Coaling and watering - working at height

Now, what about Water troughs?

Or new build Compounds?

 

Or employ condensing locos?

 

The condensing technology was afaik based on that applied to some Kriegsloks so presumably there must be designs for standard gauge condensing tenders somewhere

 

Short-term condensing (as used in the London tunnels) needs little more than a pipe into the tank. Long-term needs more than just an enormous tender, though that alone is a lot of complication.