View source for NZR Tunnels

== INTRODUCTION ==
Tunnels and railways are to many people synonymous in that the early railway design philosophy in England called for near-level railways to reduce the load on the engines, but invariably led to the need for tunnels. In contrast, they then also introduced the 'inclined plane', it being the other extreme, where by railway wagons were hauled up steep grades by rope in order to reach a different 'level' of railway. These too were often through tunnels.

New Zealand being a very young country when railways were first introduced, had to tackle the issue of mountains from the very start. The options were to go round them or through them, and the engineers of the day usually took the middle ground, bu climbing up as far as practical and then piercing the ridge with a tunnel. The tunnel to Lyttelton, completed in 1863 was built very much along traditional English designs but the options of creating a shorter tunnel by climbing higher were extremely constrained due to the location of the port. Its construction proved what could be done on the other side of the world.

The Dunedin and Port Chalmers Railway (1872) was much more conservative in its approach to obstacles it could not climb over or go round. Two short tunnels met their needs but one of those has since been replaced by a much longer tunnel on a much better alignment. That is typical of much of New Zealand, the need for a tunnel will often result in a difficult track alignment up to the  the tunnel making significant improvements to the alignment very expensive. North of Dunedin the mainline climbs over a significant hill with virtually continuous curves for some 15km. Along the way there were four tunnels the longest one 1.3km is currently the most restrictive tunnels on the KiwiRail network having been constructed in 1874. Several times investigations have looked at alternative routes, but even with halving the track distance and  eliminating all the steep grades, it was not economic as it required a new 7 - 8km long tunnel. Similar cases would exist throughout the country with an emphasis on eliminating tunnels wherever possible due to their loading gauge constraints and challenging work environments. Recent legislation (following the Pyke River coal mine disaster) has required KiwiRail to adopt work-practices designed for mines, when working in tunnels greatly increasing the cost of all types of tunnel work.

From a peak of 130 tunnels, KiwiRail still has 100 tunnels on its network, though a significant number are on mothballed lines. The following tables give a summary of all tunnels constructed on railway lines operated by the Government railways at some point in its life. This is an interim way of presenting this dataprior to getting it all working through the Cargo database. The tables are arranged with the Line name as part of the page headings so individual Lines can be accessed more easily. They can be selected from the 'Table of Contents' at the top of the page.

Most tunnels received names, many just their location, but a good number had far more creative names, with their true origins long lost as time has gone by. There is plenty of scope to debate these origins in the discussion pages associated with each tunnels home page.

The data for the tunnel tables is currently being collated and will be added here progressively from 11/06/2024

== NORTH ISLAND ==

=== North Island Main Trunk ===

Construction of the [[North Island Main Trunk]] line was commenced from either end long before it could be envisaged that a continuous route linking Wellington and Auckland was even possible. Because of this, non of the tunnels were built for the line they are now on. In simple terms, Wellington to Palmerston North was built by the Wellington and Manawatu Railway Company, Palmerston North to Marton was constructed as part of the line to New Plymouth Line , Marton to Ohakune was constructed for the NIMT but known as the Marton Branch until the track was linked up north of Ohakune. From the North, Auckland to Penrose was built as part of the line to Onehunga, Penrose to Te Kuiti was built as the Waikato Line and Te Kuiti to Ohakune was built for the NIMT but operated as the Auckland Section Until the line was completed. At that point in time, The line from Auckland to Wellington was operated as a complete route from Auckland, however the mileage from Auckland only ran as far as Marton, and the mileage from Wellington went all the way to New Plymouth.  In 1974, when New Zealand adopted the metric system of weights and measures, all lines were remeasured and the opportunity was taken to make the NIMT a complete line in its own right with its start at Wellington (0km) and end at Auckland  (681km). From that quick summary, you can see that reference to a tunnel can be quite confusing and using names will have been a convenient way of avoiding confusion. Because the km posts (the [[linear referencing]] system) start at Wellington, the data table will be presented in that order with a separate column to note the original Line name. For completeness, and as an aid to cross referencing with old documents, the original Line names will all get their own tables as well. In this way the first 12 tunnels will also be listed on the [[Wellington and Manawatu Railway]] table. Tunnel numbers in brackets indicates that tunnel is no longer used, refer to the comments column for details.

