CDL General Knowledge TestDriving SafelyMedium
You are driving a commercial vehicle at night and another vehicle is approaching from the opposite direction. When should you dim your headlights from high beams to low beams?
- AWhen the other vehicle is 500 feet away.
- BWhen the other vehicle is 200 feet away.
- CWhen the other vehicle is 1,000 feet away.
- DOnly when the other driver flashes their high beams at you.
Show answer & explanationAnswer & explanation
Correct answer: A. When the other vehicle is 500 feet away.
Federal regulations and most state laws require commercial drivers to dim their headlights when an oncoming vehicle is within 500 feet to prevent blinding the other driver. Waiting until 1000 feet (A) is too early, and 200 feet (C) is too late to prevent glare. Waiting for the other driver to flash (D) is reactive and unsafe.
Why the other options are wrong
- B. Dimming at 200 feet is too late and can still cause temporary blindness for the oncoming driver.
- C. Dimming at 1,000 feet is generally earlier than legally required and might reduce your visibility unnecessarily.
- D. Waiting for the other driver to flash their high beams is reactive and does not ensure safe driving conditions for others.
Headlight Dimming Distance (Oncoming)
The required distance at which a commercial driver must dim their high-beam headlights when an oncoming vehicle is approaching.
- Mandated by law for safety.
- Prevents temporary blindness (glare) for other drivers.
- Standard distance is 500 feet.
Memory trick: Five hundred feet, eyes meet, dim your brights, make it right.