I, too, disbelieve the metaphorical interpretation.

"I've Been Workin' on the Railroad" is demonstrably the joining together into a medley of at least two songs.   "Levee Song" is a third, if you use that, in the old style, to introduce it. And if you use "Goodnight Ladies" to end it, as has been done by college singing groups for a century or so, that's four songs.

Medley. Not a single song. That more or less removes the need to think a banjo means a shovel, Dinah is the horn, the engine, the nearby cotton gin, the hotel downtown, or any of that. She's a real woman, and she's got a working role in the Dinah song, which (to repeat) is separate and not originally part of the Workin' on the Railroad song at all.

1.   It seems clear that Dinah is cooking in a real kitchen, perhaps a shanty kitchen near the track.

2. Seems plausible that she may be cooking for railroad workers.

3. She may very well be amorous, keeping company with somebody who's hanging around the kitchen, and that's slowing up the meal, which is why the horn is late in blowing.

4. The horn she blows is the well-known dinner horn, not unlike a foghorn on a ship, audible at a considerable distance. When she blows it, dinner's ready. Or lunch. Or breakfast. Till she blows it, it ain't.

Gosh, Dinah seems complex enough without turning her into something industrial. Bet she wouldn't have stood for it if she could post a reply here.

I can't think of much good to say for medleys. They disrespect the songs they contain, which ought to be worthy of singing entire, or why were they songs in the first place. And when people forget their origins and tend to think they are a single song, confusion results ... as above.

End of rant, grrr grrr.

All hail to Dinah. And to that song about her, which I wish we knew more of.

Bob