Era of public works
New Zealand’s technical and engineering industry expanded in the years after the Second World War, driven by an unprecedented public works programme.
Projects included realigning and sealing roads, building motorways, and constructing a range of hydroelectric schemes. Expertise and equipment was imported or developed in New Zealand and some of the work was pioneering.
Cook Strait cable
One of the most innovative projects was the link from the hydroelectric station at Benmore on the Waitaki River to the Haywards Hill distribution station in the Hutt Valley. The project, proposed in 1950 by the State Hydro-electricity Department, was designed to exploit southern hydroelectric potential and bring power generated to the North Island.
Engineered by the Electricity Department, the underwater cables were the first to be gas-pressurised. At the time, the cables across Cook Strait were the longest, heaviest and had the greatest capacity of any ever made, and at 535 kilometres, the whole high-voltage direct-current (HVDC) cable was the longest of its type in the world.
Some engineering works such as hydro schemes were affected by a growing awareness of environmental issues. Plans to build a major power station on Lake Manapōuri in Fiordland, raising the lake level and destroying the original ecosystem, provoked significant protests in the early 1970s. The station was built without the lake being raised.
Developing ports and rail
Other engineering work was more mundane, reflecting the expansion of the population and the economy. An export boom – especially in wool – prompted harbour boards around the country to develop port facilities. A system of all-weather loaders was introduced at Bluff from 1953. Napier Harbour was deepened and wharves added, and the Mt Maunganui deep-water port was developed.
In 1980 the government approved an upgrade of the North Island main trunk railway line which cost $260 million over four years. The line through the rugged central section was electrified, the track realigned, and tunnels ‘daylighted’ (opened up). Some older viaducts were bypassed or replaced. The refurbished line was able to carry 50% heavier trains, and there were potential annual savings of 20 million litres of diesel fuel.
Auckland Harbour Bridge
The Auckland Harbour Bridge spanning the Waitematā harbour was built between 1956 and 1959. The bridge is 1.2 kilometres long and is a significant landmark. In 1968 work began on ‘clip-on’ extensions which added four new lanes. In 2016, 168,500 vehicles crossed the bridge on a typical day.
Late 20th century reforms
The economic restructuring and diversification of the late 20th century closed down some of New Zealand’s more traditional engineering fields. But the range and scope of the local engineering industry was extended.
Before Te Papa was built its waterfront site was occupied by a 3,175-tonne, five-storey hotel. Rather than let it be demolished, the hotel’s owners put it on rails and moved it a short way along and across the street. Renamed the Museum Hotel, the building arrived in perfect condition and less than one centimetre out of line.
Te Papa Tongarewa
Perhaps the most challenging building was the Museum of New Zealand Te Papa Tongarewa. At 120 x 190 metres, and five storeys high, it is a large structure. It was built on reclaimed land in an earthquake zone.
Development began in 1988. Design specifications required a structure that would last up to 150 years. Special base-isolation systems were developed for the foundations, which are able to move up to 400 millimetres in an earthquake. The building opened in 1998.
Auckland Sky Tower
The top of the mast of Auckland’s Sky Tower, built in the early 1990s, is 328 metres above the ground, making it the tallest free-standing structure in the Southern Hemisphere. Although Auckland is not an earthquake zone, special attention was paid to earthquake-proofing. The tower was designed to resist 1-in-1000 year gusts of 200 kilometres an hour.