I keep hearing traffic reports on the radio which refer to a jam being caused by an 'overturned lorry'. There's at least one a day.
Why do they overturn with such alacrity?
Are they loaded badly so that they are top heavy or do the drivers corner at lunatic speeds?
I think we should be told.
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Are they loaded badly so that they are top heavy or do the drivers corner at lunatic speeds?
Either is possible, but I'd be interested to find out how many such incidents result from the drivers trying to take action to avoid a collision, after someone in a smaller and more nimble vehicle has either pulled out too close in front or assumed that lorries can stop as fast as they can.
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Did anyone see that video clip of the first generation being rolled just by cutting a hard left-then-right turn at 30mph? My dad had the suspension on his modified, it frightened him so much.
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Did anyone see that video clip of the first generation being rolled just by cutting a hard left-then-right turn at 30mph? My dad had the suspension on his modified, it frightened him so much.
eh?
Are you talking about the A-class? I thought they adjusted all of thsoe before selling any though?
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Take a good look at a tanker next time you pass one (or it passes you!).
Centre of gravity is way higher than most vehicles, same applies to lorries - virtually all the weight is over the wheels not inbetween.
We've all had to swerve suddenly at some point to avoid something or someone, very seldom do lorries do this and get away with it.
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The first vehicles to be stopped going over exposed bridges, viaducts etc in strong winds are high-sided vehicles.
Mind you, I remember photographs of London buses from 50 years or so ago that had been tilted over to an angle of 45 degrees and still remained upright.
No passengers on the top deck though...:-)
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Should explain that the reason was to prove how safe the buses were even at that angle - however, being stationary and tilted and moving and tilted are two different aspects....
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If you want to view a short video streaming of a modern bus undertaking such a test go to:
www.cic.cranfield.ac.uk/bus_p3.htm
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My virus checker doesn't like this at all. Proceed with caution!
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Absolutely no reason why it should do - it's a perfectly respectable website for a well known UK company...:-)
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We had a case locallya few years back where a lorry overturned on a bend next to a Renault garage and wrote off a brand new IIRC Megane on the forecourt.
The new owner had taken possession of the car two minutes before the accident...
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Well at least they couldnt say "sorry sir we cant find anything wrong with it"
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Saw a fascinating little jig from a removals lorry on the A406 a few years ago.....
He overcooked it into a left-hand bend, tipped over on to his o/s wheels, miraculously held it for a few seconds, over corrected on to just the n/s wheels, finally slid down the road on his side in a shower of sparks.
Wish I'd had a video camera.
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Our local pier, where it passes over the coastal road, has numerous advance signs and warnings about the maximum height of vehicles able to go under it.
However, in the past 14 months, three lorry drivers have ignored all these and ended up with their truck stuck under the pier's structure.
It means a blocked main bypass route, several hours' work and the releasing of all the tyres' air pressure to free them.
A similar thing happened with a double decker bus full of schoolchildren whose driver strayed completely off the proper bus route, drove under a low railway bridge and sliced the roof section off, causing injuries to many of the passengers.
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I've seen lorries which have fallen over but I've never fallen over one...:-)
More serious obserations further below.
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While we're on this, is it me or do lorries seem to catch fire alot?
Alex.
--
Dr Alex Mears
Seat Leon Cupra
If you are in a hole stop digging...unless
you are a miner.
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I presume you mean individual lorries rather than lorries in general...:-)
Otherwise I'll stay well clear of the M6....
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Ah, I should have entitled the thread 'Falling-over lorries' perhaps.
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"Individual" was referring to lorries and fires; the impression given is that virtually all lorries seem to become set alight...:-)
Lorries falling over is more accurate than Falling over lorries - even with my size 11s I'd have a job to do the latter...:-))
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stuartli - I get the impression that you're from a certain sea-side 'resort' in the North West?
It beggers believe that lorries think they can squeeze under a pier when there are sufficient warning signs....
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DieselBoy
You should join the CID - you seem to be much brighter than average...:-)
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The husband of our ex next door neighbour was killed by a ready-mix concrete lorry falling over on top of his Range Rover.
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Jokin aside you see - it is a significant problem.
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Perhaps off topic, but over the last month or so I have been held up by 3 significant motorway accidents (I don't do a lot of motorway driving ordinarily) and each has involved an overturned Range Rover (2) or Disco (1). Each had been towing and the tow-a-van trailer, horse box and caravan were all standing normally while the towing vehicle was on its side. Why would this happen? Is it some inherent instability in these vehicles? Is it because people expect these vehicles to be able to tow anything and ignore normal towing "rules" (85% etc) - horse box was a double one and caravan was a big double axle one? Didn't seem to be any other adverse conditions.
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I suppose the 4WD vehicles are already inherently less stable than a normal car, any snaking of the trailer, followed by the bad reaction of braking would mean that the trailer weight would be pushing towards a rear corner of the car, helping to push it over.
