High Quality Content by WIKIPEDIA articles! The Wairio Branch, now incorporating the Ohai Industrial Line, is a branch line railway in Southland, New Zealand. IT opened in 1882 and is the sole remaining branch line in Southland, and one of only a few in the entire country. A Number of smaller, privately owned railways fanned out from the terminus in Wairio; one of these lines, to Ohai, was incorporated into the national network in 1990.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. IT 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 then an extension to Wairio was built, opening on 3 March 1882. THis was the terminus of the government's line but not the railway itself. THe junction points at Thornbury pointed towards Riverton rather than Invercargill, implying that the developers might have thought Riverton was going to be the region's major port.