The Waianakarua Bridge, spanning the northern branch of the Waianakarua River in North Otago, one of the oldest surviving bridges on New Zealand's national road network, was built in 1874. With the development of farms and small towns along the route between Dunedin and Oamaru, road construction became a critical issue for locals and politicians alike. Road building progressed rapidly, quickly paralleling the opening of the main railway line in the mid-1870s. Bridging rivers was evidently one of the primary tasks for engineers, and for the provincial engineer (and later New Zealand's chief surveyor) John Turnbull Thomson, it formed a core part of his work. In his 1868 report to the Otago Provincial Council, John Turnbull Thomson, the road and civil engineer, recommended regarding bridge construction: "I wish to note that I would strongly recommend to the Government that iron or stone be used for all essential structural components, as native timber has been found to be inferior in terms of durability." Geoffrey Thornton's treatise on bridges explains how unusual this decision was. Thornton's research on early bridges in New Zealand shows that the Waianakarua Bridge is among the oldest stone arch bridges in the country. In 1868, Thomson built a four-arched stone bridge over the southern arm of the Waianakarua River to replace the existing ford. There were plans to bridge the northern arm of the river as well, and funds were allocated for this purpose under the North Otago Public Works Loan Act of 1872. Thomson was influenced by the Twizel Bridge over the River Till in Northumberland, England, near his childhood home. By October 1874, the stone arches of the bridge were complete, and it was anticipated that the approaches would be finished within a week. The North Otago Times raved that "one of the greatest obstacles to travelers" had been removed. The bridge was constructed in two spans of 18.2 m (60 ft) each, with a 4.5 m (15 ft) rise to the inside of the arch. The piers and abutments were made of low-grade granite quarried from a nearby quarry. The entire structure was grouted with Portland cement. The remaining stonework (spandrels, parapet, and substructure) was executed in Kakanui limestone. The parapet is broken up by stately and massive piers at both ends and in the middle of the bridge, which, along with the cornice, give the structure a superb overall appearance. The roadway was paved 30 cm (12 in) thick. The North Otago Times further wrote that the provincial government is "to be congratulated for the acquisition of a structure whose bold and excellent design and execution bring the highest recognition to the provincial engineering office and the construction company." In the 19th and 20th centuries, the Waianakarua Bridge spanned the river, defying floods, the ravages of time, and increasing traffic. In 1990, the engineering significance of the Waianakarua Bridge was recognized by the IPENZ Engineering Heritage Committee with a commemorative plaque. Originally built for horse-drawn traffic, the Waianakarua Bridge was threatened with demolition, as the heavy road traffic made it difficult to cross the now narrow bridge. After lengthy discussions, negotiations, and construction work (and some opposition), the Waianakarua Bridge was widened by 900 mm on each side, and the wing walls were repositioned to accommodate the new width. The bridge's parapets were removed, the individual bridge sections were numbered, and the roadway was reinforced and widened to meet modern traffic demands. The parapets were reinstalled, and the central piers were adorned with faithful replicas of the decorative elements that had weathered over time. The NZD 950,000 project was completed in April 2005, and the bridge was reopened by the New Zealand Historic Places Trust and the National MP for Otago, David Parker. In 2006, the bridge widening project, led by Transit New Zealand and Opus International Consultants, received an award as part of the New Zealand Historic Places Trust's David Cox Memorial Awards. The award recognized the preservation of the bridge's historic integrity and its significance within its historical context, which also included the adjacent grain mill. The Waianakarua Bridge, situated as one of the oldest working bridges on a national road, has been carrying road traffic between Herbert and Hampden since 2011. This historic site was registered under the Historic Places Act 1980. The following text is the original justification submitted to the NZHPT Board at the time of registration. This bridge is one of the few remaining stone bridge structures of significance. Designed by John Turnbull Thomson and completed in 1874, it is said to have been inspired by the Twizel Bridge in Northumberland. It features two large, sloping arches with worm-shaped keystones – such ornamentation was rare in New Zealand at the time. Constructed entirely of limestone, with its massive balustrades, the bridge is a testament to solid craftsmanship and outstanding aesthetics.