By Shell on May 10, 2021
It can bring up oils and other contaminants onto the road surface without washing them away, creating a slick combination that can be potentially dangerous.
But at the other end of the equation is really heavy rain, which can affect visibility and reduce your car’s grip and traction. In these kinds of conditions, you’ll want to avoid heavy acceleration or braking, add some distance to the car in front and keep your speed down to give some leeway for your car’s reduced grip and traction.
All in all, when it’s raining like this, you need to be wary of two major dangers.
You've probably felt your steering go light driving through a puddle. This is hydroplaning/aquaplaning – your car's tyres not being able to displace the water fast enough and losing contact with the road surface.
A tyre that isn't in contact with the road surface cannot be accelerated, slowed or turned from its course. Hydroplaning/aquaplaning essentially takes all control of the car out of your hands and the larger the pool of standing water, the greater the danger. Tyre condition, too, plays a big part – worn-out tyres are more susceptible.
Any dip, rut or pothole that gathers water at least 2.5mm deep can lead to hydroplaning/aquaplaning, so reduce speed when encountering any standing water. If you find yourself in a hydroplaning/aquaplaning situation, don't panic or hit the brakes – ease off the accelerator and hold your steering wheel straight. When you feel control come back, gently get on the brakes.
Driving through floodwaters is one of the riskiest things you can do in a car. Even if you know the road and the water seems shallow enough to drive through, it can hide debris, downed trees and power lines or sections of road that have been washed away altogether.
There is also the very real risk that you might end up stranded with a powerless vehicle (a 15cm-depth of water is enough to stop most passenger cars) or get carried away with the water flow. Research by the University of NSW has shown that a small car can start floating in just 15cm of water moving at 3.6km/h.
Don't assume you're safe to forge ahead just because you drive a big 4WD either – the same University of NSW research showed a 2.5-tonne 4WD can be moved by 45cm of water moving at 3.6km/h.
So, the message is that water on the road should always be treated with respect. Always follow emergency warnings, and – no matter the size of your vehicle – remember to slow down and be aware of potential hazards in any event of wet weather.