A strange towing phenomenon

[craigstaiano]

On our last tour away we encountered a strange towing phenomenon that i had never experienced before and wonder if others have experienced the same.

On towing our new Lunar Lexon 530 to the south west, we we towing with no issues and perfect stability and no snaking until all of a sudden on the M42 we started snaking and had to keep slowing down.

In front of us was a full loaded car transporter. When i managed to get past, which was a little nervy with the snake, but as soon as we passed it, the snaking stopped and we had no more issues at all.

Just wonder if anyone else had experienced the same issues.

 

[dougie201]

Hi there.
Think this was caused by the truck, in other words you were in its gulf stream if you like and you may have been to close to the truck until you pulled out to pass.

Dougie.....

 

[Gafferbill]

……..you experienced wind turbulence caused by the car transporter (or any other large HGV). This upset the aerodynamics of your outfit to the detriment of its stability.
I have personally witnessed this effect cause an outfit to overturn so you should take care when in proximity of HGVs when at speed.
Best advice is to keep well back and be happy with 56mph if your outfit becomes unstable…….overtake when the HGVs speed drops usually due to an incline.

 

[NigelHutson]

Whilst I have never felt the instability to the extent that you have, it's always noticable when following either car transporters or fuel tankers (even at a safe distance). It must be to do with how they disturb the air owing to the "strange" shapes.

 

[craigstaiano]

Thanks for your comments. I only experienced this behind car transporter. Following normal HGV's i didnt have the same problems

 

[PaulRT]

Hi All
There was a previous thread on this forum a few years' ago which highlighted the large amount of turbulence and 'dirty wind' from car transporters. I recall that one contributor to that string was an ex-railwayman who recounted stories of luggage being blown over on Crewe station when a car tranporter train came through. This, as you gather, has stuck in my memory! I am always wary of car transporters, when towing, and have definitely noticed increased buffeting around them. Give them a wide berth and get passed as soon as safe to do so (or slip well back) !
Cheers
Paul

 

[602]

Hi,
Several times I have noticed my outfit gently veer towards the middle of the road ........ and then I am overtaken by a motorbike. I bet the biker feels more agrieved than I do. But no problem when being passed by, or passing, an HGV.
Mind you, when towing a 12ft Sprite Alpine with a Sunbeam Alpine 2-seater (1965 vintage) about 35 years ago, my knuckles would go white when I saw something big looming in my mirror.
602

 

[Lutz]

My experience is that car transporters travelling at speed cause the worst turbulence of all vehicles on the road.

 

[colin-yorkshire1]

im suprised the prof has not posted yet seems right up his street

anyway the reason there is more turbulence behind a car transporter than a normal HGV is because of the load.
normal HGV's punch a hole in the air that goes over and round the trailer (and the reason your van seems to move towards the HGV while being over taken) after about 25ft behind the unit all the turbulence converges and cancels it's self out so as long as the gap is maintained behind the unit it doesnot effect the van too much.
a transporter on the other hand does not punch a hole in the air because of a open trailer more over the cars carried on the trailer create a turbulence all of there own because some are loaded forwards and some backwards the air flow over them is disrupted by the next one. this creates many vortexes in all directions and does not converge behind the trailer .
so a following caravan will be pulled left by some turbulence and right by others causing a snake, small at first then worse as the snake develops the only remedy is to slow down untill the turbulence has no effect keep the distance until the transporter comes to a hill then move over as far to the right as possible in the middle lane and overtake.
incedentaly a tactic I use to good effect (as well as by some other's) when being over taken by any HGV is to move over to the right near the whiteline as the HGV approaches "this makes the driver move further over in the middle lane in order to pass, and then when the unit is level with the back of the van move left to the other white line, this creates a bigger gap between the van and the HGV and minimises the effect of turbulence on the van.

 

[craigstaiano]

Thanks for your comments, Colin.

I figured it would be something to do with disruptions to airflow but not been an expert thought i'd ask and see if anyone else had experienced similar effects

Craig

 

[ProfJohnL]

Hello Colin,

Thanks for the invitation to chat!

I have seen the thread, and found that I couldn't add any further useful or even ineteresting information.

But I like having the last word so post more if you dare

 

[RayS]

I've noticed the same thing several times. A loaded car transporter must be one of the most 'dirty' aerodynamic shapes possible so it is not surprising. It would be interesting to see one in a wind tunnel compare with a normal HGV. I suspect that rigid sided HGVs are 'cleaner' in this sense than sheet sided vehicles - if you watch these (not while driving !) you can see ripples moving across the sheeting indicating local changes of pressure i.e. turbulence.

 

[forestgump]

the multi decks of a transporter will act as a defusser and the jet streem afteer may be a bit more than a smoth box lorry.

 

[JonnyG]

"incedentaly a tactic I use to good effect (as well as by some other's) when being over taken by any HGV is to move over to the right near the whiteline as the HGV approaches "this makes the driver move further over in the middle lane in order to pass, and then when the unit is level with the back of the van move left to the other white line, this creates a bigger gap between the van and the HGV and minimises the effect of turbulence on the van."

