No, the 2 second gap is based on the fact that a modern car can decelerate, under maximum braking, at about 20mph per second. So a 2 second gap at 60mph means that the driver has 4 seconds to stop (since his average speed over that time will be half his starting speed). That gives 3 seconds to get rid of 20mph per second, plus 1 second for the driver to react.
Personally I prefer a bigger gap than that. I try not to ever plan to use maximum braking, it is too close for comfort. A five second gap at 60mph goves the driver time to look in his mirrors, search for spped cameras, check his speedometer and do all the other unnecessary things he is called upon to do these days.
Even better is my preferred distance of 1 sec per 10 MPH. This gives the driver time to look several vehicles ahead, and in such situations I don't need to hit the brakes as soom as I see brake lights ahead. I can take the time to decide whether braking is actually necessary, and perhaps save fuel and wear and tear on the car. It''s surprising how often just lifting off is enough.
Martin
-- Created on the Iyonix PC - the world's fastest RISC OS computer.
