Well, I'm really embarrassed. When I went looking for info during the original discussion, likely without my reading glasses, I saw the tables and just assumed they were something useful, like span tables. Now that I just scanned them, I see they are only "weight per 100 sq. ft." which is no help at all as far as design is concerned. Anyway, here is what was published in the 1953 Car Builder's Cyclopedia. I've included the Keystone product.

Let's see If I did these images correctly...

Chanarch2 by soolinehistory, on Flickr

Chanarch1 by soolinehistory, on Flickr

Keystone by soolinehistory, on Flickr

Dennis, not what I was hoping for but thanks for posting. Weight load by span would allow you to determine the equivalent gauge of standard corrugated steel. I wonder if there was a patent application for chanarch?

With those catalog pages, you have everything needed to calculate load bearing, span and deflection - material, thickness and profile. You know the maximum span required based on your needs. A structural engineer or a civil or mechanical engineer with a bit of structural in their background should be able to calc it.

I know, I was disappointed when I realized they were only tables of the material weight. Who in the heck thought they needed all that tabular information for the weight of the material?

I think researching the old material may be going about this backwards. What you really need to determine is the design floor loading; everything else flows from that. You would think this is included in the basic bid specs for every lot of commuter and rapid transit cars manufactured over the last four or five decades, so should be available somewhere.

More difficult is going to be picking a factor for allowable deflection, since we really don't know how any of the available composition cement products are going to hold up to flexing. Is anyone even still using composition cement floors in new rail cars, or has it all gone over to some pre-manufactured composition board product?

I think you are looking in the wrong place with corrugated products. Corrugated sheets are maximized to give just enough stiffness to withstand wind loads, etc. The sheet material never comes any closer to aligning with the load than 45*. Much better to search steel decking, as is used on roofs and under concrete. These typically have a cross section similar to the Keystone material shown above. The problem with steel decking is there is little height constraint in building construction, so all the products typically have a depth around 2" / 50mm, about three or four times what is needed for railcar use.

I did, however, run into a manufacturer that advertises that they can do specials on their 34 foot long CNC press brake. And that leads me to wonder, since I wouldn't think you need lengths longer than ten feet, if just sending the Keystone drawing out to a local shop that has a CNC brake wouldn't get some reasonable quotes, and you can get any thickness steel you want.