California DMV Permit Test (Class C)Rules of the Road and Right-of-WayMedium
You are driving on a freeway and notice a car several car lengths ahead of you in your lane. To maintain a safe following distance, you should use the 'three-second rule.' How is this rule applied?
- AWhen the car ahead passes a fixed point, you should count 'one-thousand-one, one-thousand-two, one-thousand-three' and only reach that same point after the count is finished.
- BYou should maintain a distance of exactly three car lengths behind the vehicle ahead at all times.
- CWhen the car ahead passes a fixed point, you should count 'one-thousand-one, one-thousand-two, one-thousand-three' and reach that same point before the count is finished.
- DYou should be able to stop your vehicle completely within three seconds if the car ahead stops suddenly.
Show answer & explanationAnswer & explanation
Correct answer: A. When the car ahead passes a fixed point, you should count 'one-thousand-one, one-thousand-two, one-thousand-three' and only reach that same point after the count is finished.
The 'three-second rule' is a method to estimate a safe following distance. When the vehicle in front passes a fixed point, you should not reach that same point until at least three seconds have passed, providing adequate stopping time.
Why the other options are wrong
- B. Three car lengths is a poor estimation and doesn't account for varying speeds or road conditions; the time-based rule is more accurate.
- C. This is incorrect; reaching the point before the count is finished indicates you are following too closely.
- D. While the rule is related to stopping distance, it's a measure of time, not a direct measure of stopping capability within a fixed time.
Three-Second Rule
A method to ensure a safe following distance by counting three seconds after the vehicle ahead passes a fixed point before your vehicle reaches that same point.
- Time-based distance
- Increases with speed/conditions
- Provides stopping time
Memory trick: Three seconds to safety!