Tony Bryer wrote:
On Wed, 9 May 2007 19:13:49 +0100 Roger wrote :
I can't find a single copy of The Highway Code atm (I have 3 stretching
back over the later half of my driving experience) but ISTR that the
formula is 0.5 seconds thinking distance plus retardation at two thirds
g. I wouldn't doubt halving the thinking distance but retardation well
in excess of g from an ordinary road car seems a little suspect to me.
IIRC brake efficiency for cars only needs to be 50% so was it that that

http://www.highwaycode.gov.uk/09.htm

In the units in which I learned to drive,

stopping distance (ft) = v(1+v/20) where v is the speed in mph

or v + v^2/20 thinking time approx 2/3 second and 0.6G ?

IF you are a habitual fast driver thinking distance is about 0.2 seconds
or less.

However 0.6g is pretty fair..many trucks and vans won't do that..many
sports cars will do .8-1g or so..but few more than that.