Class U special wagon

The International Union of Railways groups all special classes of railway goods wagon (less those in classes F, H, L, S or Z) into Class U in its goods wagon classification system.

These are:

• Bulk goods wagons for transporting powders, etc.
• Dual coupling wagons for joining wagons with different coupling systems
• Barrier vehicles for joining wagons with different coupling systems
• Well wagons, including low-deck wagons and Schnabel wagons
• Self-discharging hoppers with loading hatches
• Trials vehicles for RoadRailer and Kombirail^[1] systems for intermodal transport.

Between 1964 and 1979 bulk goods wagons for liquid and gaseous materials (tank wagons) were included in Class U before being reclassified in 1980 as Class Z.