The construction of the South Rangitikei Bridge was the first link in the new rail route of the Mangaweka railway deviation. The 7 kilometre Mangaweka deviation, opened in 1981, was a realignment of the North Island main trunk railway completed in 1908. The new route moved the line away from unstable land, requiring the construction of three massive viaducts, which are among the highest in New Zealand, and are unique in their close proximity to each other.