	New Zealand Co-operative Dairy Company started mining at Glen Afton in 1921. The 2.5 km extension from Rotowaro to Pukemiro and Glen Afton was built between 1915 and 1924, although a further proposed extension beyond Glen Afton did not proceed. The hill section from Rotowaro to Glen Afton was difficult to construct, with a large "summit" cutting just before Glen Afton. Grades on the hill section were up to 1 in 50, with 150m (7.5 chain) radius curves. At the same time as the extension, tablet signalling was introduced between Huntly and Glen Afton.