Rain driving: how to survive

South Africa's winter rainfall areas have had their fair share of heavy downpours, and the rain is set to shift to the summer rainfall areas at any time. With rain comes increased crashes and we've found South African drivers to be quite fatalistic about the risk. Some people even say South Africans forget how to drive in the wet, but if you have the right approach, your crash risk need not be much different than in the dry.

The main problem is reduced traction: a wet road might only have half as much grip as when it's dry, and any vehicle problems or driver errors are magnified on wet roads. So make sure your vehicle's shock absorbers are in good condition and the wheel alignment is correctly set. In the dry, your vehicle has so much traction that even with poor shocks and alignment which is badly out, you might still have enough breathing space to escape an emergency. Not so in the wet - the limits of adhesion are often very close to your everyday expectations. If you need to suddenly brake or swerve, any vehicle deficiencies may be enough to tip the balance of control away from you.

Don't rely on stability control or ABS brakes to get you out of trouble either. They provide control capabilities similar to those of a skid control expert, but they don't change the laws of physics. In wet weather, your vehicle's limits are closer than you think, and if you push too hard, not even sophisticated electronics may be enough to prevent loss of control.

It's nearly impossible to stay safe without visibility - how often haven't you seen drivers helplessly trying to clear a patch on a fogged windscreen, or feeling their way through heavy rain with failed windscreen wipers. If your heater, demister or wipers are deficient in any way, get them seen to now, before it's too late.

One of the main dangers in the wet is when the tread on the tyres is no longer able to channel away water, and the tyre lifts off the road surface and starts to skim across the water like a speedboat. This 'aquaplaning', as it's called, can happen at slow speeds with little water on the road if your tyres are badly worn. But with enough water on the road, even new tyres will aquaplane, and at lower speeds than you might expect.

If your vehicle's front wheels aquaplane in a corner, your steering will stop working until the vehicle encounters a drier patch or sheds excess speed, which may or may not happen in time for you to avoid hitting something. The only cure for aquaplaning is prevention: reduce speed on wet roads, especially if they appear waterlogged. It is common to see drivers continuing to drive at or above the freeway speed limit where conditions are clearly unsafe for such speeds - an unexpectedly deep patch of water may be all it takes for the vehicle to be pitched into the barriers or run wide into oncoming traffic.

Apart from keeping a safe speed for the conditions, you will also need safe following distance. Wet or dry, the human reaction time is about one second, so if you follow closer than that, you have no chance of avoiding an emergency. At urban speeds, it's easy to keep a big enough gap to stop if the vehicle ahead of you unexpectedly stops. A three to four second gap at 60 km/h will almost always enable you to react and stop on a dry road. Extend that to five or six seconds on a wet road.

But at higher speeds, everything changes. To react and stop from 120km/h requires upwards of ten seconds on a wet road. Even a minimal gap to allow for reaction and swerving time should be at least five or six seconds at 120km/h - anything less than that, and you'll either hit what's in your way or be forced into swerving so suddenly that not even the stability control electronics can control the resulting skid.

Surviving wet roads requires, more than anything, respect for what you're up against. With traction and visibility reduced, it only takes a minor error to have major consequences.

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