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
Mangaroa railway station on a tunnel through the Rimutaka Ranges. When the Rimutaka Tunnel opened in 1955, the line between Upper Hutt and Featherston then followed an alignment that bypassed Mangaroa altogether. The new Maymorn railway station on the Rimutaka Tunnel deviation was initially called "Mangaroa". Very little of the old railway formation remains between the west and east sides of the Mangaroa Valley. Cruickshanks Tunnel still exists, though there is no formal access to it and the status of public access is uncertain. The only remains of the old Mangaroa River bridge are a few wooden bridge piles. There is still a