When driving at night, how fast should you drive?

• A. At the posted speed limit
• B. As fast as road allows
• C. Ten miles per hour
• D. Slow enough to stop within headlight range

Answer: (D)

When you drive at night, you need a speed that matches the limited visibility. Your headlights only reveal a certain distance ahead, and glare or slick pavement can reduce that range. Because your stopping distance increases with speed, you must drive slow enough to be able to stop within the distance you can see with your lights. This helps you react to hazards you glimpse and brake in time. So you should drive slow enough to stop within headlight range, adjusting for weather, road conditions, and traffic. Driving at the posted limit or as fast as the road allows ignores night-time visibility, and an arbitrary fixed speed isn’t safe.