I got an ugly graphic error. When I build rail track on snow terrain and this tiles changes later to summer graphics then the track disappear. The same effect I got when I build the track in summer and after that the first winter began.
Experimental 10.1
Pak128.Britain 0.8.1
On the screenshot you can see that it is a display problem. The track is really there but you can't see it.
Usually rotating the map should help. Nevertheless, its a bug.