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
Rimutaka Tunnel five-span 91 metres (300 ft) bridge across the Mangaroa River and two underpasses near Maoribank. There is a tunnel of 539 metres (1767 ft) near Maoribank, but on the eastern side where two short tunnels (220 metres (11 chain) and 180 metres (9 chain)) had been proposed through a spur it was cheaper to lengthen the line by 140 metres (7 chain) and have open cuttings. The construction of the Rimutaka Tunnel consumed: The first locomotives to work through the tunnel were the 560 kW DG class - the tunnel was too long for steam locomotives, making the Wairarapa Line