[SystemSafety] Small but useful Detail on Road Stopping Distances

[Mike Ellims]

I find it simplest to note when the car in front passes a fixed object and
count one elephant, two elephant, three elephant.

-----Original Message-----
From: systemsafety-bounces at lists.techfak.uni-bielefeld.de
[mailto:systemsafety-bounces at lists.techfak.uni-bielefeld.de] On Behalf Of
Steve Tockey
Sent: 30 July 2015 15:38
To: David Haworth; Peter Bernard Ladkin
Cc: 'The System Safety List'
Subject: Re: [SystemSafety] Small but useful Detail on Road Stopping
Distances


We were taught (in the US), "One car-length per 10 MPH" as in if you're
going 50 MPH then leave 5 car lengths distance between your car and the one
in front.


Cheers,

-- steve



-----Original Message-----
From: <systemsafety-bounces at lists.techfak.uni-bielefeld.de> on behalf of
David Haworth <david.haworth at elektrobit.com>
Organization: Elektrobit Automotive GmbH
Date: Wednesday, July 29, 2015 11:18 PM
To: Peter Bernard Ladkin <ladkin at rvs.uni-bielefeld.de>
Cc: 'The System Safety List' <systemsafety at techfak.uni-bielefeld.de>
Subject: Re: [SystemSafety] Small but useful Detail on Road
Stopping	Distances

Peter,

On 2015-07-29 15:58:35 +0200, Peter Bernard Ladkin wrote:
> The traffic law in Germany stipulates a reaction time of 1 second.

The "halber Tacho"* rule for driving on the Autobahn approximates to a 2
second reaction time (since your safe distance behind another car doing the
same speed is just your reaction time, all other things being equal). Or one
second plus "engineering tolerance" ;-)

* For people not familiar with the German guidelines, you take your speed in
km/h, divide by two, and that gives you your "safe" distance in metres.

Incidentally, the UK has a 2 second guideline for the same purpose. And they
used to have a snappy slogan: "Only a fool breaks the 2-second rule". One
advantage of this over the "halber Tacho" rule is that it is easier to apply
in practice.

Cheers,
Dave


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