Three women have been hurt by falling into Tate Modern's latest installation - a crack in the floor. At 548 feet long, up to three feet deep and 10inches wide, it zigzags the length of the Turbine Hall and has been described as a highly original work of art. But visitors have already paid the price for failing to heed warning signs. And a builder said if he had been responsible for the crack he would be sued for health and safety breaches. ... The crack is said to represent the division problem of integrating immigrants into European society.