Mangaweka-Utiku deviation

 

Mangaweka-Utiku Railway Deviation cover and back page

Mangaweka-Utiku Railway Deviation history pages 1 and 2

Mangaweka-Utiku Railway Deviation history and deviation development pages 3 and 4

Mangaweka-Utiku Railway Deviation development pages 5 and 6

In 1981, the Railways Department published this leaflet describing the Mangaweka-Utiku deviation on the North Island Main Trunk line. The deviation was the most significant of its kind on the railway and represented a significant improvement in the capacity of the line.  The map on the back page (first image) depicts how much more gradual the curves are on the route. 

The leaflet summarises the history of the construction of this section of line, including the steel-framed Mangaweka Viaduct, built by hand in the late 19th century. The deviation was planned in the 60s due to the steep gradients, tight curves, narrow tunnels and geologically unstable site of the original route.  The deviation was approved in 1971 and was opened on 18 November 1981.  The new route included three significant viaducts (North Rangitikei, Kawhatau and South Rangitikei).  The first two 80 and 75 metres above the river bed, and 160m long each.  The third is 80m above the river bed and 315m long.

The project was future proofed to enable the electrification which was implemented six years later.  I walked over the South Rangitikei Viaduct as a child, on a railway excursion specifically to note the opening of the deviation, and it was impressive then.