Purewa Tunnel is a rail tunnel in

Auckland Auckland (pronounced ) ( mi, Tāmaki Makaurau) is a large metropolitan city in the North Island of New Zealand. The List of New Zealand urban areas by population, most populous urban area in the country and the List of cities in Oceania by po ...

, New Zealand. It is on the

North Island Main Trunk The North Island Main Trunk (NIMT) is the main railway line in the North Island of New Zealand, connecting the capital city Wellington with the country's largest city, Auckland. The line is long, built to the New Zealand rail gauge of and ser ...

line and is located in the suburb of Saint Johns, to the west of Glen Innes. The tunnel is concrete-lined. Eastern Line passenger services operate through it, and it is also used by the

Northern Explorer The ''Northern Explorer'' is a long-distance passenger train operated by The Great Journeys of New Zealand division of KiwiRail between Auckland and Wellington in the North Island of New Zealand, along the North Island Main Trunk (NIMT). Three ...

and freight services.

Background

Proposals were made as early as the 1870s to re-route the Auckland–Westfield section of the North Island Main Trunk via a new eastern route through Glen Innes. Referred to as the Westfield Deviation, this was an easier grade than the NIMT's relatively steep uphill grade from central Auckland to Newmarket and

Remuera Remuera is an affluent inner city suburb of Auckland, New Zealand. It is located four kilometres southeast of the city centre. Remuera is characterised by many large houses, often Edwardian or mid 20th century. A prime example of a "leafy" sub ...

. By the 1920s, increasing traffic and delays between Auckland and Newmarket made the new route necessary.

Construction

The tunnel was started in March 1925 by workers experienced in the 'hard school... fthe notorious railway tunnels of North Auckland' (i.e. constructing the

North Auckland Line The North Auckland Line (designation NAL) is a major section of New Zealand's national rail network, and is made up of the following parts: the portion of track that runs northward from Westfield Junction to Newmarket Station; from there, wes ...

). With the assistance of horse-driven carts, the mining workers, mostly British (with some Italians and Dalmatians in the groups preparing the approach cuttings), were reported to have made good progress, working in triple shifts, using

gelignite Gelignite (), also known as blasting gelatin or simply "jelly", is an explosive material consisting of collodion-cotton (a type of nitrocellulose or guncotton) dissolved in either nitroglycerine or nitroglycol and mixed with wood pulp and saltpe ...

emplaced in drill holes to fracture the rock. The tunnel, while lit by electric lights during the excavation, was described as hosting a large number of

glowworm Glowworm or glow-worm is the common name for various groups of insect larvae and adult larviform females that glow through bioluminescence. They include the European common glow-worm and other members of the Lampyridae, but bioluminescence also o ...

s, giving it a 'weird and fantastical' appeal. Miners reported that the worms, likely to have entered from the nearby bush-clad gullies, were unlike anything they had ever reported in a working tunnel. Further, the tunnel was also strangely attractive to a large number of sparrows that came to populate it, living from pilfered horse feed and becoming quite inured to the regular explosions. Break through was in April 1926 and the tunnel was completed in March 1928. The Westfield Deviation, including the tunnel, opened for goods traffic on 1 September 1929, using the ''down'' line to

Westfield Junction Westfield Junction is a railway switching junction on the Auckland railway network in New Zealand. It is north of Otahuhu station and is surrounded by the industrial area of Westfield. Westfield Junction defines the southernmost extremity ...

for single-line working, but was not used for passenger traffic until the ''up'' line to Auckland was opened on 11 May 1930.

Later work

The tunnel has in the past experienced some significant water drainage issues, which have required remedial work, and the installation of speed restrictions. In 2010/2011, tracks within the tunnel were lowered to allow the required clearance for the

Auckland railway electrification Auckland railway electrification occurred in phases as part of investment in a new infrastructure for Auckland's urban railway network. Electrification of the network had been proposed for several decades. Installation started in the late 2000s a ...

project.

External links

Photo of western approach construction - Auckland Weekly News 7 May 1925
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2014 You Tube video of diesel trains

References

{{Coord, 36, 52, 16.61, S, 174, 50, 54.4, E, display=title Railway tunnels in New Zealand Rail transport in Auckland Tunnels completed in 1929 Transport buildings and structures in the Auckland Region