Frt car populations/frt train consists [ warning...long ]


Tim O'Connor writes:

"Dave Nelson and Tim Gilbert
spent quite a lot of time on BOX CAR distribution research and found that
on almost all class 1 railroads in the STMFC era, the percentages followed
the ORER fleet sizes pretty closely -- excepting home road cars, which are
almost always a higher percentage than their share of the national fleet.
XM box cars in the STMFC era, in other words, were "free roaming" and went
just about anywhere and everywhere."

Not so fast. Tim Gilbert wrote:

"In 1947, the ownership of foreign boxcars aggregated into eight ICC
Geographic Regions correlated pretty well with the percentage those
regions owned of the National Boxcar Fleet. In 1949, that correlation
was blown to hell.

Mike Brock has argued that SP should be given special treatment on
account of it being an interchange partner of the UP. If SP is given
special treatment, then so should be the partners on the East End of the
UP: - the C&NW, MILW and CB&Q. These four roads had 118 of the foreign
boxcars in 1947 (vs. the equivalent of 105 which their percentages of
the national fleet warranted), and 340 of the foreign boxcars (vs. 212
of the percentages)" [ in 1949 ].

The issue, obviously, is can the data from a thirty fourth of the trains
traversing between Laramie and Rawlins on the UP mainline predict the
consist of box cars regarding railroad ownership during the period of
examination? The consist in question would be from a "fleet" perspective.
IOW, the data might predict 34 Mopac box cars during the month and a half of
examination. OK, what about a train? Would the 34 Mopac box cars be
expected to spread themselves so that one would appear in each of the 34
trains. I quick perusal of SP box cars in the 34 trains shows definitely no.

The presence of frt cars in trains moving across Wyoming [ a trunk line ] seems from the available data to be to a great extent driven by the type of cargo being carried and by the tendency to group by such cargo. This grouping seems to generate trains of frt cars, at times, with a common cargo and common car type and even railroad type...hence: lumber, oil, stock, coal, ore etc. In order to model these types of trains, with the necessary compression due to layout size, which necessarily contain more cars of a specific railroad [ for example, SP in the UP Wyoming case ] than the national per cent might call for appears to require the modeler to maintain significantly larger populations of such frt cars than the national per cent. OTOH, the modeler would need to develop some technique to guard against spreading cars from the larger population evenly throughout the modeled frt trains.

To add to these points, I will resend a message I sent to the
group a yr or so ago:

Both Tim Gilbert and Dave Nelson have contributed mightily in providing
needed enlightenment regarding freight car populations...particularly
with respect to much traveled box cars. What follows is in no way meant to
subtract from their very useful efforts. Rather, it is an attempt to
present information that seems to demonstrate that the modeler wishing to
simulate the traffic population of box cars in trains using a relatively much
smaller fleet of cars than that producing the overall population may need to
accumulate box cars disproportionate to the number expected in
population analysis. We all know, that due to various reasons,
individual frt train content varied from train to train. The trouble is,
the variance, in some cases, was least on the UP in central

Here is an analysis from my Fraley Conductor's Book showing how SP box
car populations varied over 34 trains. Oddly, the results match what is seen
on the Pentrex video tape...The Big Boy Collection....although that is no
doubt mere luck.

1. 34 frt trains were composed of 2787 cars of all types and all RRs.
2. The average train length was 81.97 cars.
3. There were 136 SP box cars in the trains which is 4.9% of the total
4. There is an average of 4 SP box cars per train.

OK...that was easy enough. Uh oh....

5. There were 15 trains with one or less SP box cars. In fact, 9 had
none at all.

6. Two trains had a total of 42.3% of the SP box cars...27 + 31 cars. Two
others had 9 each. Thus 4 trains had 76 cars or 55.8%. 29 trains had 5
or less SP box cars.

The reasons for the deviation from the common 5 or less cars is possibly
driven by source, destination and commodity.
Each of the trains with the high number of SP box cars
were east bounds with primarily lumber loads. Train #6 had 22 loads of
lumber of the 27 SP box cars. Train #28 had 26 loads of lumber in its 31
cars. Destination is also interesting. Of the lumber loads in train #6,
all went to O [ or o ] or KC. Of the lumber loads in train #28, all but 3 of
the 27 went to O [ or o] or KC. All 9 of the SP box cars in train #23 were
MT.I expected to see a larger number of MT SP box cars in a I believe is seen on the Big Boy tape. Three trains having a combined total of one SP box car appears to
have originated in the northwest, they having a large number of apples and
spuds in the consist.

Of course the Fraley book contains a realtively small sample of data.
During the fall of 1948...6 months prior to the Fraley data...UP averaged about
26 frt trains per day through the Altamont Tunnel between Green River and
Evanston. This does not include the Granger cutoff traffic through
Montpelier which in 1956 averaged about 12 trains per day. One can
probably be fairly safe in assuming about 35 frt trains per day through the Green
River-Laramie area. Thus, our sample is 1/35th of the approximate number
of trains IF Fraley worked every day...which he did not. He actually worked
only 72% of the days. In all, using the average number of cars for the
trains he did work, about 134,890 cars went through Laramie during the
time in question. We have the data for 2787.

So, are the high number of SP box cars in trains #6 and #28 an

Since the Big Boy tape shows a similar train, I think not. So, does the
modeler use the Fraley data and wait until 17 frt trains operate and
throw one in with say, 45% of the train being SP box cars? Perhaps other
Fraley books will reveal other trains with high SP box car numbers.
Incidentally, I saw no other road so well represented except, of course, UP. I'll, take
a look at NYC, Pennsy, C&NW and Q later. It is interesting to see a block
of 9 MT cars with the name "RD" headed west. My guess is Santa Fe reefers.
Other SP cars of note in the Fraley book: 9 flat cars with loads of
rail, vehicles [ eastbound? ], tractors, trucks [ eastbound? ], and board. 5
gondolas with rail [ westbound ], and tank car 58403 with some kind of
oil. One curiosity is SP box car 33764 with a load of meat bound for KC.

Finally, the UP Perishable and Manifest schedule contains a list of
destination codes. Fraley seems to have added his own...possibly those
informally in use at the time. Hence, he opts to use the mile marker for
a city one time [ 510 for Cheyenne ], the actual name another. A frequent
destination is O or o. This could be for Omaha but, given the large
number of entries, I opt for mile marker 0.0...Council being the
end of UP tracks eastbound.

To summarize, UP frt train consists in Wyoming appear to have varied
quite a bit with respect to SP box the extreme compared to their usual
populations. This is possibly due to the rather unique relation with SP,
it being UP's major connection to central Cal. We know that SP generated
Overland Route trains tended to stay intact since their car's destinations were either large
metroploitan areas [ KC ] on the UP or they were headed east of UP
tracks. How this is similar to other RRs is dependent on many other factors. My
unknowing guess is that UP was rather unique in it being a trunk line
with adjoining SP and C&NW. IOW, Santa Fe, also with a trunk line, doesn't
seem to have a partner like SP. SP, itself, may have had a smaller
relationship with SSW.

Mike Brock

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