Following Distances 

Because many so-called instructors who talked about "the two second rule" truly did not understand what they were talking about, it has wrongly fallen into relative disuse in the USA.

     The important point is that the rule needs to be varied to allow for different road surface conditions.

     Also, even though two seconds is perfectly adequate for a driver who is concentrating properly, many people prefer to extend the times to those shown in parentheses, below.

     Forget useless advice about how many car lengths you should be behind another vehicle at certain speeds; this technique is vague, difficult to judge and therefore often dangerously inaccurate.

     If you feel that you somehow prefer the "car lengths" method, estimate the length of a typical car (stretch limo's do not count!).  What would you say?  Seventeen feet, perhaps?

     At 70mph, a vehicle is covering the ground at 102.6 feet per second so two seconds is, of course, 205 feet. Now compare this with the spurious "seven car lengths" approach!  (7 x 17 = 119 feet and at 102.6fps, this barely allows for "reaction time", let alone any adequate "braking distance".)

     Remember:  "Only a fool breaks the 2-second, 4-second, 10-second rule!"