Hi All,
I have been following the discussion of the USRA box cars with interest. As it turned to the roles of potential committees, MCB, AAR, USRA I thought the following would be of interest. 
I tried posting this information as an add-on to one of the threads and seamed to may a hash of it. Here it is in what I hope is an accessible assembly. 

ARA Program XM 4940. This would seem to be the name of the committee tasked with coming up with plans for box car designs for recommended practice.

The end product of their deliberations appear to be three sample cars built 6-1917. They were of differing construction but with same internal dimensions: IL 40-6, IW 8-6, IH 9-0 or 9-1. Each was built by a different builder. Would these then be the beginnings of the USRA cars? Clearly when you examine the photos, there are differences. Has anyone seen drawings which had to precede construction? How about ARA reports of one sort or another. I have not made a serious search for either.

Eric L

Marks              Builder     Construction

IC 175001       PSC?       | |/|/|/[ ]\|\|\| |

ATSF 32001    PUL         |     [ ]     |

PRR 38000     PRR         | : : : [ ] : : : |

 

Photos are attached here and to subsequent posts. Some are of a large size so they are separated.