Doh, gee, Mark, when I go out, all I see are steel running boards. So I guess
they were always steel. (Using your logic.)

I never said wood was NEVER used. The question was WHEN wood was replaced with
steel. Safety requirements change. Steel was MANDATED for new box car and reefer
running boards in the 1940's for example. I really have no good photos of tank
car running boards (not platforms) of cars built in the 1940's, and some 1940's
drawings do call out AAR steel running boards. But Tony is right, the Type 27
must have had wood running boards in 1927, and for some time afterwards.

As for drawings of cross sections showing "grain" ... As someone who once had a
job drafting engineering drawings for Trident submarines, I can tell you that a
piece of steel shown in cross section often received diagonal stripes simply to
indicate that you were looking at something that was solid, and not a rectangular
tube.

As for APEX running boards being 1" thick -- Yes, they were, on BOX CARS. It says
so right there in the CBC drawings. Other thicknesses existed for other applications.
On box cars the unsupported span was 41".

Some tank car platforms were treadplate steel. I thought it was possible that this
was used for running boards. But as I said, good running board photos of 1940's tank
cars are really hard to find.

Tim O'Connor