New Zealand has a long history of electric-powered railways. Before the 1980s they were confined to Wellington’s commuter lines and two South Island tunnels. Our first electric railway opened in 1923. This was a 14km section running through the long Otira tunnel on the transalpine line between Christchurch and Greymouth.
In 1929 electric locomotives were introduced on the Christchurch–Lyttelton line, which included the Lyttelton tunnel. Electric propulsion was seen as ideal for use in tunnels, to avoid the smoke nuisance caused by steam locomotives. Both of these sections were subsequently converted to diesel haulage – the Lyttelton line in 1970 and Otira in 1997.
In 1938, following the completion of the Tawa Flat deviation out of Wellington, the old Johnsonville route (originally built by the Wellington and Manawatu Railway Company in the 1880s) was converted into an electrified suburban line, served by English Electric multiple units. By 1940 the North Island Main Trunk (NIMT) out of Wellington had been electrified as far north as Paekakariki (extended to Paraparaumu in the 1980s). In the early 1950s electric multiple units were introduced on the busy Hutt Valley suburban lines.
Large scale electrificationNew Zealand’s biggest rail electrification project – involving the NIMT between Hamilton and Palmerston North – was undertaken in the 1980s. The electrification of the whole NIMT had been proposed in 1950, in response to post-war coal shortages, but the government instead opted for diesel propulsion. The idea was revived during the oil shocks of the 1970s, and electrification of the central section was approved in 1980.
This project involved the erection of more than 10,000 concrete poles, while a number of tunnels had to be ‘daylighted’ or have their floors lowered to accommodate overhead wires. Electrification was completed in 1988, at a final cost of around $250 million. Unlike the Wellington suburban lines, which use a 1.5kV DC system, the NIMT uses 25kV AC.
In 2007 the government announced another major electrification project, with work on the Auckland suburban network due to be completed by 2013.