 The Norwegian State Railways (NSB) took over the railway operations in 1920 when the new railway from Notodden to Kongsberg was completed.The railway ferry service was provided by four different ships, SF "Rjukanfoss", SF "Hydro" (1919), SF "Ammonia" (1929) and MF "Storegut" (1956).The three first were steam ships, and the latter two are still anchored at Mæl.