This might sound like good advice, and indeed when I was new to caravanning, it sounded helpful. Except for one thing, you are trusting another driver to react to your movement! It doesn't always happen, how you would like to think it should, and i have seen a caravans start to snake, whilst carrying out this manoeuvre, and have also seen a caravan hit an hgv, because the HGV didn't move over and the caravan got sucked into it! Thankfully no real accident occurred.
Then there is a legality question of purposely trying to force any over taking vehicle to move over to its righthandside of its lane.by you moving around for no reason, in the case of said accident the caravan was clearly at fault moving to the right and getting sucked into the side of the lorry which didnt move from its legal line.
The only sensible thing you should do, is to move over to your own left of your lane, when you are being over taken and NOT rely on others to move over to there right.

 

[colin-yorkshire1]

caravans start to snake, whilst carrying out this manoeuvre, and have also seen a caravan hit an hgv, because the HGV didn't move over and the caravan got sucked into it! Thankfully no real accident occurred.
Then there is a legality question of purposely trying to force any over taking vehicle to move over to its righthandside of its lane.by you moving around for no reason, in the case of said accident the caravan was clearly at fault moving to the right and getting sucked into the side of the lorry which didnt move from its legal line.
The only sensible thing you should do, is to move over to your own left of your lane, when you are being over taken and NOT rely on others to move over to there right.

hi all
sorry Jonny I think you are putting the trailer before the tractor unit so to speak.
the responsiblity for a safe overtaking manouver is with the vehicle that is doing the over taking not the vehicle being over taken. any accident caused in the above situation blame would clearly be with the HGV you talk about the legal line ?? well interestingly in the above situation MY legal line is anywhere within the two white lines the one on the left and the one on the right where I choose to position my vehicle "WITHIN" them is for me to decide and no one elses any overtaking vehicle no matter what it is has a duty of care to ensure that the overtaking manouver they proceed to take is safe and can be completed successfully.
as a caravanner of many years of experience and before giving up work a HGV driver I have gained as others have some degree of road craft and confidence along the way this is not being antagonistic or agressive just a proposition of not being intimidated by large vehicles.
on many occasions have been subjected to the sway manouver carried out by some drivers of HGV's where they close up right to the back of the van then pullout last minute and overtake with as much speed and as close as they dare to induce a uncomfortable van movement "a sway" and gain some degree of pleasure doing it.
the manouver I spoke of all but illiminates the posibillity of this happening and that is all. the other thing I would comment on was " i have seen a caravans start to snake, whilst carrying out this manoeuvre" all I can say here is the outfits in question must have been unstable to begin with because a gentle drift to the right and then one to the left should have no effect on the van if it did god help anyone trying to avoid a lump of debris lying in the carrageway or avioding a obsticle in the road.

 

[Surfer]

I wonder if the OP had shock absorbers fitted on their caravan.

 

[JonnyG]

Hi Colin. Sorry but I have to disagree. As i stated the caravan drifted into the lorry, the lorry did not cross over the white line it merely did not move over to the right of its lane. Secondly, you are for no obvious reason moving over to the right to try to force a vehicle to move over whilst it is doing a legal over taking move, and you are not thinking of anybody else or the consequences. IE lorry does start to move over to the right suddenly and what about the cars in the outside lane? they see this huge vehicle starting to sway across its lane towards them? they might even have noticed a caravan in the inside lane swaying one way then the other! they might read the situation wrongly and assume something is wrong.

No the only reasonable action you should do is to move to the left, not move firstly to the right then move all the way back to the left! you argument does not hold true, as you are not merely moving right and left to avoid debris, you are trying to put distance between you and the lorry so it does not cause you any un stableness whilst it overtakes you! and its effects on you can occur as it approaches you, ie from behind so to actually move to the right, nearer to the vehicle is not as sensible as many think, and yes I have also done this for years too
But the Only sensible thing one can do is keep left, and keep your direction change down to a minimum. it only takes one incident to make keeping left the better option than firstly trying to force traffic over to their right.

 

[SteveW77]

I wonder why people are traveling at a speed where they are being overtaken by speed limited HGVs in the first place?

Steve W

 

[ProfJohnL]

Hello Steve

Each to their own.

 

[colin-yorkshire1]

and yes I have also done this for years too

"nuff said"

 

[Dustydog]

This is all bunkum.
The nearside lane, number one or the one nearest the hard shoulder is considerably wider , relatively speaking, than the centre and offside lanes.
Careful and regular observation using the mirrors will soon tell you when some big brute is closing in on you. Here you relax , get ready for the suction syndrome, and just as he enters your vortex you gently move to the nearside of your lovely wide lane, keep power on, and whoosh he's gone . No drama.
The problems arise when you don't see them coming and get caught unawares.
As an aside I tend to cruise on motorways at 56/57 mph so the only nuisance things overtaking me , now and then, are coaches and white panel vans.

 

[Surfer]

This is all bunkum.
The nearside lane, number one or the one nearest the hard shoulder is considerably wider , relatively speaking, than the centre and offside lanes.
Careful and regular observation using the mirrors will soon tell you when some big brute is closing in on you. Here you relax , get ready for the suction syndrome, and just as he enters your vortex you gently move to the nearside of your lovely wide lane, keep power on, and whoosh he's gone . No drama.
The problems arise when you don't see them coming and get caught unawares.
As an aside I tend to cruise on motorways at 56/57 mph so the only nuisance things overtaking me , now and then, are coaches and white panel vans.

We do the same and no issues. On occasions we overtake HGVs when it si safe to do so and when i cna get past them quickly without breaking the speed limit!