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
Otira Tunnel tunnel in the world and the longest in the British Empire. The Midland Railway Company investigated options to a long tunnel; but a line over the pass with gradients of 1 in 50 on both sides was not practical. Other options for a line over the pass were a cable-hauled system or a line of 1 in 15 gradient using either the Fell system or a rack railway using the Abt system (or even a S-shaped tunnel under Mount Rolleston). However the government did not favour the Fell system as used on the Rimutaka Incline which was expensive to operate.