I see these every time a bicycle path intersects with any kind of car or train infrastructure. It just seems really patronizing, as if we’re not capable of slowing down without getting off the bike; it also shifts responsibility onto the cyclists if there is a crash based on something arbitrary (mounted vs dismounted).
Ah, the cities that feel putting up a few ‘share the road’ signs (in seemingly random locations) is a suitable replacement for having protected bike lanes.