Wairio Branch

The Ohai Line, formerly the Ohai Industrial Line and previously the Wairio Branch and the Ohai Railway Board's line, is a 54.5 km branch line railway in Southland, New Zealand. It opened in 1882 and is one of two remaining branch lines in Southland, and one of only a few in the country. A number of smaller privately owned railways fanned out from Wairio; one of these lines, to Ohai, was worked by New Zealand Railways from 1990 and incorporated into the national network in 1992.

Built at about the same time as the Riverton section of the Tuatapere Branch, what became the Wairio Branch left the Tuatapere Branch at Thornbury, where the junction originally faced Riverton rather than Invercargill, implying that the developers might have thought Riverton was going to be the region's major port. The line was built to open up new land to settlement and agricultural use and to access coal deposits. In 1879 it was opened to Otautau, and to Wairio on 3 March 1882, where it connected with private railways.

When the Tuatapere Branch closed in 1978 the Thornbury to Makarewa section became part of the Wairio Branch, and the closure of the Kingston Branch in 1982 meant that the continuation line to Invercargill section was also incorporated into the branch. This latter section of line is one of the oldest in New Zealand; built with wooden rails, it opened in 1864.

The development of private railway lines beyond Wairio was somewhat complex. The first was established not long after the Wairio Branch was opened and was a privately owned extension of a little over two miles to the Nightcaps Coal Company in nearby Nightcaps, and operated by the Railways Department. The roads in the Ohai area in 1909 were described as "unspeakably bad" in a publication of the Ohai Railway Board in 1925; although significant coal deposits were in the area, it was difficult and hardly viable to transport the coal the short distance to the railway in Nightcaps. For this reason, another line from Wairio was proposed, but delays and negotiations meant that it did not open until June 1914. This line was operated by the Wairio Railway & Coal Company (WR&CC) and it served two additional mines in Moretown, a locality south of Ohai, but like the Nightcaps line it did not provide reasonable access to Ohai's mines. Thus a third line was required.

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