Components of a basic steam engine service facility:
Enginehouse/roundhouse to store engines not in use or being worked on. Steam engines are not really supposed to be left outdoors in bad weather, so they were for both storage when not in use and minor repair.
Turntable to turn them around.
Coaling tower (or big wood bin, if your engines are woodburners, or oil spigot, if your steamers burn oil.) Considering you are modeling the Northcoast, you’d be using wood or oil rather than coal.
Water tower, to refill water tanks. Water towers are also found generally once every ten miles or so–steam engines use a LOT of water.
Sand tower, to refill sanding dome
RIP track (Repair-In-Place) for minor repairs
A pit track–essentially a pit between the tracks–for engines to dump ash from the firebox and where crews can work under the engines to scrape out a***hat can’t be dumped (as you might guess, an extremely unpleasant job.)
Yard office/ready room building where crews can hang out and the shop foreman works, as well as for engine hostlers (crews whose jobs is to move engines around a service facility.)
A couple assorted shanties/sheds to store equipment
If it’s a major facility you could also use shops buildings, transfer tables, and lots of repair tracks but for a “drop your freight off and stock up” type place you won’t need more than one outside track with some rusty parts and tools around it to represent a repair track for light work.
What happens when you stop: Engine disengages from train and moves to servicing facility. If the engine is going to start back up soon, fill water tanks at tower and load up on fuel, engineer and fireman check fittings and do some periodic lubrication with a tallow-pot (an oil can.) Fill up sand if needed, change crews if it’s time to do that, turn the train around if it’s at the end of the line and has to go back the other way.
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