Retired train writer from berlin here, I’d love to hear more stories from you…
You know… scouting, trespassing, chasing something or someone, being chased, the sounds, the smells, the "tick, tick, tick" dogs make while stamping on floor of a metro car, etc. There are specifics, of course, but the baseline is the same everywhere I have been.
Likewise the quiet moments between action when you're tucked into side tunnels, feeling the breeze and listening to distant trains rumbling by..
Turf fights?
Someone else in the thread mentioned throwing rocks, it was actually a shared hobby and a universal one at that.