Mike Brock <brockm@...>
Given the recent messages associated with frt car populations and their use in predicting frt train consists, 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
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
information that seems to demonstrate that the modeler wishing to
the traffic population of box cars in TRAINS using a relatively much
fleet of cars than that producing the overall population may need to
accumulate box cars disproportionate to the number expected in
analysis. We all know, that due to various reasons,
individual frt train content varied from train to train. The trouble is,
variance, in some cases, was extreme...at least on the UP in central
Here is an analysis from my Fraley Conductor's Book showing how SP box
populations varied over 34 trains. Oddly, the results match what is seen
the Pentrex video tape...The Big Boy Collection....although that is no
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
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
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,
went to O [ or o ] or KC. Of the lumber loads in train #28, all but 3 of
27 went to O [ or o] or KC. All 9 of the SP box cars in train #23 were
I expected to see a larger
number of MT SP box cars in a train...as I believe is seen on the Big
tape. Three trains having a combined total of one SP box car appears to
originated in the northwest, they having a large number of apples and
in the consist.
Of course the Fraley book contains a realtively small sample of data.
the fall of 1948...6 months prior to the Fraley data...UP averaged about
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
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
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 134,840 cars went through Laramie during the
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
one in with say, 45% of the train being SP box cars? Perhaps other
books will reveal other trains with high SP box car numbers.
saw no other road so well represented except, of course, UP. I'll, take
look at NYC, Pennsy, C&NW and Q later. It is interesting to see a block
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
vehicles [ eastbound? ], tractors, trucks [ eastbound? ], and board. 5
gondolas with rail [ westbound ], and tank car 58403 with some kind of
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
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
of entries, I opt for mile marker 0.0...Council Bluffs...it being the
UP tracks eastbound.
To summarize, UP frt train consists in Wyoming appear to have varied
bit with respect to SP box cars...to the extreme compared to their usual
populations. This is possibly due to the rather unique relation with SP,
being UP's major connection to central Cal. We know that SP generated
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
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
adjoining SP and C&NW. IOW, Santa Fe, also with a trunk line, doesn't
to have a partner like SP. SP, itself, may have had a smaller