1877 the line to Kaitoke was officially opened by the Governor,. On 1 January 1878 the line to Kaitoke was opened to the public; becoming the railhead for the Wairarapa for nearly ten months (to 16 October). Rimutaka section The Rimutaka Range posed a severe difficulty to those involved in planning and constructing the Wairarapa Line. On 1 January 1878, the Hutt line opened to Kaitoke at the western foot of the range, and a steep but manageable route with a grade of 1 in 39-40 was found from Kaitoke up the Pakuratahi River valley to the site of Summit station, above sea level. However, from Summit down the eastern slope to Cross Creek near Featherston, a gradient of 1 in 14-16 was required. This was far too steep for regular steam locomotives to handle, and accordingly the Fell mountain railway system was employed. This used a centre rail to which specially-designed locomotives and brake vans clung, allowing them to climb the steep slope upwards or control the descent. Despite the terrain, construction of this unique route was completed swiftly, opening to Featherston on 12 October 1878. South Wairarapa section Construction from Featherston to Masterton across the Wairarapa plains north of Lake Wairarapa was relatively easy. The decision was taken to bypass Greytown and build the line through Woodside to bridge the Waiohine River at a point far enough up the river to be considered safe; a line through Greytown would have required a bridge at a point considered unsafe by the surveyors. The Greytown Branch was constructed from Woodside, and Greytown was briefly the effective terminus of the Wairarapa Line from the opening of the branch on 14 May 1880 until the bridging of the Waiohine a month later. Later in 1880, the line opened all the way through to Masterton. North Wairarapa section The northern Wairarapa was more rugged and isolated, and construction was slower and more difficult. Mauriceville, north of Masterton, was reached on 14 June 1886, followed by the next to Mangamahoe on 10 January 1887. The between Mangamahoe and Eketāhuna included the long Wiwaka tunnel, the only tunnel between the Rimutaka Incline and Woodville, and the section was opened on 8 April 1889. Construction of the section to Newman was inexplicably slow, not completed until 1896. Pahiatua was reached in May 1897, including the Mangatainoka River bridge, the longest bridge on the line at .