The art of tunnelling was first developed by miners. Those who came to the Otago goldfields excavated tunnels up to 150 metres long. Overseas, railway tunnels had been built soon after trains were introduced. The first rail tunnel in the United States was built in 1833, and in the United Kingdom a tunnel on the Sheffield–Manchester line opened in 1845.
A fair day’s pay?
Tunnelling was always hard, poorly-paid work, but the pay did increase dramatically over time. In 2009 dollars, those working on the Lyttelton tunnel in 1861 were paid 14 cents an hour; Public Works Department tunnellers in 1953 received 70 cents an hour, and were loaned protective clothing. Those working on the Kaimai tunnel earned $3.28 an hour, plus safety footwear and two pairs of overalls; those tunnelling the Rangipō tailrace made $4.21 an hour, with allowances for wet time and underground work.
When Provincial Superintendent William Moorhouse proposed a rail tunnel to link the growing town of Christchurch with its port at Lyttelton in October 1858, it was a bold move. The recommendation for a tunnel had come from George Robert Stephenson, nephew of the rail pioneer George Stephenson. The tunnel was the first in the world to be driven through an extinct volcano, and the alleged hardness of the rock was the main reason that the initial contractors, John Smith and George Knight of Westminster, withdrew from the project. The Melbourne firm of George Holmes & Co. accepted the contract for £240,000 for the whole 9.6-kilometre line from Christchurch to Lyttelton – of which the 2.6-kilometre tunnel was worth £195,000.
The first sod was turned on 17 July 1861. The project was fraught with difficulties – many early workers downed tools and left for the Otago gold rushes, floods of water had to be siphoned out, and smoke from gunpowder was a problem until a flue was set up in the top part of the tunnel. But in May 1867 the tunnel broke through, and in December it was formally opened. There were two deaths among the workers, who laboured in poor conditions using picks and shovels.
As railway building proceeded from the 1870s, many smaller tunnels were constructed, such as those on the line to Hawke’s Bay through the Manawatū Gorge, and on the North Island main trunk line. The Midland railway from Christchurch to the West Coast had 17 tunnels when completed in 1923. The most remarkable was the 8,529-metre Ōtira tunnel through the Southern Alps. A contract was originally let to John McLean and sons in 1907 for almost £600,000; but after five years of technical difficulties and labour conflicts the work was only half done, so the firm petitioned to be relieved of the contract. It was taken over by the Public Works Department and the last stick of dynamite was fired in August 1918. The line finally opened in 1923. At the time the tunnel was the longest outside the Alps, where there were six longer tunnels.
Since 1878 the Wellington rail link to the Wairarapa over the Remutaka Range had involved a Fell engine, which gripped a centre rail on the steep sections of the line. It was slow, and greatly limited the quantity of freight. In 1948 it was agreed to build a tunnel. The project was undertaken by a joint venture between the United States firm Morrison Knudsen and the local firm Downer & Co. The Americans introduced full-face excavation to New Zealand – until then all tunnels had been built using the heading and bench system, where a heading shaft was excavated and then the rest dug out below. The new method increased the speed, especially since the tunnellers worked 24 hours a day, six days a week. In one particular week the tunnellers advanced 76 metres, a world record for building a tunnel with support. The tunnel, at 8,798 metres slightly longer than the Ōtira, was opened in 1955, just over two years after digging began. However the work cost three lives – two from falls and one from a premature explosion.
In her valedictory speech in 2009, former Prime Minister Helen Clark recalled that on her first campaign in 1975 she was unable to accompany the minister of transport, Basil Arthur, into the Kaimai tunnel because of the superstition that women were bad luck in an unfinished tunnel.
New Zealand’s most recent major rail tunnel, the country’s longest at 8,879 metres, was through the Kaimai Range. It opened in 1978, eight years later than planned. The tunnel was designed to dramatically shorten the route from Waikato to the Bay of Plenty and from Auckland to Tauranga. It was also intended to overcome the problems with the old east-coast line, which was steep, had sharp curves, and was often blocked by slips. Work began in 1965, and about half of the tunnelling was carried out by a tunnel boring machine. On 24 February 1970 four workers were killed when the roof caved in. Seven others were successfully rescued.