Hi,
first of all, you're doing a great job with Experimental!
A bug in 9.11 sometimes occurs when updating tram lines, but not always. Has happened to me several times now, in different cities. A new-year-autosave is here:
http://hotfile.com/dl/123826962/d3dbc68/autosave01.rar.html
The error occurred on Jan. 10 when updating lines in Arlport. The Jan. 1 autosave contains the same routes, but probably not the same number of trams there.
To be exact, I think it happens sometimes when changing schedules for an existing tram vehicle, sending it to another route. The message ran something like "mini_vec (?) error: index 9 not in 0..4"
(Is there a logfile that saves error messages?)
Oh, and there's one thing that bothered me when I first ran experimental, beginning in 1840: in the buying menu, you see only horses and the tab showing coaches isn't visible. IIRC that behaviour is different from normal Simutrans. At first I didn't notice the new tabs appearing after buying horses and I ran a few horses-only lines. Not knowing that there *are* coaches, I thought that in Pak128-Britain, maybe people could only walk or ride to the train station...
I could reproduce it, the message reads "minivec_tpl<T>"
Thank you for the report: I shall have to look into this when I have the computer that I normally use to code/compile Simutrans available to me again.
I think that I have managed to fix this one - thank you for your report. The fix will be incorporated into the next release.