The reason? For my amusement and others.

As I said, the gps will not be able to calculate ETA for my journey since the map doesn’t know the max allowed speed of the track ot the max allowed speed of the train (which of course can be lower than the max speed of the track). But that is not important, when I drive the train I have the timetable to follow.

But if the track is routable the gps WILL be able to calculate the SHORTEST route (which in most cases also is the fastest). The GPS will also be able to tell me the distance to target along the track and it will be able to draw the route on the map.

The connecting nodes of the different lines ARE already connected in OSM. And since the railways will be the ONLY roads in my railway map, the shortest route WILL be along the track.

So, what do I need to do to make the railroads routable?