New Zealand Railways Bridges & Tunnels

(Produced by Publicity and Advertising Branch, New Zealand Railways, 1967)

(revised 2004 by Garvan Laing)


Bridges and Viaducts

New Zealand is a country of rivers and streams, some deep and swift, others wide and slow-moving, but subject to heavy flooding when the alpine snows melt in spring. To carry the railway tracks over the deep gorges and the wide rivers, the engineers have had to build more than 2,500 bridges and viaducts with an aggregate length of 89 km. The longest bridges are in the South Island and the highest viaducts are in the North Island.

The longest railway bridge in New Zealand is that over the Rakaia River, 55
km. south of Christchurch. It is 1743 m long and comprises 143×12.2 m steel plate-girder spans supported on concrete piles. Completed in December 1939, it replaced an even longer timber structure used as a combined road and railway bridge since the 1870s.

Other long bridges include the Waitaki, between Timaru and Oamaru, and the Waiau, in North Canterbury. Both in the South Island, they are 914 m and 700 m long respectively. In the North Island, the longest structure is the Tauranga Harbour Bridge. Completed in 1924, it comprises 14×32 m through-type steel truss spans, 448 m in all.

Twenty-three New Zealand railway viaducts carry the rails more than 100 feet (30.5m) above the streams they cross, and eight of these are more than 200 feet (61 m) high. It is noteworthy also that five of the latter are located between Napier and Gisborne.

The highest viaduct is the Mohaka, a towering steel structure carrying the Napier-Gisborne railway 97 m above the bed of the Mohaka River. Next highest is the Makatote Viaduct, a short distance South of National Park.


New Zealand Railway Viaducts

Name Height (m) Length (m) Location
Mohaka 97 277 34 km south of Wairoa
Makatote 79 262 11 km S. of National Park
Waikare 78 187 Just N. of Putorino
South Rangitikei 75 315 Between Mangaweka and Utiku
Makohine 73 137 11 km S. of Mangaweka
Waikoau 72 160 45 km N. of Napier
Staircase 72 146 W. of Springfield (Sth. Is.)
Maungaturanga 66 244 24 km S. of Wairoa
Matahoura 66 141 6 km S. of Putorino
Toi Toi 58 66 11 km S. of Taihape
Broken River 56 134 W. of Springfield (Sth. Is.)
Hapuawhenua 45 284 3 km N. of Ohakune
Wingatui 45 198 Otago Central Line, 13 km N-W. of Wingatui
Slovens Creek 41 166 W. of Springfield (Sth. Is.)
Mangarangiora 40 259 Just N. of Ormondville
Kopuawhara 40 162 50 km N. of Wairoa
Poolburn Gorge (Note) 37 108 Otago Central line, between Ida Valley and Omakau
Paterson Creek
37 187 W. of Springfield (Sth. Is.)
Manawapou 37 148 16 km N. of Patea
Waiteti 36 129 3 km N. of Te Kuiti
Manganui-o-te-Ao 34 75 13 km S. of National Park
Taonui 34 122 6 km N. of Ohakune
Price's Creek (Note) 32 91 Otago Central line, 33 km N. of Middlemarch


Note: No longer in railway use - line closed, tracks lifted. Now a horse and
cycle-trekking route.


The longest single spans used in New Zealand railways viaducts are in the Waikoau and Matahoura Viaducts, on the Napier-Gisborne railway. Each of these structures includes a 76 m steel span weighing 335 tonne. Another notable viaduct on this line is the Kopuawhara, which is a graceful reinforced concrete structure incorporating a spandrel arch giving a clear span of 55 metres.

Many new railway bridges have been built in New Zealand in recent years in line with the Railways Department's policy of progressively replacement of outdated structures. A notable feature is the increasing adoption of reinforced concrete for the construction of spans as well as piers. Among several all-concrete railway bridges brought into use since 1960 are the 549 m Ashley bridge opened in Canterbury in 1961, the 914 m Waitaki bridge, and the 143 m bridge over the Waikato River at Hamilton, both opened in 1964, and the 133 m Waitohi Viaduct near Picton opened in November 1965.



The hilly and mountainous nature of much of New Zealand has necessitated the driving of numerous railway tunnels in order that distances and gradients could be kept within acceptable limits. At the end of March 1967, a total of 189 tunnels with an aggregate length of 86 km were in use, 108 in the North Island and 81 in the South Island. This represents one tunnel for each 27 km of railway track.

Six of these tunnels are more than a mile in length. They are the Rimutaka (8.79 km), completed in 1955 between Upper Hutt and Featherston on the Wairarapa line; Otira (8.57 km) on the Midland line in the South Island, opened in 1923; Tawa No.2 (4.33 km) near Wellington, first used in 1935; Tikiwhata (1.86 km) between Wairoa and Gisborne, opened in 1942; Lyttleton (2.60 km), the oldest, brought into use in 1867; Turakina (2.09 km) between Marton and Wanganui, opened in 1947. The Rimutaka, Tawa, and Turakina tunnels are located on railway deviations constructed to replace older railways which had steep gradients and sharp curves that made them unsuitable for economic operation in modern conditions.

If the two Simplon tunnels side by side between Switzerland and Italy be regarded as one tunnel, the Rimutaka Tunnel is the twelfth longest in the world, and the Otira Tunnel is the fifteenth longest. The new Kaimai Tunnel is the longest railway tunnel in the Commonwealth and in the southern hemisphere.

The North Island main trunk line passes through 26 tunnels between Wellington and Auckland. Among the names of these tunnels are Mole, Rabbit, Hedgehog, Beaver, Possum, Elk, Moose, and Neptune. One of the two tunnels on the Raurimu Spiral actually passes beneath another curve of the track above it.

On the South Island Midland line between Avoca and Kowai Bush, where the railway winds through the Waimakariri Gorge in the foothills of the Southern Alps, there are 16 tunnels in 13 km. On the South Island main trunk line, where the railway skirts the sea beneath the Kaikoura Mountains, tunnels have been built over the line to protect the track from falls of rock or
shingle. One of these is the only railway tunnel in New Zealand provided with windows, which are located on the seaward side.

In 1964, preparations were begun for the boring of yet another long railway tunnel in New Zealand. This is approximately 8.85 km long through the Kaimai Hills between Hamilton and Tauranga on a new line that will shorten the distance between these two cities from 151 km to 100 km.

(Produced by Publicity and Advertising Branch, New Zealand Railways, 1967)

Since the original article was written, the 8,850-metre Kaimai tunnel came into use. Also, the Mangaweka viaduct was demolished and that section of the line, passing, as it does, through unstable country, has been replaced by a deviation which includes the all-concrete South Rangitikei Viaduct (315 metres long by 75 metres high) and two other shorter bridges; also by-passed are six tunnels: Kowhai, Moose, Elk, Deer, Possum and Black.

All measurements are converted from the original miles, chains and feet to metric units, to the nearest significant figure.
-- Garvan Laing.

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