On a windy day last week in the yard a double decker trailer c+e ,was being unloaded while the chap was on the floor pulling a pallet truck full of stuff ,the wind rocked the trailer a freezer box rolled off the top deck and came crashing down to earth,lucky nobody was hurt,but the tail lift was mashed,so be carefull with em!!! 
(them big green boxes on wheels for frozen food).