From programming the source code I have learned a few tricks, including making the rendering of rail tracks and the appearance of MGOs conditional. A couple of days ago I added some rail lines to my "Little Bob" theatre, which s using the "Smooth hilly" height map. Some of the tracks ran up quite steep hills, and it brought the possibility of tunnels into play.
The upshot was a new exe with code that made it only display the track and the train if the height was below a set maximum.
It actually worked, but there is no tunnel graphic and if there are bends in the track it is very difficult to find where the track and train will emerge.
The trains and tracks actually reappeared out of hillsides, but miles from where they entered.
It is totally impractical, but I got a kick from being able to get it to work.
The spin-off is that today I did more work on the railway editor, getting it to use a height map, so that the tracks can be located so that steep hills are avoided
