Why you shouldn't overtake when towing

COMMENT

It’s funny how the relaxing pursuit of a vanning holiday becomes a point-to-point time trial for some caravanners. There they are, in heavy holiday traffic on the outside lane of the freeway in the tailgating conga line of vehicles swooshing past at 110km/h.

Then there are the videos of caravanners flying past a truck, only to become totally unstuck with a crash-inducing sway.

Madness.

While there are times when you can safely overtake when towing a caravan, the  risks are magnified with something so large and often unpredictable behind; less so with a more stable fifth-wheeler.

What you’re up against

We have banged on incessantly about correct caravan and vehicle weights, tyre pressures, maintenance and payload balance, but it’s worth revisiting. If you don’t have all these element in check, then you’re facing an uphill battle to overtake other traffic and not come unstuck -- literally.

A caravan like any pig trailer is inherently unbalanced. If you visualise a caravan trying to roll down the road by itself, (luckily we have safety chains and for vans over 2000kg, breakaway brakes to prevent this), as you can imagine it could go anywhere.

So if you consider that inherent instability imposed on the tow bar, you’ll realise that it doesn't take much for the tail to start wagging the dog.

Not only do you have the unstable dynamics caused by a wheel set way back on the trailer and an unsteered coupling up front, you also have a big, bluff caravan body that can act like a sail in the wind, pushing the van -- and tow vehicle around.

In short, no matter how balanced your van, no matter how many anti-sway devices you have, any caravan will always be inherently unstable.

Not to mention what road surfaces such as potholes, poorly cambered roads or narrow roads where you can easily drop a wheel into the dirt, can do to unsettle a rig.

Then you have the matter of performance -- sure, some tow vehicles like the Ram 2500 tow a heavy van like it’s not there, but for the majority when piling on the horses, they certainly don’t thrust the rig forward as they might when driving solo.

The last thing -- and often forgotten -- is that it’s all very well focussing at the front for your big overtaking manouvre, but what about what’s happening behind you?

You need correctly positioned side mirrors or towing mirrors -- and use them -- to make sure no-one else has got a very committed overtaking manouvre going on behind, and to make sure you've left enough room for whatever you’ve just overtaken, when you come back to the left lane.

We’re not suggesting that you pack up and go home, forgetting the whole towing experience, but overtaking when towing a caravan needs a whole lot of patience, practice and alertness. When towing a van it might seem that things happen relatively slowly, but they can go wrong very, very quickly.

Also read:

Why our towing laws are ridiculous

How to avoid a roll-over

Why you should tow smarter

Highway to hell

There are also the changing road conditions to consider. Multi-lane roads are seemingly the easiest place for caravanners to overtake, but then they usually have the highest speed limit and fastest traffic.

Freeways often have large cuttings that leave you subject to sway-inducing cross-winds when you exit the cutting, as well as many large trucks with their bow wave of air flowing around them, especially when they’re travelling at their maximum 100km/h.

While you don’t have to worry about cars approaching you head-on when overtaking on a multi-lane road, you have to be much more alert for fast traffic approaching from behind if you’re about to overtake.

If your vehicle doesn’t have much performance on the hills when towing, don’t be that guy in the outside lane passing a slower vehicle at 1.5km/h faster than it's travelling; better to wait until you’ve reached a level or slightly downhill gradient to pass.

When travelling down a steep freeway hill, you have the opposite problem of potentially gaining too much speed, and a rig can more easily be unsettled when travelling down such a gradient at speed. You’ve got all that weight of the van pushing the vehicle, which can lead to sway very quickly.

All being equal, a multi-lane road is the best place to safely overtake slower traffic when towing, but preferably when it's level terrain, and the traffic's not too heavy. You also need to move over as much as you can safely to the side of the road away from large vehicles so your van is less influenced by the air movement around them and therefore less subject to sway.

Two-lane terror

A two-lane highway is likely to be the type of road you’ll be on the most if you’re doing the big lap and also the most dangerous to overtake on with a caravan.

Here you need to really pick your moment, and terrain. Like a multi-lane road, it's no good trying to overtake uphill if you’re not confident you’ll have the acceleration to pass.

The size of the vehicle you’re passing also matters more on this type of road. For example, a road train will take a long time to get by.

Most often you’ll find road trains plying roads out on long, flat and straight stretches of the inland, where in good conditions you’ll be able to see any oncoming traffic well ahead of time, and allow plenty of time to pass safely.

In light, or no traffic conditions this should be a straight-forward manouvre, but it's easy to be misled by a heat haze on the road that might mask an oncoming vehicle.

Getting caught short

As for those roads in more undulating or coastal terrain with short, straight sections that you’d overtake on without hesitation when driving solo, don’t risk it when towing.

in most cases you won’t have enough acceleration and have too much rig length to get past safely. The same applies to narrow or broken-up blacktop; you’ll be very distracted by the van trying to fall off the side of the road or excessive pitching, both of which could lead to a crash.

As for dirt roads, unless the vehicle in front has slowed to 40km/h or less to let you pass, it's best not risk it with a large van. The road surface is slippery, often potholed and the dust kicked up from the vehicle ahead will make it hard to see past it.

Don't speed!

The fact is that if you’re using every bit of the speed limit or more to overtake a vehicle, especially a large one, you’re throwing in all sorts of vehicle dynamics -- and aerodynamics --you don’t have in a slower overtaking move.

The highest risk comes front the air being pushed to the sides of a large vehicle you’re overtaking, upsetting the caravan and/or inducing sway.

The seemingly no-brainer overtake move is when you have a very slow vehicle like a tractor plodding along the highway in front of you. But even then you still need space and time to overtake, much more than if you weren't towing.

Do you really need to overtake?

Let’s face it, the distance you have to cover on transport stages in the Outback can be huge, or the traffic to get through to get to the campsite on an all-too-brief weekend away can really slow you down. Both these scenarios put pressure on the driver to keep up a good average speed.

So the best overtaking advice I can give is to avoid overtaking when towing whenever possible. Either plan a longer weekend away so you have more time to travel to camp and back, or if you’re doing the big lap, plan shorter transport stages.

In the worst case scenario -- where you’ve run out of daylight in the outback and are worried about wildlife strikes, or fatigue hits -- don’t forget you can pull over and take a very short walk behind where you have accommodation perfectly set up just for you...