Safety Tips for Driving In Fog
Fog is one of the most dangerous driving conditions that can confront a driver. Technically fog is a dense wet mist that has descended rather like a cloud close to ground level.
When night conditions are cold, clear, and calm, the ground releases the heat it absorbed during the day. Fog forms when the temperature drops to the dew point (the temperature at which air is saturated), and invisible water vapour in the air condenses to form suspended water droplets known as radiation fog.
Fog also forms when warm, moist air travels over a cold surface. The moisture in the air condenses and forms advection fog, or "land fog." There is also another fog known as sea fog, which rolls in off the sea affecting some coastal areas. Fog can reduce visibility to a few hundred yards or less, creating dangerous driving conditions.
Usually dense fog lifts by late morning or early afternoon. If dense fog occurs it is safer to postpone your journey until it has cleared but if you cannot postpone your journey or if you are caught in fog, you will find the following tips useful.
- Concentrate on the road ahead.
- Slow down to a safe manageable speed to fit the conditions.
- Switch on your headlights and if visibility is less than 100 yards use front fog lights if fitted. Use only your Low Beam headlights as High Beams (blue dashboard beam) reflect the moisture off the fog making it even more difficult to see.
- Look in your rear mirror if you cannot see a vehicle behind you because of the thickness of the fog, switch on your rear fog lamps.
- In a queue of traffic in dense fog it is sometimes useful to tap your brakes in an on off motion to further light up the rear end of your car, but don't tap your brakes continuously while driving in fog as this can irritate drivers or make them nervous.
- Avoid dazzling the driver behind you by switching off your rear fog lamps. For example, if you are in a moving queue of traffic where the vehicle behind you is just a few feet away it is courteous and safe to turn off your rear fog lamps.
- When travelling on a motorway or dual carriageway, keep in the left-hand lane, this will provide you with the grass verge or hard shoulder as an escape route in an emergency.
- Watch your speedometer; fog can create a feeling of slow motion when you may actually be speeding. Speed is a major factor in fog-related crashes.
- Use your wipers and screen wash for maximum visibility and switch on your demisters if necessary. For fastest defogging, use the AC with the temperature set at 'hot'. This will also clear condensation from other windows.
- Switch off the radio and listen for traffic that you cannot see. If necessary open your window a little.
- While concentrating on the road ahead, you can use the left-hand edge of the road or pavement as a guide. Never use the centre white lines.
- Lit up street lamps can be a useful guide as they tend to follow the contour of the road.
- Drive defensively and always at a speed that will allow you to stop well within the distance you can see clearly through the fog.
- Keep a safe distance from the car in front and avoid hanging on to its rear lights. If it brakes suddenly you will be too close for comfort.
- Drive slowly and watch out for parked or stranded vehicles. While you may be able to see the vehicle ahead because of its lights, pedestrians and obstacles on the road may not be visible at even half the distance.
- Be patient, avoid passing, overtaking, changing lanes or crossing traffic.
- Do not accelerate to get away from a vehicle that is following too closely. Look for a lay-by to pull into and wait until the car passes before continuing your journey.
- Do not stop on the carriageway as you are likely to be rear ended which could start a chain reaction of collisions.
- Do not speed up suddenly, even if the fog appears to be lifting, a couple of hundred yards down the road and you could be back in the thick of it.
- Wait until you are sure the fog has cleared before you speed up to the legal speed limit for the road.
- If the fog is too dense to continue, pull completely off the road and try to position your vehicle in a protected area away from other traffic. Turn on your emergency hazard warning lights.
- If your car stalls or becomes disabled on a road or carriageway, turn your vehicle's hazard warning lights on. Do not try to push the car off the road. To avoid injury from a rear shunt and if it is safe to do so, get out of the car, move well away from the vehicle and call 999 to let the operator know of your emergency.
- Driving in fog can be stressful and can cause eye strain, take regular rest breaks, it is better to arrive home late than not at all.
Safety Tips for Driving In Fog - Tips and Advice Article No62 RoadDriver 2010
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