5 ms·

This is taught around day one of the mandatory theory course kids take before being allowed to even try for their licenses here. And it's on the theory tests th

• D9u 13y ago
  I seem to remember that a minimum interval of two seconds was the rule for following another vehicle, but the whole car lengths thing always threw me... Are we talking Lincoln Continentals, or Volkswagon Beetles?
  • lutusp 13y ago
    > I seem to remember that a minimum interval of two seconds was the rule for following another vehicle ... That's a reasonable rule of thumb, but it doesn't work in all cases -- it makes too many assumptions. It only takes driver reaction time into account, and it serves to partly explain why accidents in fog tend to involve many cars and high levels of injury and destruction. The reason? The two second rule assumes the car in front of you has the same stopping distance characteristics as your car, once the brakes are applied. But if the car in front of yours abruptly stops by hitting an immovable object (instead of skidding to a stop) and you are two seconds behind him, you will surely collide with him also, and the car behind you will collide with you, ad infinitum. People who drive at normal speeds in fog apparently don't realize this. So a new proposed rule -- if you can't see the car in front of the car in front of you, pull over and catch up on your reading. I doubt this rule will take hold.