Dust storm on a desert highway
At 14:00 a haboob-style dust storm reduces visibility on a 100 km/h desert highway to about 50 m. You are driving a loaded pickup with good tyres, low-beam headlights on, and a 3-second gap behind a lorry. Traffic in the right lane is moving at 80 km/h; some cars are still overtaking at 100 km/h. Your phone mounts on the dash and a call comes in. Ahead, the lorry's brake lights glow faintly, and you can just see a lorry tail-lift. The road is straight, dry, and has a hard shoulder. You have 40 km to your exit and no urgent reason to arrive on time. Your windscreen is dusty, the washer bottle is empty, and the dashboard shows no warning lights.
1. What speed and following distance should you choose, and why?
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The 100 km/h sign is a maximum for good conditions, not a target in a dust storm. With visibility around 50 m, you must be able to stop within roughly the distance you can see. At 80 km/h you cover about 22 m every second; a 3-second gap is about 67 m, which is already longer than your visibility, and dust lengthens reaction and braking. Reduce to about 50 km/h or less and open the gap to at least 4–5 seconds; at 50 km/h, 4 seconds is about 56 m, so 50 m visibility is still marginal. Stay in the right lane, do not overtake the 100 km/h cars, and be ready to slow further.
2. Should you use hazard lights, high beam, or answer the phone?
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Use low beam, not high beam: high beam reflects off dust and makes a bright wall. Fog lamps may help if fitted, but they do not replace low beam. Do not use hazard lights while moving as a substitute for speed reduction; they can mask your indicators and confuse other drivers. If you must stop, pull fully off the carriageway, then use hazard lights. Do not answer the phone. The call is not worth the divided attention, and a mounted phone still takes your eyes and mind off a low-visibility road. Let it ring or use voicemail after you have stopped safely.
3. Visibility falls to 20 m. What is your plan?
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At 20 m visibility, continuing at highway speed is not defensible. Reduce speed immediately and look for the next exit or a safe lay-by; a hard shoulder is a last resort, not a driving lane. If you stop on the shoulder, get fully right, switch on hazard lights, keep seatbelts on until you have checked traffic, and move passengers behind the barrier away from the carriageway. Do not stand between the car and traffic. Call 112 if you are stranded or blocking a lane. If you cannot leave the road safely, keep moving slowly to the exit rather than stopping in a live lane.