SHoP unveiled their design for the 32-story B2 tower in Brooklyn’s Atlantic Yards last November, which will be one of the world’s tallest prefab building if all goes according to developer Forest City Ratner’s plans. Now, however, Atlantic Yards Report noticed the tower’s planned groundbreaking target, originally set for early this year, won’t be moving dirt until the end of 2012, after the adjacent Barclay’s Center arena (also designed by SHoP) opens in September. In the meantime, the developer says it’s working with unions on the details of the tower’s modular design.