The size for each waterway is limited by the dimensions of the structures including the locks and boat lifts on the route.
The larger river classification sizes are focused on the carriage of intermodal containers in convoys of barges propelled by a push-tug.
Most of the canals of the United Kingdom have smaller locks and would fall below the dimensions in the European classification system.
In 2004, the standards were extended with four smaller sizes RA–RD covering recreational craft, which had originally been developed and proposed via PIANC.
[2] The proposal to add the recreational sizes was adopted by United Nations Economic Commission for Europe resolution 52.