Or is this the Mastery reward? There is door open by 3 inches you can see inside I think it is a signal box? Near the station. Apparently Ruhr Sieg Nord has plenty of secret spots. Just the next station apparently. The first photo is the platform at Finnentrop. The detail!!
Yes it is the Mastery reward for RSN. Sadly the signalling equipment is all mothballed, presumably the line being operated from a centralised control location. It would have been a nice Easter Egg to have an actual signalling simulation hidden in the game!
You would need the whole route rebuilt then.... Thank you. I remeber someone saying the signal box on the RSN route is a mastery....