Friday, March 11, 2011

Modeling freight traffic: Coast Line, 1953-Part 7

I have analyzed the box car data in the 1948–1952 conductor’s book I mentioned in my previous post on this topic (analyzing refrigerator cars, at The box car data only extend to April of 1951 and are a mix of loads and empties.
     The sample contains 139 cars. Of these, 40 are SP cars (and 10 are T&NO cars), making the home road (SP) 29 percent of the total. If the T&NO cars are combined (and certainly SP and T&NO freely shared box cars), the SP system total of 50 cars amounts to 36 percent.
     This provides one answer to a persistent question modelers ask: what proportion of home road cars should I model? I noted in an earlier post touching on this topic (available at that I expected, on the basis of photographic evidence, to have about a third of my cars should be home road cars. That is in fact quite close to the 36 percent just stated, but only with the inclusion of T&NO cars. For SP cars alone, it is below 30 percent.
     The remainder of the box cars in this sample are dominated by a few roads. These include PRR (11 cars), GN (8 cars), Southern (7 cars), and NP (6 cars). Following those four railroads are IC and NYC (5 cars each), and SLSF (4 cars). A surprising note is struck by CP with 3 cars and CN with one, more than might have been expected; and at least two of the CP cars were being loaded at Salinas for delivery elsewhere in the U.S.
     Minor parts of this sample were ATSF, B&O, CB&Q, MP, and Wabash, with 3 cars each; and C&NW, MILW, SAL, and UP, with 2 cars each. Finally, single cars were listed for C&EI, D&RGW, EJ&E, Erie, GM&O, GTW, MKT, NC&StL, L&N, P&LE, RI, SP&S, SSW, T&P, WM, and WP.
     Are there surprises here? A few. Two roads with substantial box car fleets, ACL and C&O, do not appear. It is a little surprising that NYC cars are less than half of the PRR total, though the two roads had similar-size fleets of box cars, and roads with large box car fleets, such as B&O and Milwaukee, are lightly represented.
     What about the well-known Gilbert-Nelson hypothesis? I would hesitate to draw much of a conclusion on the basis of only 139 cars, but certainly the biggest box car fleets all show up with significant contributions, even if not necessarily in rank order with fleet size. As just mentioned, there are some surprises. In percentage terms, PRR and NYC each owned about 9 percent of the national box cars in 1953, and indeed PRR cars are 8 percent of this Coast Line sample; but NYC cars are less than 4 percent. The B&O fleet was about 4 percent of the national total in 1953, and here we observe about 2 percent B&O cars. Those same relative values, 4 vs. 2 percent, apply also to Milwaukee Road.
     There are also some roads which are, in Gilbert-Nelson terms, over-represented. These include GN, about 3 percent of the national fleet but nearly 6 percent of this sample; and SLSF, with 1.8 percent of the national box cars but almost 3 percent of this sample. But again, with a small sample, distortions are inevitable. One car more or less from some of these roads would greatly alter their standing.
     Modeling lessons here, as with many things, are in the eye of the beholder. For me, the main observation from this sample is the proportion of home-road box cars, around a third. That’s something I can and will use in my fleet planning and operation.
Tony Thompson


