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
Yimbun Railway Tunnel HC Stanley; the steel and concrete Harlin Rail Bridge over Maronghi Creek at Harlin; and the Yimbun Railway Tunnel. Approximately two dozen timber rail bridges are still intact, although their condition varies greatly. Yimbun Railway Tunnel is located between and from Wulkuraka station along the former Brisbane Valley Branch Line formation and is sited beneath a saddle between two knolls. Yimbun Railway Tunnel is a semi-elliptical, concrete-lined, straight tunnel that is long and has a gradient of 1:165 against north-bound traffic. It has an earthen floor and is approximately high at its apex. Both portals feature the date "1910". The