Weather & Seasonal · Driver Training VideoDense Fog

Fog can drop your visibility from a mile down to under a hundred feet in seconds, and it rarely comes with much warning. FMCSA rule 392.14 covers exactly this. In fog, snow, ice, or any condition that affects safety, you are required to reduce your speed.

Here's what that looks like in practice. Slow down before you're in the thick of it, not after you're already blind. Use your low beams.

Open up your following distance

The gap that felt fine in clear weather is not enough here. Your stopping distance hasn't changed, but your warning time has disappeared, so give yourself more space and more time to react to whatever's ahead.

Track the right edge line and any reflective markers to hold your lane position. Don't chase the taillights of the vehicle in front of you — they can vanish the instant fog thickens. And never speed up just because someone behind you is pushing.

If visibility drops too far to drive safely, do not stop in a travel lane. Pull completely off the roadway, as far onto the shoulder as you can get, and turn on your hazard flashers. A stopped truck still sitting in the lane is exactly how fog pile-ups start.

Crack your window

You can often hear another truck or a horn before you can see it. And turn off cruise control — you need to be controlling your speed by hand, not letting the system hold a number that no longer fits the road.

Your company standard: reduce speed before you enter fog, not once you're already inside it. Low beams only, never high beams. Increase your following distance. Never stop in a live lane — get fully off the road and run your hazards until it clears.