 Originally operated by DM/D class electric multiple units and carriage trains hauled by ED and EW class electric locomotives, the carriage trains and many of the DM/D units were phased out upon the introduction of the "Ganz-Mavag" EM/ET class units in the early 1980s.The "Matangi" FP/FT class was introduced on the Hutt Valley Line in 2011–12, initially relegating the Ganz Mavag units to peak services only before being completely replacing them from 2015.Proposals have been made to extend the electrification into the Wairarapa and the Rimutaka Tunnel was constructed to allow overhead lines to be installed, although before opening diesel operation was adopted.