  1. Car Fleet Mix by Road by Era
    The mix of road names expected to be seen on your modeled layout is truly based on the available data. In your 1953 era the known information provides you with a 29% to 36% ratio of “home road” cars. I was surprised that your direct interchange roads didn’t have a much greater presence, which may be particularly explained by the location of you branch. The SP interchanges with GN and SP&S (NP) to the north and northeast. The UP and D&RGW to the east at Ogden, the ATSF from San Francisco to Houston, The WP in San Francisco/Oakland and the Rock Island and Texas & Pacific in El Paso (southeast) with the Southern, Illinois Central and I suspect a couple of others in the southeast at New Orleans and the SSW (Cotton Belt), SLSF and Missouri Pacific throughout Texas. The fact that you see a lot of PRR, B&O, EJ&E, SAL, WM, Erie and other eastern lines reminds us that the majority of the production capability during the early 50’s was on the east coast.
    Since there are not competing railroads in your part of the modeled “world,” provides the rationale for very few cars from the competing and overlaid for most of the Espee’s route from the AT&SF. The existing Traffic Agreements of the era, I suspect as you have mentioned in your discussions of the car types expected to be seen on the central districts of the Coast Division explain a lot of why a lot of cars weren’t seen in SLO.
    In my own case, when I was able to locate some specific data for the 1891-3, 1908 and 1917 era in Central Colorado, I found that each of those three time periods had different mixes of roads showing up. In the 1891-3 period, the direct interchange (AT&SF, Rock Island, Missouri Pacific, D&RG, the Rio Grande Western and Union Pacific, Denver & Gulf) predominated the fleet seen and the secondary interchange lines (SP/CP, CB&Q, B&MR, SP Atlantic Lines) were represented at a level of about half the number of the direct interchange lines. In this era the private car lines put about 20% of the cars seen on to the line (primarily reefers and stock cars due to the expense of these kinds of cars.) In the 1908 era we see a greater diversity of the roads on the line reflecting the nature of rail traffic at that point of history, where if you wanted something shipped it went by rail. The greatest increase on the Midland was the amount of UP owned cars seen in Central Colorado as the traffic from both the San Pedro, Los Angeles & Salt Lake and the Oregon Short Line got routed through Central Colorado to eastern customers and Gulf ports. During the 1908 period more that 50% of the traffic was in foreign cars. By 1917, most of the traffic was local and very few foreign cars are seen (15%). Several cars appear to have been “captured” by the CM and used in local traffic, probably because they were better than the 30 year old, 34’ cars available in the Midland car fleet.
    I suspect you would have different but similar findings if you were to attempt to determine the composition of the car fleet on your “branch” if you changed your era. I had failed in my own studies of the history of the prototype line to realize the changing composition of the car fleet until I found the data and started the analysis. So hopefully anyone who might want to model the Espee in the SLO area in the ‘Pre-Take Over Days” of the late 80s or early 90’s would find a very different composition to their fleet.

    Thanks for listening


  2. Good comment, Tom, and in some ways very relevant, in other ways not very relevant. Before about 1910, the various Car Service Rules and their predecessors were less complete and certainly had less impact. I think your description of the importance of direct-connection roads is relevant to that era, in which the emphasis of loading FOREIGN empties was not prominent in American car handling. That is definitely true for 1891 and substantially true for 1908.

    But once those Rules were in place, and being followed to a reasonable degree, I think you misunderstand (or perhaps have not thought about) the Gilbert-Nelson hypothesis. It specifically REJECTS the notion that direct interchange is very important for car usage, because for free-running cars, they should be able to move, and did move, everywhere in the country. Thus they ought to be represented, within reason, according to percentage of the NATIONAL fleet. My data are largely in agreement with Gilbert-Nelson, though there are some discrepancies.

    I did mention that you expect SOME bias to Gilbert-Nelson due to friendly or unfriendly connections. We know that the SP and Santa Fe tried hard not to load each other's cars, but returned the empties to interchange, just to cite one example.

    The fact that I model a branch would only be a distorting factor if it is a branch with significant traffic which is out of the ordinary, such a branch on which coal or helium or pickles were produced. I do model a lot of perishable traffic--not out of the ordinary in California--and not a lot of other unusual traffic.

    I would sure love to find additional conductor train books for the Coast Line in my era. There were over 1100 reefers in the sample I analyzed, a decent sample size, but as I mentioned in the post above, only 139 box cars, not terribly large as a sample. I would not draw any conclusion other than stating a general trend to agree with Gilbert-Nelson with so small a sample of box cars.

    Finally, I would mention that 1917 was during the World War I traffic difficulties, and I would hesitate to generalize about freight car data from that period, compared to any other period.
    Tony Thompson

  3. Hi there! Just getting back into HO modeling as an adult (growing up my father had a substantial layout I would run a few of my own trains on) I recently stumbled across your blog and have found it incredibly useful.

    "My railroad" has always been the SP, and I have dreams of creating a small/thin fairly linear layout with mixes of the CA coast over a pass and into Oregon (where I'm from). While a Daylight consist and a cab forward will eventually come, I've been enamored with a couple other random ideas for freight. I hope to model a range of years (due to budget and interests) roughly early 40's to early 50's, so I can have lots of steam and a couple classy diesels.

    More to point I was curious as to 50' DD Automobile box cars. I really like them for some reason, but have had a hard time finding info on them in regards to the SP. When were they used, what areas of the SP, and do you have a preferred model?

    Thanks much in advance! I look forward to the

  4. For the pre-war cars like this, the Proto2000 (now Walthers) 50-ft. DD is close for Class A-50-14. The postwar cars all have various distinctive features and either have to be kitbashed or built from resin kits. There are various stand-ins too. If you want more particulars, let me know and I can expand on this.
    Tony Thompson