Southern Pacific Switching Layout

[Green_Elite_Cab]

Well, would any railroad ever keep an engine on a busy industrial spur?

And if so how would it operate? I am thinking something like this:
(Please excuse the bad drawing :oops: )

Yes. In fact, if an industry is busy enough, it will probably have its own locomotives, that do all the major switching and then the larger railroads just pick up the outbound cars set out for them. this saves money.

Large complexes like the Oil refineries in northern New Jersey, or the Kraft Food factory in Dover, Delaware, have their own switchers (the latter operates a 44 tonner, i think).

Small shortlines like SMS Lines, and Cape May Seashore Lines definitely do this, even though they are shortlines and not "industrial" railroads.