After the terrain changes from or to snow images, sometimes ways disappear. It's still there, but just not drawn graphically. I've found this to be more frequent when changing to snow images. Restarting the game will fix the bug and ways are properly drawn. What makes this particularly odd is that not all images of the same direction will change.
(http://i199.photobucket.com/albums/aa131/AEObikes/simutrans/simscr17.png)
second bug happens when signals are laid down and afterwards you try to lay down more with the auto builder tool, but cancel it. When the tool is cancelled, all signals in its path will change to both ways after a vehicle changes its status.
(http://i199.photobucket.com/albums/aa131/AEObikes/simutrans/simscr18.png)
Are you sure that this is specific to Experimental? The graphics routines are identical to Standard in every respect.
hmmm, good point.
I'll try it out on the nightly and report back.
I also just realized that 8.2 was out.