Railway electrification in New Zealand Railway electrification in New Zealand Railway electrification was initially adopted by the New Zealand Railways in New Zealand for long tunnels; the Otira Tunnel, the Lyttelton Rail Tunnel and the two Tawa Tunnels of the Tawa Flat Deviation. Electrification of Wellington suburban services started with the Johnsonville Line and Kapiti Line out of Wellington from the 1930s. Auckland suburban services were electrified in 2014–15. Electrification of long distance services on the North Island Main Trunk (NIMT) dates from 1986, although KiwiRail is now considering diesel operation of the NIMT. New long tunnels e.g. the Rimutaka Tunnel and the Kaimai Tunnel
Railway electrification in New Zealand Tunnel (1955) and the Kaimai Tunnel (1978). The Rimutaka Tunnel required an intermediate ventilation shaft. From 1967 diesel locomotives (D class) replaced electric locomotives (E class) on freight trains south of Paekakariki on the Kapiti Line after the track in some older tunnels was lowered, so diesels could run under the catenary into Wellington. On two existing electrified tunnels the electrified section was only a small part of the total line. Hence the Lyttelton Rail Tunnel was operated by diesel locomotives from 19 September 1970. The Otira Tunnel was long and steep, so for dieselisation from 1997 a door and