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Bridges and tunnels

by Jock Phillips

New Zealand’s hilly terrain and many rivers made bridges and tunnels a necessity, and their opening was often celebrated by large crowds. Notable bridges include the kilometre-long Auckland Harbour Bridge, and the impressive series of elegant railway viaducts on the North Island main trunk line.


The need for bridges and tunnels

In 2009 New Zealand had 2,174 rail bridges and over 15,600 road bridges. There were 150 rail tunnels, totalling more than 87 kilometres in length. From 2000 to 2008 an average of over $9.7 million was spent annually on new road bridges.

Mountains and rivers

The high number of bridges and tunnels is due to New Zealand’s difficult terrain. Travelling inland involves crossing mountain ranges and gorges. The high rainfall and steep hill country create many rivers, which become wide and braided on the plains. The difficulty in crossing these rivers led to drowning being known as the ‘New Zealand death’ in the 19th century.

Changing types of transport

Māori and early Pākehā settlers largely travelled on foot, or by canoe up rivers, so they needed no more than occasional footbridges. To cross wide, deep rivers they used canoes or punts. Once people began travelling in coaches and transporting goods in carts, bridges became necessary. Many early bridges were only just the width of a cart. When the internal combustion engine arrived and two-lane highways were built, there was a need for more and wider bridges, although one-lane bridges remained common in rural areas.

The development of railways was a major reason for building bridges and tunnels. It was harder for trains to climb hills than it was for horses or automobiles, so railways needed tunnels.

New Zealand’s first significant tunnel was the rail tunnel between Lyttelton and Christchurch, built in the 1860s. When the Otago Central Railway was built through the Taieri Gorge in the 1880s, 16 new bridges were needed. When the Midland rail line was completed between Canterbury and the West Coast in 1923, it included 17 tunnels, five bridges and five viaducts. A number of bridges carried both road and rail; in 2009 three remained in use, out of 42 or more originally designed for both forms of transport. There were three double-storeyed bridges with the road underneath and the rail on top – at Seddon in Marlborough, at Ōkahukura near Ōngarue, and at Karangahake on the Paeroa–Waihī line.

The tunnel between Lyttelton port and Christchurch was built because large ships could not make it over the Sumner bar to reach the city. Elsewhere the need to keep rivers open for boats led to swing bridges, such as on the Heathcote River in Christchurch, while Auckland Harbour Bridge had to be high enough to let ships underneath.

Watery tunnel

New Zealand’s first tunnel is said to have been constructed in 1846 by James Crawford, who built a tunnel to drain water from his farm at Burnham Water, Wellington, into Evans Bay.

Other reasons

Bridges were constructed as cities grew. Christchurch was built on both sides of the Avon River, and Hamilton developed both east and west of the Waikato River. Before the Auckland Harbour Bridge was constructed, cars could only reach the North Shore on vehicular ferries, or by a long drive. Wellington was hilly and tunnels were built.

Gold miners built bridges to carry water races. Loggers often constructed rail tracks for bush trams to carry logs; on occasion these called for viaducts. The most spectacular examples were the four viaducts on the Port Craig bush line in Southland, including the Percy Burn viaduct, which was 125 metres long and 36 metres high. Power and sewerage schemes often required the construction of long tunnels.


Building bridges and tunnels

New Zealand conditions made building bridges and tunnels major engineering feats. Many were in isolated areas, where bringing in supplies was difficult. The heavy rainfall led to floods, which regularly washed away early bridges, and the humidity made wooden bridges rot. Wind could also be a problem. For tunnel builders there was a constant battle against water, and the unstable terrain and frequent earthquakes made the rock hard to work.

Wise old dog

The Waiau River bridge was awarded a prize at the 1865 Dunedin exhibition, but it was said that during a strong nor-wester a shepherd’s dog refused to cross. The dog obviously knew something because in a fierce north-west gale in November 1874 the bridge collapsed.

Overseas and local contractors

Overseas contractors were brought in for large projects such as the Lyttelton tunnel and the Auckland Harbour Bridge. Parts such as iron balustrades for bridges were often imported.

