, you have a soft subgrade issue and this is a pavement failure, not corrugations forming at depth.

Compaction by roller is only effective at shallow depths (300-500mm max.), the deeper depths by using some serious deadweight machinery or huge vibration, which is generally not good for community relations ....

Could this be the answer to corrugated roads

Oh woody alert
Imagine going through the bottle shop in that

Originally Posted by zulu Delta 534

Its quite simple really, we see examples of it every day all around us.
Next time a young lithe 20 year old girl passes by, have a good look.
Then when I, or one of a similar mature aged person walks past, have another good look.
Notice the difference in the skin?
Those wrinkles are caused by aging.
The world is getting older too you know!
Regards
Glen

Would the corrugations be caused by old blokes braking to look at lithe girls?

Sent from my GT-P5210 using AULRO mobile app

Originally Posted by bee utey

Corrugations on the old Stuart Highway were reputed to be visible in excavation to six feet deep. There was no point in grading the road any longer, that's one reason why the new road was built away from the old one. Pounding wheels shift dirt quite a distance, sideways too. Cars try to take different lines depending on the state of the track, I do that all the time to find a smoother line. Current wheel marks may date to after the last rain.

Originally Posted by cjc_td5

Sorry guys, as I said previously, corrugations are a surface defect mainly due to use of poorly-binding basecourse materials. The corrugations do not reflect or form at depth. If you make a longitudinal trench in a corrugated road, you will not see corrugations on the bottom of the pavements layers or deeper. If you do see evidence of material displacement, you have a soft subgrade issue and this is a pavement failure, not corrugations forming at depth.

Compaction by roller is only effective at shallow depths (300-500mm max.), the deeper depths by using some serious deadweight machinery or huge vibration, which is generally not good for community relations ....

No expert here but just having a guess.

While it make sense that a roller won't have a effective compaction at anything over shallow depths. I would think that years of continual compaction from heavy vehicle could go much deeper.

I'm not saying they form below the surface but once formed in the surface the compaction from the corrugations can run deep.

Once the material is compacted in waves below the surface, no amount of surface grading is going to take that away and once the surface is graded the corrugations may form faster from the deeper compaction. Even if the road was cut back, filled and compacted 300 - 500mm, if the corrugation compaction runs deeper than that, they will form again faster than vigin ground.

Happy Days.

Someone mentioned the Anne Beadell has some of the worst corrugations anywhere. I have never been there, but lets accept that if we can.

This would be very low traffic since the 70's ?, so why corrugated? OR are they preserved since a burst of heavy traffic in the 50's and 60's ?

Originally Posted by AndyG

Someone mentioned the Anne Beadell has some of the worst corrugations anywhere. I have never been there, but lets accept that if we can.

This would be very low traffic since the 70's ?, so why corrugated? OR are they preserved since a burst of heavy traffic in the 50's and 60's ?

Because the running surface is essentially dry desert sand with no cohesive (or binding) properties what so ever. It would only take a dozen 4WDs on the track to start corrugations forming.