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 our roads. Each...
How do you work that out? A 3 second gap is a 3 second gap, not a five second gap. How much time you actually have depends on how long the vehicle you are following takes to stop.
In emeorgency braking you will need a second for thinking time plus another second for each 20mph (in good conditions). If that space isn't availale you will collide. Say 5 seconds at 70mph. Of course if the conditions aren't good, or you prefer to have a safety margin you need more.
True, but you need some safety margin to cover things like momentary inattention whilst you look in your mirrors, at you speedo etc.
And it relies on the buttumption that the vehicle you are following won't stop dead. This is a false buttumption as I found out yesterday.
I wonder hw many of the 20 or 30 vehicles that were involved yesterday were driving to a 2 second gap!
You actually gain nothing by following too closely. So why not leave plenty of space, you will get there just as quickly. You can maintain the same speed following 5 seconds behind as you can half a second behind. But with a 5 second gap, you will have time to look well ahead and use your mirrors, rather than hjaving to concentrate on the back of the car in front in case he brakes. All of these things inprove your safety.
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