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 high beams?
- AWhen the other vehicle is within 500 feet.
- BWhen the other vehicle is within 300 feet.
- CWhen the other vehicle is within 200 feet.
- DWhen the other vehicle is within 100 feet.
Show answer & explanationAnswer & explanation
Correct answer: A. When the other vehicle is within 500 feet.
Federal regulations and most state laws require drivers to dim their high beams when an oncoming vehicle is within 500 feet to prevent blinding the other driver.
Why the other options are wrong
- B. 300 feet is insufficient for preventing glare to oncoming traffic.
- C. 200 feet is still too close for adequate reaction time.
- D. 100 feet is too close; the other driver would be blinded.
Headlight Dimming Distance
The minimum distance at which a driver must dim their high-beam headlights for oncoming vehicles or when following another vehicle.
- For oncoming vehicles: 500 feet.
- When following another vehicle: 200 feet (some states 300 feet).
- Prevents blinding other drivers and improves overall road safety.
Memory trick: 500 feet for oncoming brights, 200 feet for following lights.