The Collingwood Street Bridge across the Maitai River, completed in 1955, is a notable engineering structure within Nelson. This bridge has technological heritage value because it is a relatively early example of a New Zealand welded steel bridge, a method introduced to New Zealand in the mid-twentieth century which became popular. Its fit-for-purpose through-truss design is also a tribute to the engineering knowledge and skill of two respected longstanding and Nelson City Council engineers: Charles Idrys Kidson (1898–1962) and Geoffrey Arthur Toynbee (1924–2010). The bridge has local historic and social importance because it is representative of the city’s mid-twentieth century growth.

Nelson’s site was chosen by Captain Arthur Wakefield (1799–1843) in 1841 and the first roads surveyed. It was quickly realised bridges were needed to aid the settlement’s development and the first one, across Saltwater Creek, was completed in October 1842, followed by a Maitai River bridge in 1843. By the mid-twentieth century Nelson had four traffic and three pedestrian bridges over the Maitai River.

Nelson’s population increased rapidly after World War Two. As a result the City Council had more revenue and began addressing its neglected infrastructure, where repairs and upgrades had been delayed because of the Great Depression and then the war. This meant when the 1877 timber truss Collingwood Street Bridge, which had survived reasonably frequent Maitai River floods, was partly washed out in 1954 they could reasonably consider replacing it.

Kidson’s engineering department was tasked with designing the new two-lane structure featuring pedestrian pathways. Kidson was Nelson City Engineer between 1939 and 1962 and made a valued contribution to the community. The bridge seems to have been designed by Toynbee, the future deputy city manager and Kidson’s successor as city engineer, under Kidson’s supervision.

The design needed to address a combination of site-specific factors, including incorporating sufficient river clearance and protective measures to reduce scour and flood failure risks, as well as maintaining good site lines for traffic. Earthquake resistance was also a consideration. After extensive analysis, a through-truss steel structure with concrete piers was adopted, rather than a reinforced concrete bridge which was a typical type in this period. Also, the steelwork was welded instead of using the traditional riveting method. This was a relatively new bridge construction technique in New Zealand - beginning from the 1940s. There are no other all-welded steel bridges, or Nelson bridges, on the New Zealand Heritage List/Rārangi Kōrero.

Nelson City Council staff began construction in mid-1954 and the Collingwood Street Bridge was completed the following year. It is 58 metres long, consisting of a main central and two flanking spans. National Road Board design approval was protracted but was eventually granted in November 1955. The central truss acts as a barrier between each lane deck, an aspect which contributed to Frederick Melrose Horowhenua Hanson (1895–1979), Commissioner of Works, describing the design as ‘an unusual one’.