Well, "built over with asphalt" is what I was told by a member of the draisine ride organizers on Saturday as to why we couldn't go any further than the place I marked on the map.

But I just had a second look at street level imagery, it seems it's not asphalt, the rails are just as present as in the middle part, they've just not been cleaned for driving, if you know what I mean. I'll therefore redeclare the entire track as draisine again.