Heritage listing for unique Mangaweka cantilever bridge

The Mangaweka cantilever bridge will be open to pedestrians and cyclists.

Mangaweka’s unique cantilever bridge has been awarded heritage status.

The 120-year-old bridge, the first and only steel cantilever road bridge constructed in New Zealand, has been listed on the New Zealand Heritage List/Rārangi Kōrero as a Category 2 historic place.

Natalie Marshall, central region heritage assessment adviser for Heritage New Zealand Pouhere Taonga, said the bridge spanning the Rangitikei River sat within and complemented a dramatic natural environment.

The single-lane bridge is about 141m long. It has a timber deck and a three-span steel truss design. The bridge is set lower down from the surrounding hills and provides a vantage point from which to appreciate the natural landscape.

It also had historical significance for its association with the Public Works Department, which led its design and construction, and the highly respected engineering firm J. and A. Anderson Ltd.

“It has local significance for its association with the settlement and development of farming and forestry in the central Manawatū-Whanganui region,” Marshall said.

“The bridge’s social significance is demonstrated by strong community support for the retention of the bridge when it was threatened some years ago with demolition.”

In a flood-prone area, the original bridge’s cantilever design avoided mid-stream piers. Two concrete piers, built for a never-completed cylinder bridge, were extended to facilitate the design.

The cantilever design was rarely adopted in New Zealand and the Mangaweka bridge is one of only three known cantilever bridges in existence in the country. The others are the Waiau Ferry Bridge, built in 1887 in North Canterbury, and the Makohine Viaduct (1902), just south of Mangaweka.

In 2016, a routine inspection of the bridge revealed significant structural deterioration and it was deemed unable to meet modern traffic demands.

After public consultation in 2019, the Rangitīkei and Manawatū district councils opted to repair it to serve as a pedestrian and cycle bridge. The councils retained ownership, while responsibility for its preservation, maintenance and management was vested in the Manawatū Heritage Incorporation. A replacement road bridge 30m to the south was opened in May 2022.

The cantilever bridge is now used for tourism and recreational activities.