The Canterbury Provincial Council began considering possible routes for a rail link between the township of Christchurch and the port of Lyttelton about 1853. The idea was shelved because of the cost involved until 1858 when the superintendent, William Sefton Moorhouse (c1825-81), initiated it once again. George Robert Stevenson was consulted. He favoured a 10km line with a 2.6 km tunnel. He recommended an English firm of contractors, Smith and Knight of London, but this firm is said to have declined the contract when they discovered that it involved tunnelling through a volcano.
Edward Dobson, provincial engineer, had been responsible for the project since 1854. The provincial geologist, Julius von Haast, undertook exploration and site investigation, advising the engineers. The contract was finally let to Holmes and Co of Melbourne in 1861. Of the 240 000 pound contract price, the cost of the tunnel was estimated at 195 000 pounds. The contract allowed five years for construction. Construction of the tunnel began with a ceremony at Heathcote on 17 July 1861 at which Moorhouse cut the first sod and on 29 September 1862 a ceremonial stone was placed by Mrs Moorhouse.
Boring went ahead from both the Lyttelton and Heathcote ends. Gunpowder charges were used and blown materials was removed using horses. The tunnellers met on 28 May 1867. 5’6″ gauge rails were laid and the first train went through in mid November 1867. Passenger services began in December though workers continued drainage and widening by night. The tunnel remained in the contractors hands until August 1868 and it took another four years to finish lining the tunnel. From 1863 a temporary railway line had operated between Christchurch and Ferrymeade wharf.
Between April 1876 and December 1877, the 5’6″ gauge rails were replaced with 3’6″ gauge. Since this time the tunnel has seen no major modifications. The instalment of heavier rails, improved signalling, electrification (1925-28) and dieselisation (c1970) reflect technological progress. With dieselisation, the electric locomotives and substations were phased out.
Article by Heritage New Zealand Pouhere Taonga