Wet roads

Wet roads reduce tyre grip, so slow down. Give yourself plenty of time and room for slowing down and stopping. Keep well back from other vehicles. On a wet road, you should allow at least double the braking distance for a dry road.

After a spell of dry weather, rain on the road can make the surface even more slippery. Take extra care, especially when cornering. Be aware that different road surfaces might affect the grip of your tyres.

Consider others

Pedestrians and cyclists can easily get drenched by passing vehicles. Look well ahead and show consideration by slowing down or giving them more room when it’s safe to do so. Also give cyclists room to pull out to avoid large puddles.

Aquaplaning

A great danger when driving at speed in very wet weather is the build-up of water between the tyre and the road surface. As a result, your vehicle actually slides forwards on a thin film of water as your tyres lose contact with the road surface. This is called aquaplaning. Even good tyres can’t grip in this situation.

A clear indication that you’re aquaplaning can be that the steering suddenly feels very light. When this happens, slow down by easing off the accelerator. Never brake or try to change direction, because when you’re aquaplaning, you’ve no control at all over steering or braking.

The higher your speed on a wet road, the more likely you are to aquaplane. You must keep your speed down and watch for water pooling on the road surface.

Even at lower speeds, if the front and rear tyres on one side of the vehicle hit a patch of deeper water, the vehicle may swerve because of the additional resistance on that side.

Spray

Another reason for keeping your speed down on wet roads is the amount of water thrown up by other vehicles.

Overtaking or being overtaken by heavy vehicles on a motorway can be an unnerving experience.

If necessary, slow down to increase the distance between you and the large vehicle, remembering to look in your mirrors before you do so.

Sometimes wipers can’t keep the windscreen clear even when working at full speed. This results in the driver being temporarily blinded to conditions ahead; you may need to slow down.

If water sprays up under the bonnet, it can stop the engine or affect the electronic controls.

Dealing with floods

When you have to pass through a flood, take your time. Stop and assess how deep the water is. Don’t just drive into it. Some roads that are likely to flood have depth gauges. Check the depth on these.

Deep water

If the water seems too deep for your vehicle, turn back and go around the flood by another road. It might take a little longer, but that’s better than finding yourself stranded.

If the water is too deep it could

• flood the exhaust, causing the engine to stop
• find its way into the air intake on some vehicles, causing serious engine damage.

Shallow water

If the water isn’t too deep, drive on slowly but be sure to keep to the shallowest part. Remember, because of the camber of the road, the water is probably deepest near the kerb and shallowest at the crown. By keeping to the shallowest part of the road, you’ll be more likely to see lifted manhole covers or other debris.

Driving through floodwater

Drive in first gear as slowly as possible but keep the engine speed high and steady by slipping the clutch.

• If the engine speed is too low, you might stall.
• If you go too fast, you could create a bow wave. Water will flood the engine and it could cut out.

Try to strike a balance.

Engines and water

Some types of diesel engine will tolerate a certain amount of water, but many modern fuel systems are electronically controlled and are, therefore, affected by water.

All petrol engines can be seriously affected by even small amounts of water being splashed onto the electrical components; these can include engine management systems, ignition systems and so on.

Crossing a ford

The depth of water at a ford varies with the weather and is usually greater in winter. There may be a depth gauge in the area. If the water isn’t too deep for your vehicle, cross using the same technique as you would for a flood.

Remember to test your brakes after you cross. There might be a notice reminding you to do so.

Don’t try to displace the water by ‘charging’ at the flood or ford.

• You could lose control.
• Your vehicle will probably stall.
• You could end up blocking the road.

Test your brakes

Water can reduce the effectiveness of your brakes, so test your brakes whenever you’ve passed through water on the road. When you’ve driven safely through, check your mirrors first and then test your brakes.

If they don’t work properly, it will help to dry them out if you apply light pressure to the brake pedal while driving along slowly. Don’t drive at normal speed until you’re sure they’re working properly.