Caravan roll over Bruce Hwy

[BruceandBobbi]

Bruce Hwy.

https://7news.com.au/news/accidents/caravan-rollover-in-north-queensland-sparks-new-police-safety-warning-c-384034

[nj swb]

Bruce Hwy.

https://7news.com.au/news/accidents/...rning-c-384034

Wow!

Very sobering. Looking at the roofline at the end, it's a miracle the occupants had only minor injuries.

Edit: to my inexperienced eye, it looks like a big van - so I went looking for some specs. It looks very much like a Kingdom Kensington Evo; a 2012 model I found reports an ATM of 2660 kg, a 2014 model reports ATM of 2480 kg.

My google search also led to a discussion forum post that a Kingdom van actual weight came in 400 kg above claimed tare. I wonder how actual weight compared to the Gen 3's towing limit? Did the owner know what he/she was towing?

[old Jack]

Lucky escape for those involved. It could have been much worse considering the on coming traffic. Just shows how quickly it can all turn pear shape when the Laws of Physics take over.

OJ.

[2bad4u]

I haven't had my eyeballs calibrated lately, but they appeared to be travelling at a pretty good speed considering the pace at which they were overtaking the camera car.

[Ian H]

Speed, probably badly loaded with weight in the rear behind the van axles and then they hit the bow wave from the truck as they pass. There's a lot of videos on YouTube showing the same thing as they try to change lanes too soon after passing.

[Paul NT]

Whilst in Queensland in July, I had lots of big caravans pass me while I was doing 100 gps corrected. I mean, there're on holidays, why not slow down a little, enjoy the trip and get to your campsite 15 mins later, (and save a bundle of fuel) and most importantly improve your chances of arriving.

[mongoose]

Would not be surprised if the caravan was not loaded correctly.


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[dean]

We came across a 4wd and caravan today laying on its side. All emergency services were in attendance. Dunno how it happened.

[old Jack]

For those that are interested there is a book that explains it all apparently.

https://www.rvbooks.com.au/page/caravan-rollovers-why-they-happen/

OJ.

[nj swb]

For those that are interested there is a book that explains it all apparently.

https://www.rvbooks.com.au/page/caravan-rollovers-why-they-happen/

OJ.

Hmmm.

Critical speed for a (poorly configured) combination my be well below 100km/h, but one of the prevention tips is "never exceed 100 km/h (especially when overtaking)". How does a 100km/h limit help if critical speed is well below 100km/h?

Critical speed is related to the ratio between towing vehicle mass and trailer mass, yet "With almost all locally-made caravans that speed is very close (or under) 100 km/h". A blanket statement making no caveats for caravan mass or tow vehicle mass? With the right towing vehicle, any van could have a much higher critical speed. With the wrong towing vehicle, any van could have a much lower critical speed. How can "... all locally-made caravans" have a critical speed "very close (or under) 100 km/h" if the mass of the towing vehicle is so important?

An overhung tow hitch increases down forces on the rear of the towing vehicle, which is "virtually a recipe for swaying", yet inadequate tow ball mass is also bad. So I need a shorter hitch to reduce down force on the towing vehicle, but a heavier tow ball mass to increase it?

And we wonder why your average punter can't get this right? One can only hope the book itself is clearer than the advertorial.

[Greg Grey Grumbly]

I note the camera carrying vehicle being overtaken was CB radio equipped. I wonder if the overtaking vehicle was CB equipped and, whether he or she had called up the vehicle in front.

The primary reason I have a CB radio is for safety, to call up the vehicle in front if possible, first to let them know I’m coming around. If I’m being overtaken I’d call up the B Double or whoever is overtaking to acknowledge and inform them That I’ll be backing off when the overtaking vehicle is out and clear, (they are fully out in the overtaking lane) until the overtaking vehicle is well past.

That way overtaking can be done safely and well below critical speeds and both vehicles remain within their operating limits. This is standard procedure for trucks and it’s one I’ve adopted - who wants to have a caravan and tow vehicle attempting an overtake at 100kmk+.

[old Jack]

Comments in "blue font" in your post below.

Hmmm. Agree!

Critical speed for a (poorly configured) combination my be well below 100km/h, but one of the prevention tips is "never exceed 100 km/h (especially when overtaking)". How does a 100km/h limit help if critical speed is well below 100km/h?
Correct, so unless the critical speed of the vehicle and trailer combination is known, then is even 80kph a safe speed.

