What is the purpose of the "three-second rule"?

The "three-second rule" is a guideline used to help drivers maintain a safe following distance behind the vehicle in front of them. By ensuring that a driver stays at least three seconds behind the vehicle they are following, it allows for adequate reaction time should the leading vehicle suddenly stop or slow down. This measure is especially important in preventing rear-end collisions, as it provides a buffer that accounts for the speed of both vehicles, road conditions, and the driver’s ability to react quickly in unexpected situations.

To apply the rule, drivers can select a fixed point on the road as a reference—such as a sign or a tree—and count the seconds it takes for their own vehicle to reach that point after the vehicle in front has passed it. If they reach that point in less than three seconds, it indicates they are following too closely and should increase their distance.

Maintaining a safe following distance not only enhances safety but also promotes smoother traffic flow, as it reduces the likelihood of sudden stops and startle reactions among drivers.