California Car / Permit practice question · Safe Driving Practices

The "three-second rule" is used to help you:

Answer choices

• Time how long a yellow light will last
• Keep a safe following distance behind the vehicle ahead— Correct answer
• Decide when it is legal to change lanes
• Estimate your total stopping distance in fog

Why this is the answer

The three-second rule gives you a safe following distance, so you have time to react if the driver ahead brakes suddenly. Tailgating blocks your view and leaves you too little time to stop. It does not time yellow lights or decide when to change lanes. Create even more space when someone is tailgating you or conditions are poor.

Source: California Driver Handbook — Following Distance

Content reviewed against official driver handbooks · August 12, 2026