Kaimai Tunnel Kaimai Tunnel The Kaimai Tunnel is a railway tunnel through the Kaimai Range in the North Island of New Zealand. Since it was opened in 1978, it has held the title of longest tunnel, at 8.879 kilometres, in New Zealand, assuming this distinction from the previous title holder, the Rimutaka Tunnel. It is part of the Kaimai Deviation, which was constructed to bypass the old route of the East Coast Main Trunk Railway through the Karangahake Gorge (part of which has been preserved as the Goldfields Railway). The Kaimai Deviation is a 24 km line between Waharoa and Apata, including
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