Caravan Rollovers

Submitted: Saturday, Dec 20, 2014 at 17:38
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I have just been informed by a travelling friend of a caravan roll over just South of Townsville near Alligator Creek this afternoon. There have also been 2 others recently on the Bruce Highway near Beerwah and another at Chevallum. I can't recall a time when I have observed (or been informed of) 3 van roll overs in 1 month. Is this a trend others have observed or merely a statistical aberration ?

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Reply By: Michael ( Moss Vale NSW) - Saturday, Dec 20, 2014 at 19:03

Saturday, Dec 20, 2014 at 19:03
I think it's just a statistic, everyone is in a hurry for some reason. I cant come at bad roads, it's failure to read road conditions. Michael
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Reply By: Ron N - Saturday, Dec 20, 2014 at 20:24

Saturday, Dec 20, 2014 at 20:24
It's called holiday season, or the season of madness on the roads.
The time when ordinary sensible people seem to leave their brains at home as soon as they get in their vehicle for a holiday trip.
Too many people in too much of a hurry, not enough checking of correct caravan loading and stability, and driving too fast for the traffic or road conditions.
Add in some driver fatigue, inadequate vehicle control skills, and some dubious caravan designs, and you have regular rollovers.
The numbers are always up at holiday times.
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Reply By: Nomadic Navara - Saturday, Dec 20, 2014 at 21:13

Saturday, Dec 20, 2014 at 21:13
I seem to be hearing of a lot more van roll overs lately. I feel that this has come about with the larger vans and the reduction of ball weights in the last few years. Manufacturers seem not to worry much about the critical speed of their products. Here are a couple of papers on the subject.

Caravan Dynamics

Caravan and Tow Vehicle Dynamics

When you read these articles you can see there is a little more to setting up a stable rig than "getting the rig to look level."
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Reply By: Life Member-Doug T NSW - Sunday, Dec 21, 2014 at 09:31

Sunday, Dec 21, 2014 at 09:31
I was asked by another website to write an article about 6 years ago, it explains a bit about about towing Vans and sharing the road with Trucks , what to do and what not to do .


What should you do when overtaking or being overtaken by a heavy vehicle.
Sound advice from a truckies point of view.

Heavy Vehicle Road Courtesy

I hope this info will be of help to those that are about to hit the road over Christmas .

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Reply By: Life Member-Doug T NSW - Sunday, Dec 21, 2014 at 09:45

Sunday, Dec 21, 2014 at 09:45
Have you seen this video from a truck on the Nullabor

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Follow Up By: Ron N - Sunday, Dec 21, 2014 at 11:37

Sunday, Dec 21, 2014 at 11:37
Doug, that's an amazing piece of video. That 'van is well built, usually they explode when they hit the deck on their side.

The video shows a classic example of poor 'van design by way of weight distribution though. The axle is dead central, the overhang behind the axle is enormous, and I'll wager the van was loaded with too much weight in the tail, acting as a huge pendulum.

All that's needed then, is speed (overtaking) to accelerate the tailwag - and once it starts whipping, there's very little you can do to control it, no matter how good your vehicle control skills are.
A tailwag nearly always ends in disaster.

The way to avoid it, is to load heavy items forward of the axle, pick a van design that has the axle/s moved rearwards from the centre (this makes only a small difference to towbar weight), and utilise heavy wall or low profile tyres on the van to reduce rim sideways movement in relation to the road.

Having a tow vehicle that is adequate weight is also pretty important. There's a lot of people towing vans that are too big for their tow vehicles.

I once saw an amazing set of caravan skid marks, back around 1981, on the downhill run to the Phillips River bridge on the South Coastal Hwy, West of Ravensthorpe.

The river is in a huge valley and the highway runs steeply downhill for about a kilometre each side of the bridge.
This set of caravan broadside skid marks started about halfway down the hill, and went back and forth across the whole width of the highway, for more than half a kilometre!

He/she managed to recover and pull out of the tailwag near the bottom of the hill, where the skid marks reduced in intensity and eventually straightened up.

I reckon there would have been a substantial change of underwear somewhere up the road, right after that performance!

Cheers, Ron.
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Follow Up By: Life Member-Doug T NSW - Sunday, Dec 21, 2014 at 11:59

Sunday, Dec 21, 2014 at 11:59
Thanks Ron, yes the Axle is in the center , also note it's a single axle , for a van of that size it should have been a tandem, and as we both know and agree set back from center, another advantage is the further back the axles are it makes reversing easier.
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Follow Up By: Frank P (NSW) - Sunday, Dec 21, 2014 at 12:03

Sunday, Dec 21, 2014 at 12:03
For those who like mathematics and physics, here's an interesting link.

You may need to change your java security in your java control panel to add the page to a whitelist.

If you use the Next and Previous buttons to access different demonstrations, each page will have to be added to the whitelist.

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Follow Up By: Frank P (NSW) - Sunday, Dec 21, 2014 at 12:15

Sunday, Dec 21, 2014 at 12:15
I hasten to add that the maths are beyond me but after reading the Collyn Rivers links that Nomadic Navara posted, playing with the parameters and moving the square block to simulate a swerving tug is interesting. Well, for me anyway :-)
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Follow Up By: Zippo - Tuesday, Dec 23, 2014 at 01:33

Tuesday, Dec 23, 2014 at 01:33
Doug, what I find interesting in that dashcam video is how ambitious the tug driver was. I'm presuming the truck was sitting on his 100 limiter, so how fast was the tug/van going? And I'd suggest the van also outweighed the tug.
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Follow Up By: Life Member-Doug T NSW - Tuesday, Dec 23, 2014 at 01:47

Tuesday, Dec 23, 2014 at 01:47
G'day Zippo
It's makes no difference as to the speed of the truck, as an ex truckie I got to learn that if they have a truck in front they have to overtake it.....regardless.

