Fog and smoke: reduced visibility signs and when to use fog lamps

In thick fog, smoke from veld fires or a dust storm, the road ahead can disappear within a few metres. The K53 rules come down to one idea: drive at a speed that lets you stop within the distance you can actually see.

The reduced visibility sign (W354)

W354, or TW354 when it is temporary, is put up where fog or smoke is common. It warns that visibility on the road ahead may be reduced. The action from the manual: look out for fog or smoke and slow down, and watch for other slow-moving vehicles.

Which lights to use

• Headlights must be on from sunset to sunrise, and at any other time when you cannot clearly see people and vehicles 150 metres ahead. Thick fog or smoke during the day counts.
• Use dipped beam in fog. Main beam reflects off the fog and makes it harder to see.
• Fog lamps only in poor visibility. You may not drive with any fog lamp lit, except when visibility is poor because of snow, fog, mist, dust or smoke. Switch them off when visibility improves, because rear fog lamps can dazzle drivers behind you.
• Never parking lamps alone. A vehicle may not be driven with only its parking lamps on.

Speed and space

• Slow down until you can stop within the distance you can see clearly.
• Increase your following distance well beyond the normal minimum. The road rules require a bigger gap whenever visibility is poor.
• Do not follow the tail lights ahead closely just to have something to aim at.
• Expect slow and stopped vehicles, especially where W354 warns of smoke from fires.
• Do not overtake when you cannot see oncoming traffic.

Test yourself

These questions come from the K53TestsOnline question bank. Choose an answer to see if you are right.

Keep learning

• Road rules: fog lamps and other lamps
• Road rules: main and dipped beams
• Night driving: headlights, dipping and visibility
• Following distance: the two-second rule