Curling raises the slabs edges and corners.  This usually causes the slab to react in one of two ways.  The slab either rocks back and forth or breaks in the center, neither of which is good.



If the slab rocks back and forth as a forklift travels across it, the weight of the forklift will push down the side of the slab.  As the forklift starts to get onto the next panel, the wheels slam into the edge of the adjacent slab since the adjacent slab is slightly higher.  This impact slowly breaks down the edge of the adjacent slab.