Increasingly, work was done by local companies. The tender for the bridges on the Otago Central Railway in the 1890s required the iron girders to be made in New Zealand. From the late 1870s the Christchurch firm of J. and A. Anderson’s had extensive work building bridges. In 1887 alone, Anderson’s was involved in constructing the Beaumont bridge over the Clutha, the Waiau Ferry bridge in North Canterbury, two bridges on the North Island main trunk railway, a suspension bridge over the Hope River, and eight bridges on the Taieri Gorge line. Usually they built temporary workshops close to the sites.

On some major projects, like the Remutaka rail tunnel in the early 1950s, a local firm, Downer and Co., combined with an overseas company (in this case American) to do the work.

Role of government

At first responsibility for organising bridges and tunnels lay with local communities, but from 1852 provincial governments were responsible and provincial engineers did the planning. In 1870 the Public Works Department (PWD) was set up. It appraised projects and supervised contracts. After the provinces were abolished in 1876 the PWD took on responsibility for their public works. Local projects became the responsibility of county councils, which often received loans or subsidies from the PWD.

At first the department did none of the construction, but in the 1890s they began to contract groups of workers to build smaller bridges. The Makōhine viaduct on the North Island main trunk railway line in 1902 was the first major project using contracted workers. In 1912 the department took over building the Ōtira tunnel through the Southern Alps after the private contractor, John McLean, withdrew.

The Main Highways Act 1922 set up the Main Highways Board, which took responsibility for the major highways (about one-seventh of all formed roads). The board funded many concrete bridges as road transport took off in the interwar years – in 1935, for example, it provided funds for 250 bridges. The board also initiated the Homer Tunnel, on the way to Milford Sound, in the late 1930s. From 1989 the state highway network’s roads, bridges and tunnels were managed by a new Crown entity, Transit New Zealand. In 2008 Transit merged with Land Transport New Zealand to become the NZ Transport Agency.

In the 2000s local authorities remained responsible for bridges on local roads, including many one-lane bridges in rural areas.

Party poopers

When work began on the Lyttelton tunnel in July 1861, 1,500 people assembled at the northern portal to celebrate. But the wet weather and poor-quality beer did not please the crowd, which attacked the marquee and tore it to shreds.

Celebrations

Bridges and tunnels required a large investment, they often took a long time to complete, and they usually promised exciting opportunities for local growth. So their progress was followed closely.

Most openings were happy, crowded community celebrations. Usually a dignitary such as a minister, or even the premier, would cut the ribbon. In 1896 the small Manawatū settlement of Āpiti celebrated the completion of a bridge over the Ōroua River which opened a direct route to Feilding. Four hundred people turned out to hear Premier Richard Seddon, followed by a banquet and music from the local brass band. The bridge over the Taieri River at Hyde was opened in 1879 by the engineer’s wife breaking a bottle of champagne against the bridge. The obligatory banquet followed.

Flat champagne?

When the Waiau River ferry bridge opened in 1887, replacing the ferry, there was a grand opening, with a huge marquee erected on the flat land near the bridge. It has been known ever since as ‘Champagne Flat’.

Bridge memorials

Bridges were sometimes seen as appropriate sites for memorials. At least three bridges recalled the dead of the First World War. The 1899 Clifden suspension bridge in Southland had memorial plaques added later; at Kaiparoro in northern Wairarapa a sturdy concrete bridge recalls the local dead; and in Christchurch the ostentatious Bridge of Remembrance was built at the spot where thousands of soldiers marched across the Avon en route from King Edward’s barracks to the railway station.

The Edith Cavell bridge on the Shotover River received its name when a local miner, miffed that his suggestion had been spurned, painted the name on the bridge and it stuck. In Central Otago, the bridge at Ophir was named after Irish patriot Daniel O’Connell, probably in recognition of Irish gold miners.


Types of bridges

Early bridges

The earliest bridges in New Zealand were simply the trunks of trees laid across a stream. Many Māori paths crossed such bridges.

British settlers brought a long tradition of bridge-building, especially arched stone bridges and, later, iron bridges. The first constructed in New Zealand was a humpback bridge over the Waitangi River in 1830.

Beam bridges

The simplest type of bridge was the girder or beam bridge, which stretched from one side of a river to the other. Where the river was too wide, the beams rested on supporting piers in midstream. This style of bridge was common in New Zealand because it was normally the cheapest. It was used for the long bridges crossing the wide braided rivers of Canterbury.