Critical speed is related to the ratio between towing vehicle mass and trailer mass, yet "With almost all locally-made caravans that speed is very close (or under) 100 km/h". A blanket statement making no caveats for caravan mass or tow vehicle mass? With the right towing vehicle, any van could have a much higher critical speed. With the wrong towing vehicle, any van could have a much lower critical speed. How can "... all locally-made caravans" have a critical speed "very close (or under) 100 km/h" if the mass of the towing vehicle is so important?
Correct. Not only do you need to know the weight of the tow vehicle but also the wheelbase, rear overhang length and weight distribution of the weight before and after the trailer is in hitched up.

An overhung tow hitch increases down forces on the rear of the towing vehicle, which is "virtually a recipe for swaying", yet inadequate tow ball mass is also bad. So I need a shorter hitch to reduce down force on the towing vehicle, but a heavier tow ball mass to increase it"
Close. The length of the rear overhang compared to the length of the wheelbase of the vehicle determines the leverage factor that when multipled by the towball weight is the actual mass applied to the vehicle and the effect of the change in weight distribution. All this only gives you a static calculation. To get a dynamic stability calculation you need to know the spring and dampening rates of the suspension of both the trailer and the tow vehicle, you need to know the tyre pressure and sidewall rigidity of the tyre's fitted to the vehicle and trailer, the weight distribution and load centres of the vehicle and the trailer, and the side area distribution of the trailer.

And we wonder why your average punter can't get this right? One can only hope the book itself is clearer than the advertorial.
I hope the book will be some what clearer but it cannot be specific for each vehicle and trailer setup..

You see "twitchy" trailers all the time when travelling. I look for the high frequency bounce of the trailer axle and wheels, this is caused by too high or too low tyre pressures for the tyre's fitted. Stiff non-compliant trailer suspension which puts extra dynamic loads on the tyre's. Tail wagging of the trailer is another warning sign to keep your distance. Any setup that has the vehicles rear suspension compressed so the rear mudflaps are almost scraping the road and/or the safety chains dragging on the road, ring alarm bells in my head.

Why I am so observant and concerned?
Unfortunately, when I was in my mid 20's, I was a passenger in a vehicle rollover that was towing a trailer that got a sway up at 90kph. The driver tried to accelerate out of the problem but at about 100kph the trailer jack knifed and flipped the car rolling it 3 full revolutions as the trailer coupling and safety chains failed. Fortunately the first and second revolution were in mid air and the car structure only had to take a single rollover impact on the soft road verge. We where able to walk away with minor whiplash injuries.

The 4m long flat bed aluminium, single axle leaf sprung trailer was loaded with 2x 6m long fibreglass Canadian canoes weighing about 100kg each so all up less than 750kg total but the load was long and overhung the rear of the trailer by several metres. The tow vehicle was a stock 82 Subaru 4wd wagon weighing about 1600kgs loaded with 5 people so combined with a light towball down load it was near its legal GVM and CGM limits. As no one was seriously injured there was not a detailed inquiry or report, and it was put down as just a no cause found accident in the Police report.

OJ.

[Mundy55]

Its my vague understanding, IIRC, that applying the trailer/van's brakes only, via manual activation of the brake controller, can correct the sway before it gets out of control. Is that not so?
However, watching the videos, one would have to be very alert to do it as the sway is starting because by the time the sway is in full swing (pardon the pun?) you'll be too busy just holding on to the steering wheel.

[Ian H]

Its my vague understanding, IIRC, that applying the trailer/van's brakes only, via manual activation of the brake controller, can correct the sway before it gets out of control. Is that not so?
However, watching the videos, one would have to be very alert to do it as the sway is starting because by the time the sway is in full swing (pardon the pun?) you'll be too busy just holding on to the steering wheel.

That's correct. Apply the manual brake and hopefully it will stop the sway.

Another tip is to turn the brake controller up to full if you are going to be doing 100k on a highway. The theory is that if you do happen to touch the brakes, the van will brake harder first, rather than push the tug.

[old Jack]

Its my vague understanding, IIRC, that applying the trailer/van's brakes only, via manual activation of the brake controller, can correct the sway before it gets out of control. Is that not so?
However, watching the videos, one would have to be very alert to do it as the sway is starting because by the time the sway is in full swing (pardon the pun?) you'll be too busy just holding on to the steering wheel.

Applying the trailer brakes will reduce the sway if caught early but it will also reduce the vehicle/trailer overall speed, so in an overtaking situation this could be a problem unless you have no oncoming traffic.

It is amazing how quick it all happens, you only have a few seconds before it the situation is not recoverable!

With modern technology it should be possible to fit ASC independently to a trailer, all that is required id a battery, ECU, Yaw sensor and wheel speed sensor so when a sway is detected the trailer brakes can be automatically applied and released individually on each side of the trailer to correct the imbalance. A visual and audible feedback in the cabin of the tow vehicle could give the driver warning of the ASC intervention.


OJ.