A mobile crane removing a concrete bridge girder goes over due to soils sluffing off down a hill. The soils are non-native and even though they used matting, you should have some sort of reinforcement to prevent the soils from moving when on a hill like this. I would recommend using a soils engineer when you get close to the edge. like this. We could be talking about 130 kips per outrigger (guessing due to size of crane) of force on soils that may be compacted, but what is holding it uphill?