what speed do you need to go to have the rumble go away at the top end of the spectrum..:-)
On Saharan dirt roads vehicle suspensions gradually beat the surface into a fairly tight wave pattern that the French call 'tole ondulee', corrugated iron. It is very uncomfortable to drive over in (say) a Land Rover or other 4wd car at low speeds, but at around 50mph or a bit more the whole thing smooths out miraculously as the car skates along the tops of the waves without hitting the troughs.
The only problem is that adhesion is then much reduced, so sudden manoeuvres become much more risky... :o)
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I know you're right Lud....... few years back i had a safari holiday in Kenya.. the driver of the minbus was doing 80km/h on a dirt track road that was unbeliveably pot holed and rutted.
I thought the dash was going to come off at one point, but the actual ride comfort was fairly serene really
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Don't suppose you did any backroad travel in Matatus Westpig? Plywood box built over the bed of a Peugeot 404 pickup, with plexiglass windows. Carried up to 14 passengers with chickens, yams, typewriters (in my case) etc., and would barrel down laterite tracks at 80 mph (not kph) in reasonable comfort, swaying soporifically from side to side.
Despite the skill and delicacy displayed by the drivers though, I sometimes break into a cold sweat at the retrospective thought of all those people and their luggage and the plywood scattered down 300 yards of red earth and dry grass...
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>On Saharan dirt roads..
>so sudden manoeuvres become much more risky... :o)
Sudden manoeuvres are indeed very risky on corrugated dirt roads, it usually results in the tyre sidewalls digging into the ruts and flipping you over. The most common causes where I lived in Namibia were swerving to avoid wildlife and front tyre blowouts which are much more common and spectacular on dirt roads.
>thought of all those people and their luggage and the plywood scattered down 300 yards of red earth
I still read the online version of The Namibian fairly regularly and it's always the same story -
"Overloaded Hi-Ace overturns leaving 8 dead and 14 injured - Transport Minister promises clampdown on unroadworthy taxis". I think Alastair Campbell must be doing lecture tours over there.
On a brighter note (and thank-you for reminding me): I used to love driving on corrugated dirt roads especially in the crossply-shod company RWD pickups. As you say, the technique is to keep enough speed to skim across the crests or you'll turn your insides to jelly. Going into corners you have to turn in gently and early then let it drift before straightening out and hitting the gas. Brilliant fun.
Kevin...
PS. My wife once grabbed an old Chrysler Valiant (it was the only auto available) from the car pool to deliver some haggis to the Country Club for that night's Burns Night celebrations. The road down to the club was badly corrugated and she didn't want to damage the poor haggis so she drove very slowly.
When she got back to the car it wouldn't start so she asked one of the managers to take a look before she called for another car. He popped the hood and pulled a few wires before declaring that he couldn't see anything wrong.
"Should the battery really be there, she asked?" pointing to an empty tray and the battery hanging from one of it's cables.
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It is very uncomfortable to drive over at low speeds, but at around 50mph or a bit more the whole thing smooths out miraculously
As I recall there was a section of road in "The Wages of Fear" where the trucks of nitroglycerine had to go fast enough over the corrugations not to set it off.
Ideal job for boy racers and chavs with 1000 watt stereo systems I would think (if in a remote area with no other inhabitants.)
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Top end speed - perhaps less noticable above 85mph, but the police have some favourite laybys on this stretch of road.
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I was amazed that after a trip down to Cornwall that 'traffic calming' speed cushions have been fitted on the A30 trunk road between Penzance and Lands End. You may expect these perhaps on minor side roads in built up areas but not in a rural location. As luck would have it I was in low slung car and did not want to pass over these and as a result had to take a significant detour to avoid them. It is kind of ironic that the detour route was via a number of small villages and single track roads as a result of these traffic calming measures it caused me to add an additional 20 or so miles to the clock.
{moved into the ongoing thread - it spent some time in the BR version of cyberspace for a couple of hours, my fault...sitting on the naughty step as we speak.}
Edited by Pugugly {P} on 17/10/2007 at 00:23
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