Truss bridges

Where builders found it difficult to extend a beam bridge by erecting supporting piers, beams could be made stronger and longer by using a truss. This was a triangle where the two side struts in effect held up the bottom beam. Sometimes the deck was at the base of the triangles; sometimes it ran along the top. Truss bridges developed in North America, where there was abundant wood, and they were relatively common in 19th-century New Zealand because of the availability of wood. The first was built over the Hutt River at Petone in 1847. Wooden truss bridges had a narrow carriageway, and as native timber often rotted, few remained in the 2000s.

Suspension bridges

Suspension bridges are most common as ‘swing bridges’ on tramping (hiking) tracks. The bridge is suspended from two metal cables, and can span a considerable distance. Cheap to build, they were quite common in the 19th century. The first was probably the Waiwakaiho River bridge, built in New Plymouth in 1842. It was suspended from the anchor chains from the Fifeshire, which had been wrecked earlier that year in Nelson.

Bungy bridges

The Kawarau suspension bridge was the site of New Zealand’s first bungy operation – with a 43-metre leap – in 1988. The Kawarau bridge was built in 1880 from a design and specifications drawn up by the engineer Harry Higginson in a remarkable 16 days. Another bungy bridge is the 1901 Skippers bridge near Queenstown, the highest suspension bridge in the country at 91.4 metres.

Arch bridges

Stone arch bridges were less common in New Zealand than in Britain because of the relative lack of building stone. As well as some stone bridges, a few timber and iron arch bridges were built. Hamilton’s Victoria Road bridge over the Waikato River (1908) was a steel arch. There were more concrete arch bridges. Most arched bridges had the deck on top of the arch, but sometimes the arch was above the deck – a ‘bowstring arch’. The Ōpawa River bridge at Blenheim and the Balclutha bridge over the Clutha River/Mata-Au are good examples of bowstring-arch bridges.

Materials

Wood

Wood, being cheap and plentiful, was at first the main material used to build bridges. Tōtara was common in the 19th century, but it tended to rot, so later Australian hardwoods were imported and used. Wooden bridges were still built in the 1930s in rural areas and often painted in red oxide. By the 1950s many had rotted, and temporary bailey bridges were used until concrete replacements were built.

Musical bridges

Even when bridges were not built wholly of wood, the decking was often wooden. The planks on the bridge over the Hokitika River became loose and the structure became known as ‘the longest xylophone in the world’.1

Stone

Because of a lack of both masons and suitable stone, few stone bridges were built in New Zealand. The exceptions were in South Canterbury where there were 28 masonry bridges, most built in the 1870s and 1880s, and in North Otago where limestone was used for the Waianakārua River bridge, the oldest on State Highway 1. There were brick bridges in Christchurch and Akaroa.

Iron

Wrought-iron balustrades were first used in the 1860s. The first significant use of iron girders was on a road–rail bridge over the Waitaki River in 1876. Iron girders became common in the first half of the 20th century. Iron trusses were also used, notably on the Rangitātā River bridge near Arundel in 1872.

Concrete

Concrete was excellent for beam bridges and arches. The first reinforced concrete bridge was built over the Leith in Dunedin in 1903. In 1910 the Grafton bridge in Auckland became the world’s largest reinforced concrete arch bridge; 21 years later the Kelburn viaduct was built in Wellington. Taranaki was especially forward-looking in using concrete arched bridges. In 1954 another major development occurred when the Hutt estuary bridge used post-tensioned pre-stressed concrete. Pre-stressed concrete made possible slim and elegant constructions like the 1987 Hāpuawhenua viaduct on the North Island main trunk railway line.

Footnotes
  1. Geoffrey Thornton, Bridging the gap: early bridges in New Zealand 1830–1939. Auckland: Reed, 2001, p. 104. Back

Notable bridges

Clutha bridges

At 322 kilometres, the Clutha River/Mata-Au is New Zealand’s second-longest river. Running from Lake Wānaka to the sea, it traverses areas settled during the 1860s Otago gold rushes. Bridging the Clutha was a considerable challenge, which became clear in the great flood of 1878. The Bannockburn bridge on the Kawarau River was swept away, and its wreckage destroyed the Clyde bridge on the Clutha, which in turn ruined the Roxburgh bridge, a laminated wooden arch, only erected in 1875. Further downstream the Beaumont bridge was washed away and it in turn destroyed the Balclutha bridge.

