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From: jis1@mtgzz.UUCP (j.mukerji)
Newsgroups: net.railroad
Subject: Re: Left and right hand running, and speed calculation
Message-ID: <1616@mtgzz.UUCP>
Date: Fri, 31-Jan-86 10:06:57 EST
Article-I.D.: mtgzz.1616
Posted: Fri Jan 31 10:06:57 1986
Date-Received: Sat, 1-Feb-86 06:41:44 EST
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Organization: AT&T Information Systems Labs, Middletown NJ
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> 	Speed in mph = (3600 x (number of miles)) / (time in seconds)
> 
> If timing to the nearest second, try to use 2-mile intervals above about
> 75 mph, otherwise you'll lose accuracy.  For 1-mile intervals we have the
> pairs 60-60, 55.5-65 approx, 48-72, 45-80, 42.5-85 approx, 40-90, 38-95 approx,
> 36-100, 33-109 approx, 30-120, 29-124 approx.  In each case if one number
> is the time in seconds the other is the speed in mph; memorize the pairs.
> If you're going above 125 mph the mileposts are in km anyway.
> 

In Km post territory, the speed in mph is obtained by the following modified
version of the equation posted by Mark:

	Speed in mph = (2250 x (number of Km)) / (time in seconds)

The one that I happen to use more often, since I am more used to Kms than
miles is for calculating the speed in Kmph in milepost territory, and that is

	Speed in Kmph = (5760 x (number of miles)) / (time in seconds)

Jishnu Mukerji