logging railroad types and structure.
It is time to think before you work on your plan, or letter locomotives. Lots of variations to the theme here, and you want to have a cohearant vision.
As to railroad organization there are a couple options I can think of off the top of my head. The first is the railroad is just an arm of the lumber co.: In that case the equipment might be labeled Maple Valley lumber and Milling co. The second option is the railroad is a separate entity, while possibly owned fully or mostly by the lumber outfit, It might be incorporated as a common carrier. This has advantages (you can condemn land via eminent domain), and some disadvantages ( you are forced to provide services for others along the right of way, and you are exposed to more regulation from the state. In the second case, the equipment might be labeled Maple Valley Railroad; have stations, passenger equipment, and other accouterments associated with a real railroad.
A third option is the railroad is a separate business, although possibly with very close ties to the lumber company, up to and including interlocking directors. My railroad follows this third path
Another major consideration is weather the mill is on a main line railroad or not. If it is not on the main line railroad, then there will have to be a separate interchange with the main line railroad, and tracks to connect that interchange to the mill. This track will be much more permanent than woods trackage, and might have a very different look to it than the woods track. This is the case with my railroad, where the valley Division has a ruling grade of 3.3%, and except in Harlow 21 inch radius curves; and the Mountain Division has 8% grades and 18in radius curves.
This has some advantages and disadvantages, but my railroad is essentially two different railroads (hence the Divisions). I have a place for the geared power, and there is a place for rod engines, including the 2-4-4-2's I love so well.
Now if your railroad is on the main line of a real railroad, you could have a big loop and a big staging yard, run through freight and passenger trains past the sawmill, as well as local freight and passenger service, which could be very interesting and fun. In this case, you might just have a mill switcher that would spot the flats and boxcars for lumber loading, or alternately this could be handled by a switch engine from the main line railroad (I'm thinking the mill switcher option would be more fun).
So those are my quick thoughts on lumber company/railroad operations. In any case do a lot of thinking before you lay the track.
Bill Nelson