Driving tests

Driving in low visibility situations

Wherever you are in the world, you will occasionally be driving with limited visibility. A little preparation and being aware of the dangers can keep you safe in these circumstances. They will happen in both day and night, good weather and bad weather. Motorcyclists are particularly at risk as they are less visible to other motorists at the best of times.

You are likely to encounter most of the following scenarios wherever you drive.

Weather and environment-related

Spray

Spray can be an issue when following a large vehicle or a vehicle towing a trailer, and also from other vehicles coming towards you.

When following a vehicle causing a lot of spray, do not overtake it unless you can see ahead; wait for a passing lane or for the driver to pull over. Hang back slightly to minimise the amount of spray, and to give yourself extra time to stop as stopping distances are greater on wet surfaces where the friction is lower.

When there are vehicles coming towards you, you will see puddles and depressions in the road that are filled with water and you can anticipate when a vehicle might cause spray. Heavy vehicles will almost always cause some spray, so be ready with the wipers.

Keep your washer bottle filled in case the spray is dirty and you need to clean your windscreen.

Rain, ice and snow

iced-windscreenIce will form on your windscreen when you stop. Clear the whole screen by pouring cold water on it (not hot water because that could crack the windscreen), or wait for the engine to warm up enough so that you can blow warm air on the windscreen. Then scrape the loose ice off.

Torrential rain can overwhelm the wipers even on full speed. Slow down until you can see well enough. In some cases you may have to stop.

Heavy snow can reduce visibility because the large white flakes reflect light back towards you. Keep your headlights on dipped beam, and slow down because the roads will be slippery.

Fog

Dense fog can seem like driving into a wall of white. High beam headlights will be reflected straight back at you, so keep them on low beam. Turn your fog lights on (but only until you’re out of the fog) and watch out for vehicles that aren’t using their lights.

Slow down, and watch for brake lights to give you a clue what’s happening ahead – which way are they turning, for example. Don’t rely on this solely for direction, though, because they could be turning into a driveway. Pay particular attention to any signs that you see so that you don’t miss your turn-off or off-ramp (if you’re on the motorway).

Brake gently in fog as drivers behind you will have less visibility of your brake lights so will need more time to react.

When pulling out of an intersection, listen for other vehicles (it’s best to turn your radio off). When you move out, do so positively and quickly – don’t dawdle because other traffic will have less visibility to avoid you.

Smoke

While this isn’t as common as in, say, Australia where they have burn-offs and bush fires, there may be times when you have to drive through smoke. Treat it the same way as you would fog – slow down and keep your lights on dipped beam. Close your windows and turn your air vents onto recirculate. Be sure that you’re not driving into a fire that could put you in a dangerous situation.

Fogging

If the air in the car is humid, which it will be when you are breathing), a cold windscreen is the perfect place for that water to condense. Keep a cloth in the car to wipe the windows and make sure you know how to operate the demisters (both front and rear) quickly, as misting can happen in a matter of seconds under certain conditions.

Using your air conditioning speeds up the demisting. You will have two separate controls for the front and rear demisting. The rear demister is usually a set of wires embedded in the rear windscreen. An electrical current is passed through it and it heats up, evaporating the condensation.

At the front, warm air will be blown onto the screen. This air comes through the engine so if the engine is cold you will not be able to blow very hot air onto the windscreen, and therefore demisting will take longer.

There are commercial anti-misting products which you can apply to your windows to reduce fogging.

Sun strike

Sun strike occurs when the sun is low and you are driving towards it. It blinds you, and it can be worse in winter because it’s lower for longer, and tends to be at that low position when a lot of people are driving into work or home from work.

Know how to set your sun visor. Keep sunglasses handy in your vehicle. If your windscreen is dirty or scratched, sun strike will be much worse. Bear in mind that if you are driving into the sun and you use your windscreen washers to start to clear the windscreen, the water on the screen will completely blind you for a couple of seconds.

Reflections

Watch out for blinding reflections from large greenhouses through to city skyscrapers. Focus your gaze on the side of the road until the reflection has passed. Use sunglasses to minimise the glare.

Motorbike riders

Use the vents in your helmet to keep it clear of fogging. Keep the visor clean and free of scratches to reduce the effects of sun strike.

Vehicle-related

Bonnet failure

Bonnet failure is very rare because bonnets are designed with a two-stage latch – if the first stage fails, the second stage catches it. However, if your car’s nose has been damaged in a previous accident then you risk your bonnet flying up at speed. The pressure of the wind will force the bonnet back into the windscreen at speed which will most likely smash the windscreen.

You will be unable to see through the bonnet. There may be a small gap underneath the bonnet, depending on its shape. The only other way for you to stop the car safely is to look out the side window  to judge where you are, and bring the car to a smooth but quick stop, ensuring not to endanger other drivers behind you.

Smashed windscreen

If a stone simply cracks your windscreen, in most cases you will be fine to drive it to a glass repair shop. However, if your visibility is compromised, then you must pull over and have your car towed to be repaired.

High-beam headlights

If a driver driving towards you forgets to dip his headlights, give a quick flash on yours to remind him. If this doesn’t work, focus your gaze on the left hand side of the road as this will be the easiest place to allow you to judge your road position without staring into the full stream of light from the full beams.

Don’t put your full beams on to ‘punish’ the other driver – that just means two of you are driving at speed towards one another being partially blinded.

Driver-related

Sneezing

Sneezing fits can be debilitating, and you’re more likely to have them if you are prone to hay fever. When you sneeze you close your eyes, therefore you are driving blind for a fraction of a second. At 100kph, if you close your eyes for 1/3 of a second, you have travelled 9 metres. That could be the difference between being able to stop, and hitting the back of the vehicle in front if it brakes suddenly. If you have medication, keep it easily accessible.

Eye problems

If you need to drive with one eye covered, or you have permanent monocular vision you need to have a visual field of 140 degrees and 6/12 vision in your good eye, therefore you will need an eye test to confirm this. It’s likely that you’ll have a condition on your licence requiring external rear view mirrors on both sides of your vehicle.

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Darren is a member of the Institute of Advanced Motorists and the NZ Motoring Writers' Guild

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Posted in Advice, Car, Heavy Vehicle, Motorbike
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