Wednesday, 12 September 2018

Corrugations and Snakes

A couple of reader comments have included excellent questions which I’ll endeavour to answer.


Q. What causes corrugations?

A.  Corrugations usually only occur in the surface of an unsealed road (ie, no bitumen) and no unsealed surface is perfectly smooth.  The purpose of a vehicles suspension is the make the ride smooth (springs) and keep the wheel in contact with the road (shock absorbers). 

When a vehicle is driven on the unsealed surface a slight bouncing occurs as the tyres hits the imperfect surface.  Because the tyre doesn’t continuously maintain contact with the ground when it returns to the surface the act of striking the ground removes a small part of the surface creating a tiny crater.  This tiny crater then makes subsequent tyres bounce.  As most vehicle are travelling around the same speed subsequent vehicles make the crater bigger.  Eventually this forms corrugations in the road surface giving it a “washboard” appearance.

If you drive slowly over corrugations the vehicle tends to ride up and down creating a bone jarring rattle.  Driving too fast can have a similar affect.  The aim is to find the “right speed” where the tyres skip over the tops of the corrugations avoiding the craters.

For two reasons we couldn’t do this on the Gunbarrel and Heather Highways.  The first was the damaged suspension on the trailer.  The second was because the surface had received no maintenance, meaning that in addition to the corrugations there could be huge ruts and washouts in the track.  If we had been travelling at a speed to skip over the corrugations we probably wouldn’t be able to slow down in time.

Grading an unsealed roads means the loose material is deposited back into the corrugations thus provides a smoother surface.  But its only a temporary fix requiring ongoing grading.   


OK! what do you 3 get to talk about during the driving periods?, And what precautions do you take against snakes etc whilst camping?

When driving we divided the work up.  Every hour the passenger in the backseat would replace the driver.  The driver would become the front passenger and the front passenger would move to the rear seat.  The rear passenger sat behind the driver as it’s the safest seat in the vehicle.  In a crash the driver will subconsciously attempt to save themselves which means the front passenger usually takes the brunt of the impact.  So rear passenger rests before taking on the most stressful task of driving.  The driver is responsible for controlling the vehicle and selecting the route through the tracks (there were up to four parallel tracks in places).  The driver also looks for washout, ruts and animals.  He/She is also responsible for monitoring the vehicle instruments.  The front passenger monitors the gps (we had two) and assists the driver by identifying potential hazards.  The navigator and rear passenger might chat but the driver had to remain focussed on the driving.

Yes, Australia has the six most deadly snakes in the world.  Moreover we are travelling at the end of winter when the snakes are coming out of hibernation and are both very hungry and aggressive.   The good news is humans aren’t part of a snakes diet.  They will usually only bite a human if surprised or disturbed.  Snakes don’t have ears, they sense movement by vibration through the ground.  Snakes usually eat small animals.  An example might be a rat.  Rats can be found around rubbish.  Therefore don’t drop any rubbish and you won’t attract snakes.  Makes plenty of noise when walking in the bush.  Most snakes will flee (you’re too big to eat!).  Wear long trousers and ankle boots.  Most snake bites are below the knee.  I always carry a compression bandage which can be applied if bitten by a snake.  If you do get bitten identify the snake to ensure you get the correct anti-venom delivered.  Use the satellite phone to call for help and request the anti-venom be air dropped to you urgently. 

Do a reconnaissance of your campsite before entering the location with your vehicle.  You want the ground to be smooth, firm and clear of vegetation.  Make sure there are no termites or ants otherwise you’re in for an unpleasant night!  Site your toilet location away from the campsite.  Burn or bury used toilet paper.  The paper takes decades to degrade.  Pack up everything immediately you have finished with it so in an emergency you can move in a hurry (eg, bushfire).  As previously mentioned; don’t drop rubbish.  We carried a zipped up ‘dirt bag’ on the rear of the trailer for our rubbish.  The rule is “Leave footprints.  Take photos!”

1 comment :

Mike Griffin said...

Thanks for the explanations.....have found some good maps on Google which cover your journey, and adds a new dimension to the narrative. News to-day of a record breaking gold nugget find near Kambalda makes one wonder if Mr Lasseter made a similar find and was not telling 'porkies'.
Looking forward to the next installments.