Thursday, July 13, 2023

The new Rapido SP box cars

As most Southern Pacific modelers will already know, Rapido Trains has just released a large run of two classes of SP box cars, classes B-50-15 and -16, in HO scale. Rapido has established a good reputation for well-made and accurate models, whether freight, passenger or motive power equipment. They are manufactured in China and are ready-to run. Or as my late friend Richard Hendrickson used to say, “ready to finish” (meaning weathering, improved detail, etc.).

(I should mention that at least two fine models of Class B-50-15 have been done in HO scale: Sunshine resin and Challenger brass imports, both with some variations. I will say more about those models in a following post. To the best of my knowledge, Class B-50-16 has not been done before.)

Here is a little background, drawn from Chapter 10 of my book on SP box cars, Volume 4 of the series, Southern Pacific Freight Cars (Signature Press, revised edition, 2014). In 1925, the American Railway Association (ARA) introduced a proposed standard single-sheathed box car, and a number of railroads purchased these cars. With two diagonal braces on each side of the car door, these would be a familiar survivor of the 1920s, and have been modeled by several manufacturers.

Though SP did examine the design, by building two ARA cars at Sacramento in September 1925, they were not satisfied with it. They modified the design of the underframe to make it a little beefier, increased the inside height by six inches, and most visibly, substituted a corrugated steel end instead of the single-sheathed wood end of the ARA design. The result was Class B-50-15, of which 3900 cars were built, some in company shops, most by Standard Steel Car, and the last 1100 by Pullman.

Below is an example, the last of the group of cars built with a Murphy radial outside metal roof by Standard Steel Car Co. This radial roof is one of the roofs chosen for the Rapido models (Standard Steel Car photo, D. Keith Retterer collection).

As I mentioned, Rapido also modeled the following SP car class, B-50-16. This was a very similar design, the most visible change being the substitution of Dreadnaught steel ends for the corrugated ends of the B-50-15 cars. All were built in company shops. There were just 1003 cars of this class, versus the 3900 cars of Class B-50-15. 

Below is an end view (SP photo) of one of the SP B-50-16 cars. These are Murphy ends from Union Metal Products. Note that this particular design of Dreadnaught end has somewhat squarish ribs on a fairly flat surface (some other manufacturers’ ends had much more of a continuous curvature between ribs).

But there was one other change in design between classes B-50-15 and -16. The B-50-15 design used the ARA-recommended underframe dimension of 5 feet, 0 inches from truck center to end sill. But in 1927, because of problems in some car designs with space for application of sill steps, the ARA modified that recommendation to 5 feet, 6 inches. The B-50-16 design adopted the change, and when the cars were built in late 1927 and into 1928, they had that dimension.

Relocating the body bolster 6 inches farther from the car end necessarily meant that the vertical post in side framing, an important part of the car structure and attached to the bolster, also moved 6 inches inward. In making these models, Rapido chose to change only the car ends from B-50-15 to -16, but not to modify the body and the underframe by 6 scale inches at each end. 

Does this matter to the model? In HO scale, 6 inches becomes 0.069 inches. Below is a piece of scale 6 x 6-inch styrene, shown against a Rapido model. This is how far the adjoining vertical post to the right of the white styrene should move to the left, and of course change the diagonal braces as well. (Six inches is about the width of the hat section post plus base itself, so it should move by its own width.) As I said, Rapido chose not to do this.

I should mention that there has been considerable chatter on the Internet about this point. I will just observe that examining the many photos of both classes in my book, the difference between the classes is not very visible. These six inches are hard to see consistently even in enlarged prototype photos, and are certainly not very obvious in HO scale. But the very particular modeler may decline to own this model of Class B-50-16.

Let me conclude this analysis by mentioning that Rapido chose to make the sheathing boards on the car sides wider than the prototype. On the models, there are 21 boards, top to bottom (compare the photo above); the SP prototype General Arrangement (GA) shows that there should be 32. I show the GA drawing for Class B-50-16 below (courtesy Frank Hodina). You can click on the image to enlarge it if you wish. And incidentally, this drawing shows the 5 ft.-6 in. truck-center to end-sill distance.

Doubtless one attraction of these cars to Rapido was the variety of paint schemes they carried over their service lives. Conventional freight schemes of three different eras, two different (and distinctive!) “Overnight” schemes, a passenger Dark Olive Green scheme, and in later years, an MOW scheme. Moreover, over a span of years, many cars were rebuilt with steel sheathing inside the side framing, though quite a few cars remained wood-sheathed for their entire lives. Rapido modeled both.

The entire range of possibilities, however, was not picked up by Rapido. They omitted the T&NO cars, which had the distinctive Camel-Allen doors, and all the cars with Hutchins “Dry Lading” roofs. Still, much of the variety in these two car classes has indeed been modeled by Rapido. To see the full range, visit their web page about these models (at: ). 

I will return to this topic, discussing model details and showing examples of some of the paint schemes, in a following post.

Tony Thompson


  1. Hello Tony- 15229 has a regular Murphy radial roof. The Viking roof cars did not have an inset below the roof eaves like the Murphy radial and there were also numerous carriage bolt heads along the outer face of the roof eaves just above the top of the side. Cheers, Ted

  2. Above comment is mine. Not anon.