Re: The G-N Distribution Model

Aley, Jeff A



               A couple of points – the G-N model only applies to free-roaming cars (think “plain boxcars”).  Not bottle cars, not hoppers, not reefers.  Not even boxcars in Pool service (auto parts?).  For those, you may develop the “Larrabee Distribution Model”.


               The G-N model only applies to Foreign-Road cars.  The home road is a whole ‘nuther thing.


               What I conclude from the model (given that I model the UP mainline in Kansas), is that I actually do need X29’s and NYC and C&O boxcars, even though Kansas is a long ways from those RR’s territories.  And the proportions of those cars on my model RR should reflect their proportions in the national fleet.  I shouldn’t have 1 X29 with 37 MKT boxcars – the regional bias just ain’t so.  Maybe a particular train would have that variation, but my overall stash of cars should not.









From: STMFC@... [mailto:STMFC@...]
Sent: Monday, September 04, 2017 6:48 PM
To: STMFC@...
Subject: RE: [STMFC] The G-N Distribution Model



Well, thank you Bruce. Yes, you did this in one
sentence. And then instantly provided multiple

And while I think this is a logical extension of
the fact that freight cars are free-rolling, can
be assigned anywhere, look at the trek of the
Monon 1 as an example, on any given day, in any
given train, you can see any given railroad's
freight cars . . . I don't quite believe it.
Sorry. Sorry I asked.

This would suggest that in a train on, for
example, the NP you could, on average, over time,
see the sane, or very nearly the same, consist
makeup as say, on the Southern. Or the UP, Or
the D&H. Or the Rutland, the MEC, the NH, the
M&StL, the CGW, the AA, the NKP, the C&O, the SP .
. .

No wonder Brock obsesses about some damned hopper
going over some hill out west. 8^)

Maybe. But I have a bit of a hard time believing
that the consists of freight trains could be that
homogeneous across the country as that. And that
it would be a good way to establish the mix of
cars you have on your model of the XYZ railroad,
because that's what the G-N Distribution Model

I can easily see how quickly that would get skewed
for any one railroad overall, never mind in
specific areas of a particular road. And I
suppose that's just one of the "excepts."

The ERIE had traffic between steel mills and
rolling mills around Youngstown. So if I were to
be modeling the Youngstown area (it would take a
gymnasium to model that!) I'd need hot metal
bottle cars, as well as more gons than I want to
think about. Plus a lot of hoppers, most likely
from eastern roads. Yeah, well, that's an

The ERIE had a tremendous produce and fruit market
to serve in NYC, so there were reefer blocks,
solid reefer trains, from Chicago to NYC (with a
few diverted to other eastern cities). I'll need
a lot of reefers. Yeah, well, that's a "except."

Maybe other than those "excepts," the composition
of the general freight pool for the rest of the
trains running over the entire line of the ERIE
might conform to the G-N Distribution Model, but I
am not even so sure of that. It seems to me that
there must have been some level of regional

I must say that the responses I've seen from
long-time list members that amount to "weren't you
paying attention?" and offers to send me 1500 of
these emails and also 100 or so from someone else
so I can figure it out for myself certainly don't
reflect the usual level of "here, let me help you
with that" that it typical of this list. I think
the Claus is in much the same boat as I am, which
in effect is "what are you guys talking about?
Please educate me, and put this in an easily
understood form that I can go back to and think
about for my own purposes."

In my first post with this subject line, I asked:
"But is the G-N Model neatly summarized anywhere?"
I'm sorry Bruce, but your one sentence summary
doesn't quite get me there.


From: STMFC@...
Sent: Monday, September 04, 2017 6:50 PM
To: STMFC@...
Subject: Re: [STMFC] The G-N Distribution Model


Yes. Repeatedly. In the archives. But to make it
simple, here it is, again:

Boxcars from any given railroad appear on any
other railroad at the same frequency as they occur
in the national pool.

That's it. Really pretty simple. Note that it does
not govern the frequency of home road cars, or the
frequency of cars in individual trains, but the
overall frequency of foreign road box cars.
Several caveats deal with cars in assigned or pool
service, branch lines in the middle of nowhere,
yada, yada, yada... but the essence is very pure
and simple.



Bruce Smith

Auburn, AL


From: STMFC@...
<STMFC@...> on behalf of 'Schuyler
Larrabee' schuyler.larrabee@... [STMFC]
Sent: Monday, September 4, 2017 5:21 PM
To: STMFC@...
Subject: [STMFC] The G-N Distribution Model


I wasn't very interested in the Gilbert-Nelson
Distribution Model when it was being developed. I
didn't have a layout then (still don't, but maybe
. . .) so I satisfied my Freight Car building
urges by building kits that struck my eyes as
being interesting. Since those times I've settled
(more or less) on modeling the ERIE in the 1950-52
time frame, and thus the G-N Model has become of
more interest to me.

But is the G-N Model neatly summarized anywhere?

And where might I find that?


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