Railway electrification in New Zealand consists of three separate electric systems, all in the North Island. Electrification was initially adopted by the New Zealand Railways 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 2014–2015. Electrification of long-distance services on the North Island Main Trunk (NIMT) dates from 1986. New long tunnels, for example the Rimutaka Tunnel and the Kaimai Tunnel, were operated by diesels, and the Otira and Lyttelton Tunnels have converted to diesel operation.