Re: Perishable traffic


al_brown03
 

Herein lies the fascination. The underlying question is "how random
was freight-car movement?" The closest we are to an answer
is "somewhat but not totally, and it depends". Some equipment moved
highly predictably, e.g. Dow Chemical bromine cars in dedicated
service. Other cars appear in places that just seem bizarre, e.g. a
Clinchfield stock car in Alamosa, Colorado. It's clear that freight-
car distribution on a particular line depends heavily on the function
of that line, not just of the railroad. Say you model "SAL in
Florida": do you model the Orlando Sub or the Bone Valley? For the
Bone Valley, you need lots of phosphate hoppers, few reefers; for the
Orlando Sub, the other way around (and maybe some tanks of avgas for
Orlando AFB). The Chubb formula was state-of-the-art 30 years back;
we're far past that now, but we've still just scratched the surface.
There's lots to learn.

Of course, any realistic car-movement scheme must reproduce the well-
known fact that coelacanth oil was shipped over Sherman Hill in U.S.
Coast Guard tank cars, the prototypes of the Tichy model. :-)

Al Brown, Melbourne, Fla.



--- In STMFC@yahoogroups.com, "David Smith" <dsmith@...> wrote:

And here we have the modelers' version of the Heisenberg Uncertainty
Principle... You can model a given day with high precision and you
sacrifice precision in the overall fleet or you can model the
overall
fleet with high precision and you sacrifice precision on the actual
consists of any given day. Neither one is inherently more precise
than
the other, just different. And what we will never have, but would
be
fascinating, are the logs of individual cars over their lifetimes.

Dave Smith

David L. Smith, Ph.D.
Director of Professional Development
Da Vinci Discovery Center, Allentown, PA
http://www.davinci-center.org
"Who will pick up where Leonardo left off?"



-----Original Message-----
From: STMFC@yahoogroups.com [mailto:STMFC@yahoogroups.com] On
Behalf Of Mike Brock
Sent: Friday, March 03, 2006 12:13 AM
To: STMFC@yahoogroups.com
Subject: Re: [STMFC] Perishable traffic


Tim Gilbert writes:

Mike Brock wants to know how
many of these mostly SFRD reefers went through Valhalla
(a.k.a.
Sherman Hill).
After reading through all the messages on perishable traffic
I'm not certain
what I want...except perhaps a new thread. Curiosity is, of
course, a
significant motivator so I suppose one might be drawn to
wanting to know
which RR in the east carried the most perishables the
greatest distance but
I doubt we'll ever know and, if we do find out, nothing much
will change as
far as modeling and/or simulating the actual traffic pattern
is concerned.
IOW, if, instead of modeling Valhalla, I modeled a much less
significant
area...like...well...say Altoona and Horseshoe Curve <G>, and
I did it in a
similar way to what I did with Valhalla, I can't really see
what any of this
would have to do with my efforts. I would, of course, do
scenery. That would
dictate within a range of perhaps 4 months when the model
portays the area.
Hence, what happened over a yr wouldn't really matter. What
happened during
4 months would but I'd only be modeling about 3 hours of a
given day. Thus,
I'd only be sampling 1/8th of the possible traffic. The
key...IMO...to
modeling with some accuracy this little known area would be
to have frt
train consists...frt conductor books...available. Just
knowing the totals
for a full yr...while interesting...still fails to deliver
accurate
information regarding a frt train that one might choose to
model. Returning
to Valhalla again, I seriously doubt that yearly totals would
predict that
on May 14, 1956, a UP frt train would travel from Cheyenne to
Laramie with
fully 95 SFRD reefers in tow. Fortunately, since the train
DID exist, it was
traveling west...and, therefore did not break Brock's Fourth
Rule of Frt
Trains...SFRD cars shall travel only westward on UP
tracks...MT no doubt.
So...what should one do if they WERE modeling the Altoona area?
Well...that's a good question...far beyond my knowledge base
but one thing's
for sure. They could have just about any frt car model
made...just like
those modeling Valhalla. The numbers of each on a given day
would depend on
daily wheel reports, not on yearly totals...IMO. I realize,
of course, that
such might not be available and, hence, we might find yearly
totals the only
game in town. In that case, yearly totals would have to used to
predict...but we should be aware of their inherent inaccuracies.

Mike Brock




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