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Monday, July 18, 2011

Choosing a model car fleet-SP box cars

As I’ve described in earlier posts, my approach to my model car fleet is to start with the proportions of prototype car fleets. This becomes particularly relevant with the car owners which are represented on my layout with numerous cars, namely SP and PFE. I discussed the issues involved in the PFE fleet for 1953 back in December (see: and in this post, I describe the corresponding issues for SP box cars. (Other SP car types may be similarly treated, but in the early 1950s the SP fleet was about 57 percent box cars, so these are by far the biggest part of the topic.)
     I might begin with 40-foot box cars of AAR design. SP bought an awful lot of these (more than 22,000 cars), in their various permutations, from 1936 until 1953. My starting point, then, is the prototype roster. A full roster is available in my book on SP box cars (Southern Pacific Freight Cars, Vol. 4, Box Cars, Signature Press, 2006) and an abbreviated version, including car number series, is in my clinic handout on Google Docs. Here is the link:

As with the PFE fleet described in the post cited in the first paragraph, above, I plan to roughly proportion my SP box cars at one model per 1000 prototype cars. Then a simple listing of the sizes of car classes shows directly how many models I need of each car class. Here is a table of the ones I’m talking about.

The right-hand column shows “needed model cars” Where denoted with two numbers, they represent “SP, T&NO” respectively. It will be noted that one cannot exactly choose one car per 1000 prototype cars for car classes with 1500 cars, which is why the table shows entries like “1 or 2” in some cases.
     What this table doesn’t show is what physical models are needed for the various classes, but the six “body styles” which describe these 14 classes and 22,300 cars are listed in the clinic handout, available in the Google Docs link shown above.
     One can immediately note in this list that the cars following Class B-50-26 were quite numerous (more than 7800 cars). The bad news is that there is no styrene model correct “out of the box” for any of those classes. There are Sunshine resin versions of both B-50-27 and B-50-28 classes (and classes B-50-29 through -33 were very similar to -28), and various styrene models can be kitbashed simply to yield this car body (see below), but there is no correct styrene model.
     Why not? What distinguished these SP box cars from others being built after World War II? It was the car height. For its own reasons, SP continued to buy (or build at Sacramento) cars with 10 feet interior height (IH), while practically all other railroads went to 10 feet, 6 inches IH after the war. Well, what’s six scale inches between friends? I’ll agree that in most situations, 6 scale inches is insignificant in HO scale, but in this case, it changes the appearance of the car end, removing what would be the top rib on the end of a 10' 6" box car.
     Many modelers won’t care, which means that conventional models of 10' 6" postwar box cars can be acceptable stand-ins for them. Unfortunately, I’m not in that group. On most railroads’ box cars, I certainly try if possible to get things like car ends right, but the SP is not “most box cars” for me; instead, it’s more a case of “must be right” unless the modeling demand is excessive.
     I said there is a simple kitbash. Here it is. Take any 10' 6" postwar box car, with correct roof for the SP car class desired. (If the roof is a separate part, glue it on.) Then use a razor saw to slice off the roof and top of ends right at the eave line, taking care to keep the cut neat. Gently sand the two cut surfaces to clean them up, and re-attach the pieces with styrene cement. The saw kerf has removed almost exactly six inches of height, and all or most of the original top rib on the end. You now need to add the correct top rib, if any, and voila, you have a pretty good 10' IH car.
     Here is a photo of a B-50-27 car created this way, starting with the old C&BT Shops car kit, shortened as described, and then replacing all, and I do mean all, of the clunky detail parts provided in the kit with aftermarket freight car parts:

The top rib on the end is styrene strip, and a 7-panel Superior door has been fitted. The same process works with other postwar box car models. Incidentally, the idea for this process came from Richard Hendrickson, who had already performed it and convinced himself it would work. (Then he had to convince me that it would work.)
     Where am I with my own SP box car fleet needs? Naturally, I have too many of some classes and too few of others. My intent is to correct these existing imbalances gently, because the table shown above is only a guideline. But in acquiring additional SP box cars, the table, combined with my current roster, does show me exactly what (and what not) to buy.
Tony Thompson


  1. What is the quantity of box cars (or 40'box cars) you are allowing for your layout? I suspect you are allowing the SP 40' box car fleet to be about one third of your total fleet. The 40' and 50' fleet becomes very key to your total fleet. I am looking forward to your future blogs on this topic.


  2. There is not a fixed number (yet) for 40-foot box cars. As you suggest, I do intend to have around one-third SP cars among them. In addition to the car classes listed in the post we are discussing, there are the cars which came before the 1937 AAR cars, and as you mention, the 50-foot cars, which I separate into the single-door and double-door (automobile) cars. These will indeed be the subject of future posts.
    Tony Thompson