CDL General Knowledge TestDriving SafelyEasy
When driving in heavy fog, which of the following lighting techniques is best for visibility and safety?
- AUse high beam headlights to penetrate the fog.
- BDrive with no headlights on, relying on ambient light.
- CTurn on only your parking lights to avoid blinding others.
- DUse low beam headlights and, if equipped, fog lights.
Show answer & explanationAnswer & explanation
Correct answer: D. Use low beam headlights and, if equipped, fog lights.
High beam headlights reflect off fog particles, creating glare that reduces visibility. Low beam headlights are designed to illuminate the road closer to the vehicle and below the main fog layer, while fog lights are specifically designed to cut through fog close to the ground.
Why the other options are wrong
- A. High beams cause glare and worsen visibility in fog.
- B. Driving without any headlights in fog is extremely dangerous and illegal.
- C. Parking lights are insufficient for visibility in fog and are not designed for driving.
Driving in Fog Lighting
When driving in fog, use low beam headlights and, if available, fog lights. High beams should be avoided as they reflect off the fog and reduce visibility.
- Low beams aim lights down and forward.
- Fog lights are mounted low and aim light directly in front.
- High beams reflect off fog, causing glare.
- Reduce speed and increase following distance in fog.
Memory trick: When the fog is thick, low beams are the trick!