The flat car handles cargoes of all sizes and shapes, and most flat cars are
free-running, meaning they are readily confiscated for loads wherever needed.
But it has to be recognized that flat cars made up a mere 3 percent of the national
freight car fleet in 1950 (only stock cars, at 2 percent, were lower). Accordingly,
flat cars from throughout the U.S., though plausible on the west coast, should
be relatively rare.
At the same time, it must also be remembered that SP’s freight car fleet
contained fully 10 percent flat cars, far above the national average, and should
accordingly be strongly represented in any model SP car fleet.
Specially-equipped cars or specialized cars such as depressed-center cars, are
likely to be in assigned service and, if unloaded on the SP from other parts of the
country, are likely to return to their owners empty. But general service cars,
mostly FM designation, are far more common and ordinarily may be confiscated
for loading.The most voluminous traffic on the SP for flat cars on the Coast Line in 1953 would have been lumber for the building boom in Southern California and elsewhere in the West. Most of it came from Oregon and northern California. Because of the vital need for cars in the loading areas, SP purchased considerable numbers of flat cars to ensure that an ample supply would be available. Thus most rough lumber should travel on SP cars on my layout. But it must be kept in mind that finished lumber mostly traveled in box cars, particularly double-door cars (though the AAR classification for such cars is “automobile cars”), so flat cars cannot represent all lumber traffic.
In terms of flat cars, then, my layout needs are for a strong contingent of SP’s most numerous postwar flat cars, Class F-70-7, which fortunately are available in a very accurate model from Red Caboose. I have several and will eventually have six altogether. Some day some bright manufacturer will recognize the pent-up demand for Harriman flat cars by both SP and UP modelers, and I will be able to add a couple of 40-foot cars of that distinctive straight-side-sill style. Beyond SP reporting marks, a car or two from T&NO and SSW would also be suitable.
Other roads represented are likely to be either Western road cars, not too far from home, such as GN, NP, ATSF, UP, etc., or cars from the largest national railroads, such as PRR, NYC, or B&O. It may be appropriate to plan for one car representing each of those roads for the time being.
I believe the relatively rare cars, such as depressed-center or four-truck heavy duty cars, should be equally rare on my layout, and would only operate occasionally. I have one of the Walthers 90-ton GSC drop-center cars, which is accurate for a NYC car, and will likely add a PRR well-hole flat from the F&C resin kit I have for a Class F33 car. These will be used for special loads.
The photo below show a pair of “plain Jane” SP flat cars, the essential Red Caboose 53' 6" cars, rounding the westward curve into Shumala on my layout. Decks are well weathered using acrylic paint (SP did pressure-treat flat car decking, but not with creosote), and also distressed with some gouging and cutting with a hobby knife before weathering — something more convincing in HO scale on a plastic deck than on a “real” wood one.
A major need for these and other flats is good lumber loads, and I have several under construction. Beyond that, the load possibilities for flat cars are almost endless, and one almost needs more restraint than anything else in choosing loads to model.