Mangaroa railway station war. After the war the depot was a disposal site for surplus stores until RNZAF use ceased in July 1949, at which time it is assumed that the site was transferred to the NZ Army for their use. Prior to the construction of the Rimutaka Tunnel, several proposals for a tunnel under the Rimutaka Ranges to bypass the Incline section involved tunnels with a western portal to the north-east of Mangaroa station. In 1898 a survey was completed for a tunnel between Mangaroa and Cross Creek. The idea received a great deal of attention, but ultimately went nowhere as such
Rimutaka Tunnel cutting for the new formation completed and the remainder of the track laid. On Thursday, 3 November, the new line was opened and two special trains travelled from Wellington to Speedy’s Crossing to the inauguration ceremony. The deviation's ruling grade is 1 in 70, compensated for curvature. The tightest curve is 400 metres (20 chain) radius. The tunnel rises at 1 in 400 from the western portal to the highest point on the deviation, roughly halfway through the tunnel, and then descends to the eastern portal at 1 in 180. It has an internal height of 5.18 metres (17 ft)