Well, I doubt that any vehicle you driver can stop from 70mph in 3 seconds. The first rule of driving is always make sure that you can stop in the distance that you know to be clear. In this case you clearly can't.
BBC Radio 4 RoutemastersRadio 4 is currently repeating a short series of 5 programmes about the history behind various aspects of the traffic control devices we usually take for granted on...
So, when maintaning a 2 to 3 second gap you are relying on the vehicle you are following taking as much space to stop as you will under emergency braking. On a dry road and in most situations where you can see a long way ahead you can probably anticipate in time if the car ahead of you is going to hit something solid. Even so, I like to maintain a good gap if i can, and it annoys me that sometimes other drivers fail to appreaciate this and tailgate me, even though i am travelling at the same speed as the vehicle i am following. This was the case with the car transporter I mentioned who tailgated me on the M25. If I had responded by closing up on the car i was following, it would actually have increased the danger of his own situation.
Emergency braking in dry conditions will shed about 20mph per second. If you prefer less frezied braking it is a good idea to allow twice that, which is what I try to do (it isn't always possible, since people will keep cutting into your baking space. Such is our culture where drivers are not educated to understand the real physics of their situation.
But when you can't see that far ahead, as today, you just don't know what is going to happen. It scares me to rest that the vast majority of motorway drivers don't seem to know this. God help me if i ever have to stop in fog on a motorway.
-- Created on the Iyonix PC - the world's fastest RISC OS computer.
