Some of New Zealand’s major national engineering projects in the 20th century were undertaken to meet the growing demand for electricity. The use of electricity in manufacturing and industry was well established by the beginning of the century, and electrical engineers became vital.
Plans for new power stations to supply electricity to different parts of the country were brought together in the 1920s in an overall scheme for a national grid. Dams and hydroelectric power stations provided significant engineering challenges.
Civil to military engineering
The Dansey brothers of Ngāti Tūwharetoa served with great distinction in the First World War as soldiers and as engineers. Harry Dansey, believed to be the first Māori engineer, was made responsible for railway construction and transport in II Anzac Corps’s sector, including evacuation of the wounded. Roger Dansey was responsible for organising light rail operations, and then spent most of the 1920s assisting with the rebuilding of war-torn Belgium.
The Arapuni power station, built on the lower Waikato River, produced one of the trickiest problems. Engineers disagreed so strongly over the type of dam that should be built that the government formed a committee of engineers to make the decision. The station opened in 1929, but it had to be closed again the following year when a block of land about 600 metres long, 46 metres deep and 122–244 metres wide slumped. The powerhouse tilted and water ran down the face of the excavation. The lake was drained and the bed sealed before the station opened a second time in 1932.
Engineering of a different kind drew New Zealand attention in 1931 when a major earthquake devastated Napier and Hastings. This prompted new building regulations, including guidelines for the use of unreinforced masonry which had caused many deaths in Napier.
When the Hawke’s Bay earthquake struck in 1931 two men were working in the base of the 95-metre-high Mōhaka viaduct. Stuck in a small compartment 18 metres under the riverbed, they were subject to violent rocking, and water rose to shoulder height. The terrified men were winched out by a third man working immediately above. The first to emerge, desperate to escape, lunged for a compressed air valve. The quick-thinking winchman knocked him unconscious, preventing the death from the bends of all three.
New Zealand is located in the Pacific-rim earthquake zone, and like Japan and California developed sophisticated earthquake engineering techniques. Engineering schools at Auckland and Canterbury universities have undertaken full-scale testing and evaluation of structural elements. Base-isolation techniques, which allow buildings to move during earthquakes, were developed by New Zealand engineers and scientists.
Engineering in wartime
The Second World War pushed New Zealand engineering in a military direction. Small shipbuilding work included local assembly of British-designed Fairmile launches for anti-submarine work. Munitions were also assembled.
Yacht design and building
Mechanical engineer Jack Brooke designed more than 250 yachts, and built many himself. From the 1920s, he produced novel – and, at the time, controversial – designs that won national championships.
Brooke went on to design New Zealand’s Spirit of Adventure, and the Ji Fung for Outward Bound in Hong Kong. Brooke was an early exponent of a yacht design and building industry that flourished in West Auckland in the 20th century.
Urban engineering continued as New Zealand’s towns and cities expanded. In Auckland the Grafton bridge was built in 1910 – a 97.6 metre ferroconcrete structure linking Grafton Road with Symonds Street in the city. Steel-reinforced ferroconcrete was a relatively new material that made it possible to construct the tall buildings that began to appear in New Zealand’s major centres in this period.