pierson@kirk.DEC (02/24/86)
"She sure is coming, wasn't she"...
Comment attributed to a mid thirties train watcher who had just seen
the CB&Q Zephyr come through.
Two more methods of clocking trains. Some analog watches have a
calibrated ring around the outside, called a tachymeter. Used from one milepost
to the next this gives the speed directly. Mine has a scale that runs from
60-400mph, but some are numbered for slower speeds. I believe similar functions
are starting to show up on digital watches.
Another approach, more appropriate to watching than riding, involves
using the lengths of the cars. The simplest are TOFC cars (pigs) as they are
right around a hundred feet long. Lengths for other cars are stenciled on the
cars, if you can read that fast..., 60 or 70 feet is probably a fair average.
First, time a string of, say, ten cars. The longer string the better as
observer errors go down.
Multiply out to get feet per second.
Convert f/s to mph by multiplying by .68 (.7 is close enough for most
people).
Ferinstance: I watched a freight climb into Hoosac Tunnel this weekend.
Ten pigs took 20 seconds, which gives 50 f/s. or 34 mph.
Is it fair to assume that people on a computer net can do the math??
Alternately, a calculator wristwatch (pen, tieclip, beltbuckle, whatever) can be
used. Clearly the accuracy is limited by the assumptions around length of car,
but the results should be closer than guesses.
(DEC E-NET) Kirk::pierson
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