Standard ocean containers ( ISO spec ) are very flimsy; most of the structure is in the corner posts and, to a lesser degree, the floor. All dry box containers have wooden floors, the standard floor being sheets of plywood and none too durable. The " Heavy Floor " container uses harder wood strips with extra floor stringers underneath.
ISO standard " Flat Rack " containers actually have collapsable end bulkheads that fold down into indents in the wooden deck. An empty 40 foot flat rack also weighs 10k or more, and are expensive to own so they are somewhat rare. As noted above all ISO shipping containers are only 96 inches wide, except for non - ISO standard 102 inch wide captive fleets used in Alaska service. Alaska Marine Lines / Lynden Transport does have true flat deck " containers " in 20 foot and 40 foot lengths; they are moved from the side with a BIG forklift.