Specification :

Railway flat wagon is a piece of railroad rolling stock that consists of an open, flat deck on four or six wheels or a pair of trucks ( US) or bogies ( UK) . The deck of the flat wagon can be wood or steel, and the sides of the deck can include pockets for stakes or tie-down points to secure loads. Flat wagon designed for carrying machinery have sliding chain assemblies recessed in the deck.
Railway flat wagons are used for loads that are too large or cumbersome to load in enclosed cars such as boxcars . They are also often used to transport containers or trailers in intermodal shipping.