The flood began a period of bridge-building:

  • Balclutha, 1881 – a wooden truss bridge to replace the lost one, but it did not last either. A concrete bridge with bowstring arches opened in 1935.
  • Alexandra, 1882 – a handsome suspension bridge resting on two schist masonry towers.
  • Roxburgh, 1887 – a new suspension bridge, and a truss bridge at Beaumont, the first iron bridge made in the colony.
  • Millers Flat, 1899 – a steel bowstring arch
  • Horseshoe Bend, 1913 – a handsome swing footbridge.

In 2009 a river punt remained at Tuapeka Mouth. It had operated since 1896, but in the 2000s most cars used the Clydevale bridge, 10 kilometres downstream.

Bridal bridge

The Millers Flat bridge was due to be opened by Premier Richard Seddon in January 1899. He had another engagement and asked for the opening to be delayed. But a couple had arranged to be married on that day so they could be the first to drive over the new bridge. Flags flew, bands played, beer was poured and the newlyweds drove across. Then the bridge was padlocked to await the premier a month later. In his speech Seddon won no friends by attacking the locals for their unofficial opening.

Christchurch

Christchurch has long been known as a city of bridges because the Avon River flows through its centre. In the 2000s there were 26 road bridges and seven footbridges on its 22-kilometre length. In the 1850s wooden bridges were built for carts or pedestrians – but most rotted. The first to be made of permanent materials was the Victoria Street bridge, built of stone and imported cast iron in 1864.

New, wider bridges were erected in the next decade – five in 1875 alone. Most were wood – though some had handsome iron balustrades. Many lasted until the 1950s, when six new concrete-slab bridges were opened, followed in the 1960s by 13 road bridges and three footbridges, mostly of pre-stressed concrete.

Main trunk line viaducts

In most western countries, a viaduct is a structure with many arches and small spans. In New Zealand the term usually applies to high railway structures – probably because of the remarkable series of viaducts which cross the steep ravined country in the middle sections of the North Island main trunk railway line, completed in 1908. Of more than 20 viaducts on the line, nine were substantial, including:

  • the Makōhine viaduct (1902), just south of Ōhingaiti – 228 metres long and 73 metres high
  • the Mangaweka viaduct (1903) – 288 metres long and 47 metres high, and originally the longest on the line, it was bypassed and demolished in 1981
  • the Makatote viaduct (1908), 12 kilometres south of National Park – 78.6 metres high, it was the highest on the line at the time it was built
  • the Hāpuawhenua viaduct (1908) – 284 metres long, it was the second-longest at the time it was built.

Died in the course of duty

The major main trunk viaducts were designed by Peter Hay, an engineer in the Public Works Department. But he did not see the fruits of his work – the year before the main trunk opened he suffered from exposure while inspecting the line, developed pleurisy and died.

In 1981 the Mangaweka deviation was built. It included the north Rangitīkei and south Rangitīkei and Kawhatu viaducts, all made of pre-stressed concrete. At 81 metres the northern viaduct became the highest on the line. Six years later the Ohakune to Horopito deviation involved a new Hāpuawhenua viaduct. It was 414 metres long – the country’s longest rail viaduct.

Auckland Harbour Bridge

The most spectacular bridge in New Zealand is the Auckland Harbour Bridge, built between 1955 and 1959. The need for better transport between Auckland city and the North Shore had long been the subject of inquiry and agitation. Finally the Auckland Harbour Bridge Authority was set up in 1950 to raise funds and organise construction. The bridge’s ‘coat hanger’ design, with lattice girders above the road on the 243-metre span between the first and second pier, allows ships to pass beneath.

Building the bridge involved clever cantilevering of the steel girders, and staff working 33 metres below sea level preparing the foundations of the reinforced concrete piers. The bridge is 1,017 metres long, and used 5,670 tonnes of steel, 17,160 cubic metres of concrete and 6,800 litres of paint.

The ‘pick-a-back’ span

When constructing the Auckland Harbour Bridge, the span between the second and third piers was constructed on top of the span between the fifth and sixth piers. The two spans were floated into position together, the top one was fixed to its piers and the bottom span moved back to its original position. The ‘pick-a-back’ span weighed 1,000 tonnes and was 176 metres long.

