What is the three second rule used for?

The three-second rule is primarily used to ensure proper following distance between your vehicle and the vehicle in front of you. This rule helps drivers maintain a safe spacing that allows adequate time to react to sudden stops or emergencies that may occur.

To apply the three-second rule, you select a fixed point on the road—like a sign or a tree—and when the vehicle ahead of you passes that point, you start counting seconds. If you reach the same fixed point before you finish counting to three, you are following too closely, and you should increase your distance. This practice helps prevent rear-end collisions and gives drivers a buffer to assess and respond to changes in traffic conditions.

While determining safe driving speed, calculating stopping distance, and gauging reaction time are all important aspects of driving, they do not specifically relate to the purpose of the three-second rule in promoting safe following distances.