Baby bumps are big circles on the edge of the platform near the metro which are raised, ie cement to make it safe for all disabled and even children to keep from falling in. They would be raised so that people with blindness, wheelchair users, little children etc would know NOT to go over the bumps.
People have fallen into the tracks over the years , some even died. These bumps would be there to prevent it. They could ei be raised cement not as high as a curb and you could provide travel training with this idea.