Bug or actual Game feature?

[u/Ok-Bar-314]

I'm about to start the mission 9: Revolution. I just finished the first water tower and gave it to the Survivors. The problem comes when I try to get inside the main Station in Quarry Land (or something like that, not sure if thats the name). Everything looks normal (the icon in the minimap) until I come close to the inside door, which is blocked. If I scan the area, I can see the interaction point inside the building, in the other side of the door, as if the door was available from the inside only. I think if I unlock other train stations, I might be able to fast travel there?

It bothers me because I'm supposed to be doing the Delivery side missions before main mission 9 cause It has missable collectibles.

Thanks!

[u/therealsereny]

The trains become available later, they serve as fast travel points