NZRM Volume 10 covers all railways in North Otago and part of South Canterbury on the East Coast of the South Island. There is approximately 500 km of mainline trackage within this volume. As at September 2024 only a part of Volume 10 has been fully mapped and this article will be updated as further resources come to hand.

Main South Line

The Main South Line originates at Lyttelton (Christchurch) and runs all the way south to Invercargill. MSL history starts with the Canterbury Provincial Government’s construction of New Zealand’s first public railway between Ferrymead (east Christchurch) and the City to serve a temporary port on the Heathcote River; it opened 1 December 1863. Simultaneously work began on the Lyttelton Tunnel and on completion of the associated section of line on November 1867, the Ferrymead route closed. From Christchurch the line was extended south, reaching Rolleston in 1866, then to Selwyn in 1867 and Rakaia in 1873 following the opened of the longest bridge in NZ, the 1.6 km combined structure across the Rakaia River. This was the southernmost extent of the Canterbury Provincial Railway (67 km) and was all built to a broad gauge of 1600 mm. Between 1874-1876 it was converted to the standard New Zealand gauge of 1067 mm and with the abolition of the Provincial Government of Canterbury, it became part of the national railway network. The line reached Ashburton in 1874, Rangitata North in 1875, and Temuka in 1876, where it met existing construction that had been built north from Timaru the previous year. To the south of Timaru, the Main South Line opened to St Andrews and Makikihi in 1876, and Waitaki North in 1877, where it met the line that had been built north of Oamaru reaching Waitaki South in 1875 and Waitaki North in 1876 with the completion of the long combined bridge across the Waitaki River. The Main South Line was also extended from Oamaru south to Hillgrove in 1876, just short of the halfway point, and then reached Waikouaiti in 1878.

Construction of the Main South Line was also carried out both north and south of Dunedin from the early 1870s. Heading north, the section to Port Chalmers was built on behalf of the Otago Provincial Government opening in 1873. Progress thereafter was slow due to the hilly topography of the area, with the extension to Waitati opening in 1877 following the construction of a lengthy tunnel at Mihiwaka. The following year the line joined up to the line from Christchurch at Waikouaiti. South of Dunedin further hilly country required two major tunnels and it reached Abbotsford in 1874, and then with much easier country south of Wingatui, the extension to Balclutha went ahead rapidly, opening in 1875. It reached Clinton in 1879. Meanwhile construction north of Invercargill had commenced in 1875 and reached Gore the same year, then extended to Clinton in 1877. The Main South Line was therefore completed from Christchurch to Dunedin in 1878, and from Christchurch to Invercargill in 1879, a sterling effort for the erection of 601 km of track in only 16 years, or an average of 37 km per year.

The Main South Line has been improved mainly by duplication and minor realignments in its 161 year history. The entire line between Heathcote and Rolleston was duplicated from 1878 to 1909, and most of this is still in use today except for a short section near the old Christchurch station and several km between Islington and Rolleston. Lyttelton to Christchurch was also electrified in 1929, but it was dewired in 1970 following dieselisation. A more substantive work was the Dunedin-Mosgiel duplication project of the 1910s which replaced both of the tunnels at Caversham and Wingatui with new double-track bores and took the opportunity for considerable easement of grades and elimination of all level crossings in the section. Some realignment and doubling works were also constructed between Dunedin and Port Chalmers, but although a double track tunnel was brought into use at Sawyers Bay in 1948, the second track north of Dunedin only ever reached St Leonards. The sections from Dunedin to Mosgiel and Ravensbourne to St Leonards, were singled between 1984 and 1991 due to reduced traffic volume.

Maps are now available for the Dunedin-Mosgiel section of the Main South Line. Click here to download them.