Rain after a dry spell, spilt oil, mud from farm vehicles and loose gravel can all make a normal road slippery. The K53 test covers this through the slippery road warning sign and the rule that you must leave a bigger gap in bad conditions.
The slippery road sign (W333)
W333, or TW333 when it is temporary, shows a car with skid marks. It warns about unusually slippery conditions on the road ahead. The action from the manual: slow down, because sudden braking or harsh steering could make your vehicle skid sooner than usual, for the next 2 km.
The sign is sometimes used with a plate such as ‘when wet’, and electronic message boards can show the same symbol together with a lower speed limit.
What makes a road slippery
- The first rain after a dry period, which lifts oil and rubber off the surface.
- Diesel or oil spills, often near intersections, filling stations and on bends.
- Mud and gravel carried onto a tar road.
- Painted road markings and metal covers, which lose grip faster than tar when wet.
Driving on a slippery surface
- Slow down before the hazard, not on it. Do your braking while the car is travelling straight.
- Be smooth. Accelerate, brake and steer gently. Sudden movements are what break the tyres’ grip.
- Leave a bigger gap. The road rules require you to increase your following distance in rain, on a slippery surface and in poor visibility.
- Check your tyres. The tread must be at least 1 millimetre deep across the whole tyre. Worn tyres clear far less water.
If the car starts to slide
Ease off the accelerator, look at where you want to go and steer smoothly in that direction. Avoid stamping on the brake. Most skids happen because the car was going too fast for the conditions, so the real fix is the first rule: slow down early.
Test yourself
These questions come from the K53TestsOnline question bank. Choose an answer to see if you are right.
Under adverse conditions such as rain, slippery road surface, poor visibility or when being followed too closely, the driver/rider of a vehicle shall
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