Many years ago, I was outside a courtroom waiting with our expert witness about to testify. As we talked, this expert, an accident reconstructionist who had studied and analyzed thousands of traffic crashes, shared his favorite tip to increase driving safety: don’t tailgate.
The expert suggested that drivers should pretend their cars are equipped with long spears. (No, not as a weapon for imaginary battles on the highway, but as a way to visualize the safe distance between vehicles.) The faster a car is traveling, the longer the car’s spear should be. This expert recommended that a driver leave at least one car-length between his vehicle and the vehicle ahead for each 10 miles per hour of travel speed.
The 3-Second Rule
That conversation took place a long time ago. Although the advice to leave safe following distance is unchanged, a more modern way to gauge that distance is by using the 3-second rule recommended by the National Safety Counsel. Using this method, you choose a stationary object on the side of the road (a telephone pole, for example) and when the vehicle immediately in front of yours passes that object, you count how many seconds until your own vehicle reaches the object. At least three or more seconds should pass before your vehicle reaches the object.
The 3-second rule is a MINIMUM safety rule for use under normal driving conditions, and many say that the MINIMUM actually is a 4-second rule. Experts also advise that one additional second of time should be added for each factor that might affect how quickly you can stop your vehicle. Faster speed, a heavier vehicle, darkness, and wet or icy road conditions are all factors that might require you to use a 5-second rule, an 8-second rule, or even a longer time to allow a sufficient margin for safety.
Tailgaiting is a frequent cause of collisions and injuries that can easily be avoided by following simple safety rules. You can learn more about safe following distances at these websites: