When you are driving in the rain, it isn’t just your visibility that is reduced, your ability to stop is also compromised. Your car tyres will work as hard as they can to disperse the water from the road to maintain as much grip as possible, but there is only so much they can do! In order to compensate for this reduced grip, you should also reduce the speed you are driving at, and leave a bigger gap between yourself and the driver in front.
As a basic guide, under normal driving conditions you can work out the distance you need to maintain from the car in front with the two second rule, i.e. you should not be less than two seconds behind the car in front. When the road is wet, this rule becomes the four second rule. This allows you plenty of time to avoid an accident if the vehicle in front does anything unexpected.
Aside from keeping your distance, there are other precautions you can take to reduce the risk of an accident in the rain.
Visibility is one of the biggest concerns. Even with your windscreen wipers working as well as possible, rain reduces the distance you can see. To retain as much visibility as possible you need to replace your windscreen wipers when they start to be ineffective, use a decent windscreen wash and keep your windows clean as dirty windows are more likely to mist over. If your windows do start to mist up, switch on your air conditioning, or if you don’t have that, turn the heater fan on.
Aside from visibility, the biggest problem rain causes is not water in the sky, but water on the road. It sprays upwards, pools into puddles or floods and can lead to aquaplaning. How do you deal with that? Spray can suddenly reduce your visibility to zero, but it is not usually unexpected. If there is water on the road you should leave a large gap between yourself and the car in front so that you are out of reach of any spray coming off its wheels, and if you see a large vehicle coming towards you on the other side of the road, turn your wipers on or increase their intensity in preparation.
Puddles and floods can be more than just roadblocks. If you drive through them the water can pull at your wheels causing you to swerve, and they can kick up spray reducing your visibility. If you can’t avoid driving through a deep puddle or flood, make sure you drive over the highest part of the road (usually the centre) so that the water is as shallow as possible. Drive slowly and carefully – faster driving will create a wave and risk water ingress to your car and to other vehicles. To avoid getting water in your exhaust keep your foot on the accelerator, and if the car is manual, stay in first gear and slip the clutch. When you make it through the flood, gently apply your brakes to make sure they are still working, and to dry them off.
To avoid aquaplaning you should drive slightly slower on wet roads, but if you do find yourself aquaplaning, the best thing to do is to gradually release the accelerator so that the car slows down sufficiently to allow the car tyres to regain their grip on the road. Never put the brakes on, and try not to turn the steering wheel, as that puts you at risk of losing control of your car.
To sum up, when driving in the rain you should drive more carefully than usual, slower and maintain a larger gap between the vehicle in front of you than you usually would.