Many drivers underestimate how much dirty windows affect visibility. A thin film of salt, fogging or dust can make oncoming headlights, low sun and rain much more dangerous than they would otherwise be.

What you need to know

  • Reduced visibility affects both reaction time and distance judgment.
  • Dirt on the inside is often just as problematic as dirt on the outside.
  • Good visibility must be in place before you start driving, not while you are already on the road.

Typical situations

SituationWhat you should doCommon mistake
Low winter sunClean the window and use the correct ventilation before setting off.Trying to compensate by leaning your head or squinting.
Rain on a dark roadMake sure the wiper blades are clean and you have enough washer fluid.Trusting old wipers that only smear the dirt around.
City driving in the darkReduce speed and pay extra attention to pedestrians and cyclists.Continuing at normal speed with half-bad visibility.

Common mistakes

  • Starting the car without removing film and haze from the windscreen.
  • Using too little washer fluid and hoping the rain will clean the glass for you.
  • Forgetting the side windows and mirrors when clearing visibility.

How to practice

Read this together with Defogging and visibility , Driving in the dark and Windscreen wipers and washers .