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Usually lorries overturn due to driver input whether it be their carelessness (cornering too fast etc) or sharp turns in avoidance of something. I have known of strong winds to simply blow them over. I suppose mechanical failure such as a failed suspension could also cause it.
In the case of driver carelessness that can very often be due to a new driver. Lorries, HGVs, Artics etc can be very deceptive when cornering compared to cars. Because of very stiff suspensions they corner very flat meaning there is very little discernable body roll while cornering so even when you are going faster than you should be, it doesn't feel that way. A car will exhibit body roll above the norm and possible squealing tyres to let you know you are at or nearing the limit. This doesn't happen in trucks, they just corner without drama until you pass the limit and over they go.
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This thread brought back old memories so into the archives and from my old notes of the seventies:
This used to be the bane of our lives when patrolling A.1. between Scotch Corner and Boroughbridge which had numerous Roundabouts and nearly a weekly occurrence.
Gatherley Roundabout (now Catterick North I/Change) southbound was a favourite for in addition to the Roundabout there was a downhill gradient.
One of the main reasons for lorries overturning, in addition to high winds on exposed roads and rank speeding is "Roll Resonance". This is particularly prominent at Roundabouts.
With a high load the roll frequency of a vehicle is very slow. i.e. if you pushed it over a few degrees on one side it would take several seconds to swing back. High loads act like the pendulem of a clock. It has so much weight on it that the springs cannot prevent the swing back and forth and with 20 tons aboard (under weight nevertheless) it can take 20 odd seconds to sway from one side to the other. In the same time as spent in swaying from side to side is about the same time a driver would take in turning his wheel from one lock to the other when going round a roundabout slowly. If the two speeds of movement coincide then there is nothing that will prevent the whole lot turning over. It only applies to S bend manouevres , single corners are no problem at slow speeds.
The sequence at a Roundabout is as follows:
Clear approach - pronounced roll on first turn taken long and slow.
As vehicle straightens up load sways back.
As load sways back if steering is applied at critical speed load rolls over. This is generally on the section immediately preceeding the exit off and straight on.
To avoid:
First turn sharply.
Slow right hand steering to go round Roundabout
Quick left steering movement to come off
Slow straightening up having left Roundabout.
It was said then that engineering would solve the problem. Looks as if we are still waiting.
DVD
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Now I find that very interesting. That it's not excessive speed that can cause it (ibn this case) but matching, or at least getting close, to a particular danger speed.
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I remember one occasion when I was moving house, driving an LDV Convoy packed from floor to ceiling with all my worldly goods from Reading to London. Not a lorry I'll admit, but the centre of gravity was pretty high.
The trick was to steer in short but slightly-snappy movements where possible in order to minimise the amount of time that the vehicle was being steered. Due to the inertia of the heavy load the van had hardly begun to lean by the time I was straightening up.
Naturally, where a longer turn was required there was no option but to slow down considerably.
The sideways g-force that a large vehicle will feel is largely related to 2 things; the sharpness of the turn and the speed of the vehicle. Most drivers will be able to guage how slow to take a corner of a certain sharpness. Both of these effectively control the speed at which the vehicle changes direction, the g-force being felt as a result of the momentum in the load wanting to continue travelling in the direction that it was before.
In circumstances (as described above) where there is a 2nd turn in an S formation, then there is a third force at play which is the momentum into the lean that the load carries as it straightens itself from the first corner. Effectively the vehicle is carrying the g-force from the first turn as it enters the second.
It is very possible to simply roll a lorry by turning too quickly into a sharp bend though.
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Funny that,
Last month on 2 consequtive days, artic's with French plates had managed to put their lories on their Left hand sides going round a roundaboutto the last exit for Taunton.Particular roundabout ( 3 cars width) at the end of the Ilminser bypass A303 with double carriageway leading onto the roundabout.Reason, pretty obvious to fast.
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French + Roundabout = Confused
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"The trick was to steer in short but slightly-snappy movements where possible in order to minimise the amount of time that the vehicle was being steered."
You would make an excellent "fail-safe" driver 8-). In my ambulance days, the ones I drove were fitted with a device known as a Fail-Safe that would register g-forces. If you accelerated, braked or cornered beyond a preset limit the box would sound a series of beeps. Low tones for lesser movement and sharp tones for the more severe. Low tones had 30 points and sharps were 50. Collect too many points in a month and your driver status was suspended. Drivers quickly learned how to drive around the box and one of the tecniques was to "square"-off corners. It was better to get one 50 beep from a sharp turn than a series of 30s from a longer, smoother turn.
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DVD is right. It was also discovered that the speed at which the pendulum effect is most 'annoying' was often just about the same speed as a sensible lorry driver would negotiate a series of bends. Going slower or faster through the same bends can cancel out the pendulum effect.
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