What do you follow – the second rule?
One of the very first defensive driving program was the Smith System of Defensive Driving, which was devised in the 1950s by three researchers, Harold A. Smith, John J. Cummings and Reuel A. Sherman. Smith was a professional driving instructor who worked for the Ford Motor Company in its fleet driving division, Cummings was an accident investigator and Sherman was a recognized authority on occupational vision.
This system is also called “Space Cushion Driving”. The belief was that if you have more space around your car, you would have more room to maneuver, less surprises and that would lead to fewer collisions. And you know what? He was right! He was one of the first advocates of a following distance rule. You might remember the 1 car length for every 10 miles per hour. This then in later year evolved to the Time Interval Formula or as we call it the 2 second rule. For professional drivers it is actually 1 second for every 3 meters of length of your truck.
However we are recommending adding 2 seconds to this formula, so it would be 1 second for every 3 meters of length + 2 seconds.
The original formula was based on Space and Driving
Reaction Distance + Braking Distance = Stopping Distance
I think that something is missing
? + ? + Reaction Distance + Braking Distance = Stopping Distance
The extra seconds are for Perception Time and Decision Time. Reaction time is about 3/4 of a second so by allowing an extra couple of seconds we provide that extra margin of safety.
The original formula was based on the assumption that everyone is in an active/proactive mode 100% of the time. Remember our core philosophy?
Regardless of anyone’s knowledge, skill, experience or training, there are some days that we are better than other days By habitually add an extra couple of seconds to our following distance we give a space cushion even when we are not quite in an active/proactive state.
Driving with the Intention of Space
The key to good space cushion driving is driving with the “Intention” of space. While you do not control what other people do, you control what you do and you have the ability to manipulate the space around your vehicle. If you can make space an intention and a priority while you drive, you are more active in your driving and change your driving for the better on a day to day basis. Some Space driving hints are:
- Look and drive to the open space
- Stay out of hit zones
- Keep clear of blind zone areas
- Build space as you approach intersections
- Control your space