Otira Viaduct
The Otira Viaduct is a large road bridge to the south of Otira, between Otira and the Arthur's Pass summit. Completed in 1999 by McConnell Smith Pty Ltd, the four-span viaduct carries State Highway 73 over a stretch of unstable land, replacing a narrow, winding, dangerous section of road that was prone to avalanches, slips and closures. One person, Tony Western, 25, was killed during construction in July 1998 when a chain failed and a pump fell on him. A plaque was installed in his memory in the base of the westernmost pier.
Description
The Otira Viaduct is a four span cantilever bridge with a length of and average grade of 12% on its deck. Each pier is about high, supported on excavated cylinders which are in diameter and deep.History
Old coach road
Construction of the Ōtira Gorge and Arthur's Pass road began in the winter of 1865 and, until completion of the Viaduct, was a dangerous section of highway. From the summit of Arthur's Pass to Otira, the highway descends in the short distance between them. The pass was constructed in 10 months and the original coach road was opened in March 1866. The construction was completed during a harsh winter for the pass, which receives an annual average rainfall of between and, in addition to regular snow and minimum temperatures well below zero. Throughout the construction, many workers were drowned in flooding rivers. This included six workers drowning in the same week.The former coach road included 11 bridges with a total length of and five 360 degree bends through a dangerous zig-zag section. Construction was carried out by contractors J. Smith and E.G. Wright using labourers with picks, shovels, wheelbarrows and two-horse drays. The road was constructed and designed under the authority of the Canterbury Provincial Council by engineers Edward Dobson, George Thornton, and Walter & Edwin Blake.