Also @bxlf the access tag is not only because of "trunk" itself but rather because it's unsafe to drive there. The tag motorroad=yes holds legal value (autoweg sign). Trunk is a classification osm gives!, often to autoroads but not always. This piece is not an autoweg. Further down B101 it is. 
Regardless often on major highways, it is manually signposted that pedestrians are obviously not allowed to go.