Originally the bridge was four lanes, but this quickly proved inadequate. In 1969 the ‘Nippon clip-ons’ – two lanes on each side, pre-fabricated in Japan – were added. At the time this was pioneering technology, but 15 years later fatigue was discovered in the weld of the splice joints and several thousand joints had to be replaced. Tolls were charged on the bridge until 1984.


Rail tunnels

Origins

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.

 

Lyttelton tunnel

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.

Ōtira tunnel

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 British Empire’s longest and the world’s sixth-longest.

Remutaka tunnel

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.

Men only

 

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.

 

Kaimai 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.


Road and utility tunnels

Because cars are better at climbing hills than trains are, New Zealand has fewer road tunnels. Some are very short, such as several on the coast road near Kaikōura – and some are significant, despite being short. Wellington’s hilly topography has made road tunnels especially important. The Mt Victoria tunnel (1931) linked the city’s airport and eastern suburbs with the city; the Karori, Seatoun and Northland tunnels had already helped open up those suburbs. The Terrace tunnel (1978) brought the northern motorway into the city centre.

Beep, beep

 

Wellington’s Mt Victoria tunnel is known for drivers tooting their horns as they pass through, almost deafening the few hardy pedestrians. Some suggest that the tooting began as a tribute to Phyllis Simmons, who was buried alive in the spoil from the project by a tunnel labourer, George Coates. Coates was hanged at Mt Crawford prison in 1931.

 

Longest tunnels

New Zealand’s two longest road tunnels are the Homer Tunnel and the Lyttelton tunnel.

The Homer Tunnel was first suggested in 1890 as a route to Milford Sound. Work on it finally began in 1935 as an unemployment relief project with little more than shovels and wheelbarrows. With heavy rain and snow, and tent accommodation, the working conditions were awful, and three workers were killed by avalanches. Hole-through came in 1940, but it was not until 1954 that the first car used the tunnel, which is 1,255 metres long.

Miles of tiles

 

The Lyttelton road tunnel is lined with 1.25 million tiles. If all the tiles were placed end to end they would stretch 185 kilometres.

 

In 1961, 100 years after the first sod was turned for the Lyttelton–Christchurch rail tunnel, work began on a road tunnel to link the city and port. As with the Auckland Harbour Bridge, an authority was set up to take responsibility for the construction – and as with the Remutaka tunnel, the tender went to a combination of an American firm, Kaiser Engineers, and a local firm, Fletcher Construction. The tunnel, 1,900 metres long, opened in 1964. Tolls were charged until 1978.

Other tunnels

Tunnels have also been constructed in New Zealand for hydro-electricity schemes, city infrastructure, and defence.

  • Manapōuri power scheme: between 1964 and 1968 a 9.8-kilometre tunnel was built between the west arm of Lake Manapōuri and Doubtful Sound to provide a tailrace for the Manapōuri power scheme. Sixteen men died during the construction. A second tunnel was completed in 2002.
  • Tongariro power scheme: during the 1970s, 10 tunnels were excavated as part of this scheme, which involved taking water from the south-east and western side of Mt Ruapehu to the Rangipō and Tokaanu power stations north of the mountain. The Moawhango tunnel, 19.2 kilometres long, was one of the longest hydro tunnels in the world, and the longest ever constructed from only two entrances, one at each end.
  • Auckland city infrastructure: a 9.4-kilometre tunnel was completed in 2000 for new 110-kV cables from the Penrose substation into central Auckland. In 2009 a 3-kilometre sewerage tunnel was being built under Hobson Bay in Auckland.
  • Defence purposes: in 1942, as anxiety about Japanese air raids intensified, air-raid shelters were constructed under Albert Park in Auckland. At the same time gun emplacements involving extensive tunnels were built at Stony Batter on Waiheke Island, and on Wright’s Hill in Wellington.

External links and sources

More suggestions and sources


How to cite this page: Jock Phillips, 'Bridges and tunnels', Te Ara - the Encyclopedia of New Zealand, http://www.TeAra.govt.nz/en/bridges-and-tunnels/print (accessed 6 August 2020)

Story by Jock Phillips, published 11 Mar 2010