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
Tunnel Railway Romney, Hythe and Dymchurch Railway. As the new railway would not be carrying heavy loads and would be travelling only a short distance, it was built as a narrow gauge railway, with a track gauge of . This allowed the new branch tunnel to be built to far smaller dimensions than the existing tunnel, at just high and wide. Although a cable haulage system had initially been considered, Ramsgate Olympia decided early in the line's planning to electrify the line. A third rail system was rejected due to concerns for the safety of the large numbers of children expected to