For your protection
Doris Salcedo's Shibboleth at the Tate Modern "asks questions about the interaction of sculpture and space, about architecture and the values it enshrines, and about the shaky ideological foundations on which Western notions of modernity are built. In particular, Salcedo is addressing a long legacy of racism and colonialism that underlies the modern world."
Due to a bunch of people falling into the gash (though IMHO you'd have to be trying quite hard to get anything stuck in there) they've now put up a safety barrier. There's probably a deep sociological point to be made there, about people being prevented from hurting themselves on artistic points about racial schism. But I can't summon it.
Mind the gap.