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Follow Up By: Zippo - Tuesday, Dec 23, 2014 at 12:11

Tuesday, Dec 23, 2014 at 12:11
Yes Doug, so it seems.

Having driven all sorts and sizes of vehicles over some fifty years (but only towed vans for a matter of weeks) I still hold firmly to the view that there needs to be a licence class (or endorsement) for towing vans.

And having seen some of the antics of people trying to reverse common box trailers, maybe they should be included in an endorsement.
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Follow Up By: Nomadic Navara - Tuesday, Dec 23, 2014 at 15:05

Tuesday, Dec 23, 2014 at 15:05
Back to FollowUp 1 - "The video shows a classic example of poor 'van design by way of weight distribution though. The axle is dead central, the overhang behind the axle is enormous, and I'll wager the van was loaded with too much weight in the tail, acting as a huge pendulum."

The position of the axle is not arbitrary. If you shift it back willy-nilly you will throw too much weight on the coupling. Take another look at the video and note the side windows. The size of them indicates that there is no kitchen along the side. It will be a front kitchen van. Front kitchen vans need the axle in the centre so the ball weight is within limits. This is a classic example of why you should not have large weights at the ends of the vans.

Vans with weight concentrated at the ends have lower critical speeds than those with the weight concentrated in the centre (centre kitchen.) The critical speed of the van is the speed where if you are travelling at that speed or faster you will not be able to control the van if it becomes upset. Long heavy vans may feel stable as they are hard to make snake due to the large yaw inertia of their heavy ends. These vans may feel stable but they are not really. If you are travelling above the critical speed you will be in strife if the something upsets your van. One of the problems with the large vans is no one knows what the critical speed is, no one has tested Oz vans like they have the European vans. Some suspect that the critical speed of large vans is well below the posted speed limits. This is borne out with the number of roll overs where the driver states something like "I don't know what happened, everything was travelling smoothly when suddenly things got out of hand. I don't know what happened."

That video demonstrates what happens when the critical speed is exceeded. There is no chance of holding it. Things are perfectly "stable" until something like the bow wave of a large truck upsets the rig.
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Follow Up By: Life Member-Doug T NSW - Tuesday, Dec 23, 2014 at 18:34

Tuesday, Dec 23, 2014 at 18:34
Nomadic Navara.
I see you are trying to explain all about critical speed for towing Vans , I think this link explains all about critical speeds, and when not to overtake and ...when not to overtake

LINK

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Follow Up By: Ron N - Tuesday, Dec 23, 2014 at 19:38

Tuesday, Dec 23, 2014 at 19:38
Good God, Doug! - That video reminds me of the late Thursday afternoon before the Easter Holidays, on any major highway leading out of a capital city in Australia!! [;-)

Cheers, Ron.
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Follow Up By: Member - David M (SA) - Tuesday, Dec 23, 2014 at 20:53

Tuesday, Dec 23, 2014 at 20:53
"And having seen some of the antics of people trying to reverse common box trailers, maybe they should be included in an endorsement"
Think you might find that if you can back a 6by4 trailer Ok you can back most things.
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Follow Up By: Zippo - Tuesday, Dec 23, 2014 at 21:45

Tuesday, Dec 23, 2014 at 21:45
David, I must admit to having anything from a wry smile to almost falling down LMAO at some reversing efforts I have seen. I can back caravans and trailers (box and car). My concern is those who can't, but are still allowed to drag them all over the countryside. Surely a licence test and endorsement would make for a better place for all of us.

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Follow Up By: Life Member-Doug T NSW - Tuesday, Dec 23, 2014 at 22:13

Tuesday, Dec 23, 2014 at 22:13
Yes Ron, I think you got it right mate , Easter on the Albany Hwy.

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Reply By: Ron N - Sunday, Dec 21, 2014 at 12:05

Sunday, Dec 21, 2014 at 12:05
Here's one I came across when I was driving my Mack F785 and low-loader along Gt Eastern Hwy towards Kalgoorlie, about 1974.

http://oi54.tinypic.com/2ylsnl0.jpg

About 10 or 12kms East of Merredin, this bloke, pulling about a 30' 'van with a big old V8 AMC Rambler, lost it on a downhill run and flipped the van on its side, blocking the entire hwy - for several hours, probably.

You can just see the tarped load of a fuming East-West truckie who was stuck behind the van.
He was just the first in a long line-up of vehicles, that this accident held up!

I managed to back up the hill to a truck bay and turn around, and then using my knowledge of all the wheatbelt back roads, I detoured South of the accident site via the Merredin airport road, then East, and then North back onto the Highway again, at Bodallin.

Cheers, Ron.
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Reply By: madfisher - Monday, Dec 22, 2014 at 20:51

Monday, Dec 22, 2014 at 20:51
I have also noticed vanners towing at much higher speeds ie around the 100ks mark, where as years ago 80 was the go.
I had some tail wagging happening with a new boat I brought, solution was to move the axle back 25mm, and mount the spare up near the winch post, tows like a dream now.
Cheers Pete
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