Driving in Fog
What the exam tests
Visibility-limited driving, light use, and safe stopping in fog.
Core rules
- Use low beams, not high beams. High beams reflect off fog and reduce visibility.
- Use fog lights if the bus has them.
- Slow down and increase following distance.
- Use wipers and defroster to keep the windshield clear.
- If visibility is too low, pull completely off the road, stop, and turn on four-way flashers. Do not stop in a travel lane.
- Do not use cruise control.
- Listen for traffic and roll down the window at intersections if needed.
- Fog often comes in patches; visibility can drop suddenly.
Worked example
Fog cuts visibility to about a quarter mile. You reduce speed, switch to low beams, and double your following distance. When fog thickens, you pull into a parking lot rather than stopping on the shoulder. Reasoning: a vehicle on the shoulder can be struck; a parking lot is safer.
Traps that cost marks
Using high beams; stopping in the lane; tailgating to follow taillights; driving at the posted limit regardless of visibility.