After staring at this longer, I think I understand what happened. There used to be a way as part of the railway=disused. Then a stream crossing this railway was added and this section of the way was split off and tagged as a track and a bridge. However that's not correct. I see no reason to tag this as a track. And I see a tunnel under the rail line. In fact the stream is split into two and there are two tunnels. So, I'll
* remove track, bridge and layer
* add the two tunnels and streambranches
* I'll leave the split of the railway line, since I have the feeling re-merging it now will make the edit history even harder to understand
