Re: Freight Car Distribution on smaller RRs


--- In STMFC@..., "Mike Brock" <brockm@...> wrote:

Consider: I model only a tiny part of Sherman Hill and only about 3
hrs of
traffic during one op session. 8 frt trains in all. I compress both the
layout and the frt trains...from 75 to 30 cars. About 100 box
cars....or 12
per train if they were applied equally which they were not. Using
the % of
the entire box car fleet, I should have 4 SP box cars. However, in
order to
model the infamous X4005 train with its 36 SP box cars...very close
to 50%
of the known train...I would need 15 SP box cars [ 50% of a 30 car
train ].
To do that and stay within the N-G envelope of 4% of the national
fleet, I
would need 375 box cars. But...I will need more SP box cars to populate
other trains so I'll go with 20 SP box cars. I now need 500 box
cars. The
question then do I apply these 500 box cars to my 8 frt
trains and
their average of 12 per train? In any session the number of box cars
be about 100...leaving 400 in their boxes.

What does this do for the MWR car? Well, nothing. The 1953 ORER
shows 100
MWR box cars. For me to have one MWR box car and match the N-G data
base, I
would need 7400 box cars.

Mike Brock

One way to use the N-G distribution model is to assess "plausibility"
for the presence of foreign road box cars on your layout. Needing one
train with 15 SP box cars doesn't instantly drive you into a huge box
car fleet. But unless the train ran several times a day, it makes a
strong case for letting the X4005 train stay in staging some days, and
perhaps fiddling the other box cars in that train. If you want to
emulate N-G, then I would simply segregate the SP cars dedicated to
this train from the rest of your fleet balance targets. So now you
need 15 SP cars for X4005, and 100 for the rest of your trains to
maintain N-G.

To my thinking, the intent of N-G is make a model railroad visit more
like a stop along the prototype's track. If you randomly stoped along
sherman hill in your era for 3 hours (more if you run a fast clock),
would you expect to see X4005 every visit? IF yes - run it every session.

As for the MWR car, same concept, how may 3 hour visits to sherman
hill before you spot it? One, ten, one hundred? Stats would suggest it
would be pretty infrequent. Same for the Ann Arbor, D&H and other
small roads (although they would appear much more often than the MWR,
but certainly these roads would not be seen every visit).

My lessons learned from this thread are:

1) N-G should apply to mainline trunk routes where the nation's
traffic is traversing a layout.

2) N-G applies to general merchandise deliveries from staging to
almost any industry where captive cars were not used, for most layouts
that received traffic from around the country.

3) It is very doubtful that N-G applies to empties delivered to small
branch lines by a larger road. When/where MTs were in surplus the
large road might send what would take them the longest to get rid of.

4) N-G may apply to MT box cars passing across a layout. It is
doubtful, depending on the era and location, that it would apply to
MTs arriving from staging for use at a specific on-layout yard that
was collecting MT's for distribution.

5) It DOES NOT apply to branch lines, or even medium sized lnes that
were not "trunking" the nation's traffic, in part because some (or
many) cars may be in captive service.

6) Having cars from small roads is perfectly acceptable - but they
should be fiddled in - it could be on a dice roll, or more analytic.
It seems that having an extra 30-60 box cars from smaller lines (and
some of these may be well known lines for a smaller fleet), is all
that is required to provide some sense of "randomness" to trains
entering the layout from staging.

7) It may be worth creating three pools - one of the dominant road's
cars, where nearly all are used all the time (assuming the layout can
handle your collection), one from lines that appear less then every
session, but were numerous. Depending on the extent of your
collection, 20-50% of these cars would be fiddled in each session. The
third pool would be the rarities (e.g. MWR on your UP mainline). If
you had 20 of these cars, you might randomly draw two per op session.

We need to ponder if some of the "attraction" to the rare car is, in
fact, because they were spotted so rarely on the prototype. I would
guess that when 50% of the WWII fleet was owned by 11 roads, spotting
the rare car would be a memorable event. But if you rail-fanned
sherman hill, based on your conductors reports, and saw 8 trains go
by, just how many of the cars would be from fleets smaller than say
the 20th road (C&O)? N-G would suggest that 25% of the cars would be
from these "smaller" lines (SOO, WAB, Erie, N&W, SAL, PM, GTW, RDG,
ACL, SAL, NYNH, DL&W, and over 100 others) Yet the 12 lines listed
have 100 times as many box cars as MWR.

I think the concept has some very positive merit. The good news is
that having 50% of your fleet from the 11 major roads is probably
pretty easy to accomplish, unless your fleet is primarily resin, in
which case I think you can do whatever you want ;-)

And it would not take a large fleet of cars from smaller roads to
create a "prototypical" sense of the occasional rare car passing
through your layout.

The one down side to this is that you need to be able to fiddle your
trains in staging so you can provide a prototypical sense of
"randomness" (I hate to breach the subject of rare car classes and how
often they should appear... Nevermind.)

The interesting finding is that because 50% of the boxcar fleet was in
11 roads, the "fiddle" pools do not need to be huge - 30-60 cars
depending on the size of the layout and the length of the PP's memory
(don't let them collect on-layout wheel reports!) And it is quite
reasonable to run that MWR car once every few sessions. Just don't put
it in a string of D&H, B&M, D&LW, AA, and RDG box cars, or no one may
notice it!

Dave Evans

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