Aquaplaning

Given the weather today, I thought I’d write a short piece on aquaplaning, or hydroplaning, the cause, and what to do if you’re losing control or have lost control of a car.

Aquaplaning is, in simple terms, when your tyres lose traction due to the inability of the tread to clear water from under the tyres because of a build-up of water in front of them.

Aquaplaning feels like a skid on ice, snow or mud but can be much more unnerving because it can happen on any wet road even after a rain shower has stopped. It can even happen where there are long puddles left after storms but on dry days. I’ve experienced this many years ago in a car lent to me by my girlfriends’ father. A very nice SAAB 900 Turbo, and importantly more powerful than the MGB I had at the time, not only that, it was front-wheel drive and the MG was rear-wheel drive. I came round a corner several days after the last rain and was confronted by a long deep puddle across most of the road. As I hit the water fairly fast (Yes, I was driving too fast to slow enough before hitting it) the tyres lost traction and I was immediately travelling in a straight line towards the verge on the right-hand side. Luckily for me, the aquaplane didn’t end in me crashing the car, but it was very close. Lesson learned.

So, what can you do to avoid aquaplaning? Well, there are several very obvious things, such as:

• Making sure that your tyres are in good condition.
• Making sure that your tyres are correctly inflated.
• Driving in rain at an appropriate speed.
• Keeping an extra safety distance from vehicles in front of you.

There are some more advanced things too:

• Keeping a good distance from the vehicle in front and watching to see if they suddenly brake or manoeuvre to avoid standing water.
• Being aware of the camber of the road and therefore where water will collect if it can’t run off the surface.
• Watching for run-off from embankments that may cross a road surface if the drains are blocked or overflowing.
• Keeping your escape or incident routes clear. This means not hovering alongside other vehicles, or letting them do this to you. If you need to adjust your speed to achieve this, then slow down rather than speeding up.
• Following in the tracks left through the rain by vehicles ahead of you. Their tyres will have done some of the water clearance already and it will give your tyres a better chance of gripping the tarmac.

There is a particular stretch of the M5 between Junctions 20 and 19 Northbound where even after work to fix the issue, in heavy rain, there is a run-off about 10m wide right across the carriageways. This has caused several crashes over the years and I’ve witnessed cars twitching as they’ve aquaplaned. Fortunately, I’ve not seen an incident that has ended in a crash.

How do your tyres make a difference? If you’ve ever watched Formula 1 racing, you’ll notice that most of the time, the tyres have no tread pattern at all, otherwise known as Slick tyres. This is because in dry conditions, no tread means maximum rubber in contact with the track and therefore maximum grip. However, a very small amount of rain on the track and the cars become uncontrollable on slicks and the drivers all head for the pits to have treaded tyres fitted, either intermediates of full wets. Now, this is all very well for F1, because the teams employ sophisticated weather forecasting technology with up to the minute data. Not only that, but they are only having to forecast for a tiny area, unlike when we are trying to get from A to B.

Car tyres for road use have to have a legal minimum amount of tread, and it has to cover a certain area of the tyre surface. This is for good reason, as the tread pattern is what clears water from under your tyres. The less tread there is, the less water tyres are able to clear in a given amount of time.

The first signs of aquaplaning may not be loss of control but instead a sudden increase in engine revs. You might notice a change in the engine note that signals this. If you notice this, and in modern cars, you need to be paying attention because the passenger compartment is usually very well insulated from road and engine noise, you shouldn’t panic.

Usually, almost as soon as you’ve realised you’re aquaplaning, your tyres will find grip again and although unnerving, you’ll be fine. What you absolutely must not do is brake or try to steer. Just hold the steering in the neutral position, or centrally, as this gives the tyres their best chance of regaining grip as soon as they can.

Hold this position until you feel the grip return, and then gently apply the brakes. Try to stay in a straight line while you brake. I understand if you’re on a corner this won’t be possible.

If you’ve really got yourself into trouble and the car is starting to skid sideways, unfortunately, unless you know advance skid control, the only thing to do is hold on and wait for the car to come to a halt. Again, don’t brake if you can help it, it’ll often make things worse.

I’m a huge advocate of getting yourself some skid training.