Interesting question, Bob. I looked in Norm Cohen's Song Steel Rail the bible of railroad songs, and didn't find anything. The Southern Pacific shops near me in Sacramento were substantial, but I don't know of any songs about railroad shop work.
Last year, I visited the shops of the Southern Railway (now a great museum) in Spencer, North Carolina - no evidence of songs there, either. I've been to lots of shops that are now museums - but alas, I found no songs. Maybe locomotive work isn't conducive to singing.
-Joe-