South Rangitīkei Viaduct wins New Zealand Concrete Society award for outstanding concrete structures

The South Rangitikei Viaduct has won the New Zealand Concrete Society's Enduring Concrete Award.

The world-leading South Rangitīkei Viaduct, one of the North Island's tallest and longest rail bridges, has won an award for outstanding concrete structures.

The KiwiRail bridge, the first in the world to feature innovative seismic strengthening technology, has received the New Zealand Concrete Society's Enduring Concrete Award, given every two years to outstanding concrete structures or buildings more than 25 years old.

"The viaduct was the first in the world to use a new type of seismic technology which allows the piers to step or rock in an earthquake, dissipating the earthquake's energy without causing any major structural damage," KiwiRail acting chief operations officer Henare Clarke said.

It is one of three pre-stressed concrete viaducts that were built on the North Island Main Trunk line (NIMT) as part of the Mangaweka deviation.

The deviation opened in 1981 after New Zealand Railways decided to reroute the line across the Rangitīkei River plains to cut out the steep gradients, tight curves and narrow tunnels on the NIMT between Mangaweka and Utiku.

The route crosses three major river valleys and required three viaducts to be built. The South Rangitīkei Viaduct is 315 metres long, has six spans of up to 56m and twin leg piers which rise 76m above the river level.

"This award is a tribute to those who built and designed the bridge, and to those who have maintained it over the years," Clarke said.

A bronze plaque commemorating the award will be attached to the viaduct.