Driving in the Rain

The onset of the rains is a tough time for motoring. While we rejoice as the world stops looking like a spilled packet of cornflakes, the trials, troubles and dangers of wet-weather motoring are more cause for concern that celebration.

There are four special safety factors to consider when driving in the rain.

Two of them - loss of grip and reduced visibility - are pretty obvious.

Whether you are driving on tarmac or dirt, whether the road becomes slightly less grippy or downright greasy, the traction of your tyres on the road surface will be reduced. This reduces the efficiency of all your controls - acceleration, braking and cornering. More time, more distance, more margin for error or emergency, must be allowed.

Even in light rain, conditions will probably be dull, and your whole outlook - even through a good windscreen with effective wipers - will be filtered through a watery blur to some extent. Your screen and windows will be more prone to misting up, your exterior mirrors may be spattered with water droplets that reduce clarity. And the same will apply to every other driver.

A third, probably less obvious but certainly no less dangerous factor, is tension. Human beings are not naturally comfortable in the rain. Not being able to see clearly can be anything from irritating to downright nerve-wracking. The differences in driver behaviour are greater in the wet - the differences between the fast and the slow, the confident and the shy, the considerate and the brash, are all exaggerated. The normal ambient flow is disrupted.

Rain also produces temporary and unexpected hazards, like deep puddles; it makes the position and severity of potholes more difficult to judge.

In short, the combination of all these factors causes a dramatic rise in all-round tension, and tension itself is a primary road hazard. It increases aggression, it reduces concentration; precisely the opposite of the best road safety qualities. Again, allowance must be made.

The fourth main safety factor also appears to be poorly appreciated by motorists. It is the situation of people who are not in cars. Pedestrians, cyclists, motorcyclists. It is essential that drivers accord these other categories of road user extra special consideration in wet conditions.

Pedestrians are much more likely to carelessly "dash out" across a road as they rush from one shelter point to another. A few econds delay for a driver may be a nuisance; for a pedestrian it is a soaking.

Cyclists and motor cyclists will be suffering even more severely from loss of traction on a wet surface, from reduced visibility. They don't have windscreen wipers on their goggles, and will have to squint against the rain if they are bare faced. They will likely be cold, wet, distracted, in a hurry and, yes, very tense.

The guy inside a cosy car, with his wipers and heater/demister on, is the lucky one. And he should acknowledge that with special consideration for "outsiders".

The most important principle of safe driving in the wet is to be very aware of these factors. That awareness will heighten concentration, and almost automatically guide your actions towards slower and more gentle manoeuvres, bigger safety allowances, more tolerance and consideration. All very positive safety factors.

The next technique is to ensure you don't make matters any worse than the rain causes.

Reduced traction - don't drive in a manner that will require sudden acceleration, cornering or braking.

Reduced visibility - make sure your wipers and demister are in good order, and make your surrounding observation more deliberate, more careful. Double check.

Tension - make a concious effort to be relaxed and stay relaxed. And alert. No matter how crazy the traffic, or how big the jam, or how frustrating the delay is to your time schedule.

Outsiders - extend special sympathy and courtesy to them; realise they are vulnerable and be helpful.

In very heavy rain, even on a well-drained road the water literally stands on the road surface like a thick film of lubricant, and the risk of aquaplaning is high.

In this respect, speed is a key factor. In order for the tyres to maintain good contact with the road surface, in moderate to heavy rain at a speed of 100 kph your tyre treads must be able to channel away 10 litres of water per second!

If they do not channel the water away fast enough, the tyre will "ski" on the top of the water and you will have no traction at all. No steerage, no brakes. This is "aquaplaning".

The ability of your tyres to channel the water away fast enough directly depend on your speed and the depth of tread. There is a significant difference between a tyre that is brand new and one that is half worn. There is a massive difference between a half-worn tyre and a bald one.

You will find that a quite small change in speed can make a big difference to your traction. There is, after all, a quite specific "point" at which the tyre fails to clear all the water, and starts to allow the build-up of a watery wedge in front of - and then underneath - the tyre. Just a few kilometres per hour slower, and traction will be good. A few kilometres an hour faster, and traction will be non-existant. Be aware that a small change in speed can cause a big change in risk.

Experienced drivers will be able to sense this point - through a lightness of the steering wheel or through the slightest loss of straight-ahead line.

And they will not drive near this point, because if any patch of road has slightly deeper water on it, they will be on the wrong side of the danger zone. A speed of at least 20 kph, and preferably 30 kph below the marginal speed is necessary for reasonable safety.

If your car does start to aquaplane, the only way to regain traction is to take your foot off the accelerator and hold a straight course until grip is regained. Do not brake. Do not turn. Do not change down or declutch.

As with motoring skills, "clever" is not how close to the danger line you can drive, but how far away from the danger line you can stay.

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