Flatcar

Aircraft parts were hauled via conventional freight cars beginning in World War II.

The "Sky Box" consists of a two-piece metal shell that is placed atop a standard flatcar to support and protect wing and tail assemblies and fuselage sections in transit (originally, depressed-center or "fish belly" cars were utilized).

They are essentially bulkhead flatcars that have been reinforced by a longitudinal I-beam, often in the form of a Vierendeel truss, sometimes reinforced by diagonal members, but originally in the form of stressed panels perforated by panel-lightening "opera windows", either oval-shaped (seen above) or egg-shaped.

Loads typically handled include electrical power equipment and large industrial production machinery.

Some companies, such as CSX Transportation, have former wood-carrying flatcars rebuilt into platforms which mount remote control equipment for use in operating locomotives.

Such platforms are fitted with appropriate headlights, horns, and air brake appliances to operate in the leading position on a cut of cars (i.e. coupled ahead of the locomotive).

Indeed, when the first well cars appeared, allowing double stacking, many container flats were re-built as autoracks.

The few "new build" container flats are identifiable by their lack of decking, welded steel frame, and standard 89-foot (27.13 m) length.

The ATTX cars, which feature non-sparking grips and sides, are built for hauling dangerous goods (ammunition, flammable fluids, etc.).

One notable type is Canadian Pacific Railway's XTRX service—dedicated five-unit flats that only carry trailers.