I saw a coal mine plan which had 3 tracks. The 3 tracks under the loader were filled with loaded coal cars. On the arriving track there we 9 cars with empty hoppers. The plan showed how to switch them out and exchange them.
I saw it posted about a year back, but the link I cached is dead.
The train pulls all the 9 loads (which are sitting 3 cars in each track, 1 under the loader and 2 below the loader and sets them over to a track. The train then spots the empties, putting 3 cars in each track, 2 above the loader and 1 under the loader. The train departs.
The mines load the cars under the loader, then pull or roll down the next empty car in each track. They load the middle car in each track. They pull or roll down each track to the last empty car. They load that car. The mine now sits with 3 loads in each track, 2 below the loader and 1 under the loader.
Coal mines with multiple loading points usually shipped different-sized coal: a different size at each point. Therefore, it would be coincidental that the same number of railroad cars were loaded at each point.
Yeah, it is not a terribly realistic coal mine. More a demonstration that it should be technically feasible to swap quite a few cars around in a smallish foot print at the end of a small branch line.
Speaking about realistic coal mines - I seem to recall that there was a very cool web page somewhere on modelling realistic appalachian coal mining/coal train operations.
Ah, found it - had to cast about for a couple of different search terms before google could locate it. This one has quite a few more realistic track plans for mines, plus tips on operations:
The best source of information on track plans for coal mines I’m aware of is the ten-page article by Hilary Smith in the December 2006 Layout Design Journal (LDJ-35) (contact sales@ldsig.org). Tony Koester’s book The Model Railroader’s Guide to Coal Railroading (by Kalmbach) is very informative, but it has a deficit of track plans.