{| class="wikitable"
|+  Tunnels on the [[North Island Main Trunk]]
! Line Name
! Tunnel No
! Original Line Name
! Original No
! Opened
! Tunnel Name
! Station Prior
! Station After
! Length
|-
| [[North Island Main Trunk]]
|(1)
| [[Wellington and Manawatu Railway]]
|1
|1885
| [[Outlet Tunnel|Outlet]]
| [[Thorndon]]
| [[Ngaio]]
|126
|Transferred to [[Johnsonville Line]] 1937
|-
| [[North Island Main Trunk]]
|(2)
| [[Wellington and Manawatu Railway]]
|2
|1885
| [[Kaiwarra Tunnel|Kaiwarra]]
| [[Thorndon]]
| [[Ngaio]]
|98
|Transferred to [[Johnsonville Line]] 1937
|-
| [[North Island Main Trunk]]
|(3)
| [[Wellington and Manawatu Railway]]
|3
|1885
| [[Gorge Tunnel|Gorge]]
| [[Thorndon]]
| [[Ngaio]]
|151
|Transferred to [[Johnsonville Line]] 1937
|-
| [[North Island Main Trunk]]
|(4)
| [[Wellington and Manawatu Railway]]
|4
|1885
| [[Lizard Tunnel|Lizard]]
| [[Thorndon]]
| [[Ngaio]]
|199
|Transferred to [[Johnsonville Line]] 1937
|-
| [[North Island Main Trunk]]
|(5)
| [[Wellington and Manawatu Railway]]
|5
|1885
| [[Ngaio Tunnel|Ngaio]]
| [[Thorndon]]
| [[Ngaio]]
|127
|Transferred to [[Johnsonville Line]] 1937
|-
| [[North Island Main Trunk]]
|(6)
| [[Wellington and Manawatu Railway]]
|6
|1885
| [[Kaka Tunnel|Kaka]]
| [[Khandallah]]
| [[Raroa]]
|104
|Transferred to [[Johnsonville Line]] 1937
|-
| [[North Island Main Trunk]]
|(7)
| [[Wellington and Manawatu Railway]]
|7
|1885
| [[Tui Tunnel|Tui]]
| [[Raroa]]
| [[Johnsonville]]
|119
|Transferred to [[Johnsonville Line]] 1937
|-
| [[North Island Main Trunk]]
|1
|
|
|1937
| [[Tawa No 1  Tunnel|Tawa No 1 ]]
| [[Kaiwharawhara]]
| [[Takapu Road]]
|1238
|Double track opened 1937
|-
| [[North Island Main Trunk]]
|2
|
|
|1937
| [[Tawa No 2 Tunnel|Tawa No 2]]
| [[Kaiwharawhara]]
| [[Takapu Road]]
|4325
|Double track opened 1937
|-
| [[North Island Main Trunk]]
|3
| [[Wellington and Manawatu Railway]]
|8
|1886
| [[Pukerua Tunnel|Pukerua]]
| [[Pukerua Bay]]
| [[Paekakariki]]
|153
|
|-
| [[North Island Main Trunk]]
|4
| [[Wellington and Manawatu Railway]]
|9
|1886
| [[St Kilda Tunnel|St Kilda]]
| [[Pukerua Bay]]
| [[Paekakariki]]
|290
|
|-
| [[North Island Main Trunk]]
|5
| [[Wellington and Manawatu Railway]]
|10
|1886
| [[Seaview Tunnel|Seaview]]
| [[Pukerua Bay]]
| [[Paekakariki]]
|187
|
|-
| [[North Island Main Trunk]]
|6
| [[Wellington and Manawatu Railway]]
|11
|1886
| [[Brighton Tunnel|Brighton]]
| [[Pukerua Bay]]
| [[Paekakariki]]
|244
|
|-
|
|
| [[Wellington and Manawatu Railway]]
|12
|1886
| [[Tunnel 12 Tunnel|Tunnel 12]]
| [[Pukerua Bay]]
| [[Paekakariki]]
|271
|bypassed in 1900 due to instability
|-
| [[North Island Main Trunk]]
|7
| [[Wellington and Manawatu Railway]]
|13
|1886
| [[Neptune Tunnel|Neptune]]
| [[Pukerua Bay]]
| [[Paekakariki]]
|59
|
|-
| [[North Island Main Trunk]]
|(8)
| [[Main Trunk Line]]
|20
|1893
| [[Moa Tunnel|Moa]]
| [[Kaikarangi]]
| [[Mangaonoho]]
|83
|bypassed  as part of 4km deviation in 1985
|-
|
|
| [[Main Trunk Line]]
|19
|1893
| [[Kiwi Tunnel|Kiwi]]
| [[Kaikarangi]]
| [[Mangaonoho]]
|76
|daylighted 1972, site bypassed 1985
|-
| [[North Island Main Trunk]]
|(9)
| [[Main Trunk Line]]
|18
|1902
| [[Makohine Tunnel|Makohine]]
| [[Mangaonoho]]
| [[Ohingaiti]]
|180
|daylighted 1984
|-
| [[North Island Main Trunk]]
|10
| [[Main Trunk Line]]
|17
|1902
| [[Powhakaroa Tunnel|Powhakaroa]]
| [[Ohingaiti]]
| [[Mangaweka]]
|549
|
|-
| [[North Island Main Trunk]]
|(10a)
| [[Main Trunk Line]]
|16
|1904
| [[Kowhai Tunnel|Kowhai]]
| [[Mangaweka]]
| [[Utiku]]
|111
|bypassed 1981
|-
| [[North Island Main Trunk]]
|(10b)
| [[Main Trunk Line]]
|15
|1904
| [[Moose Tunnel|Moose]]
| [[Mangaweka]]
| [[Utiku]]
|77
|bypassed 1981
|-
| [[North Island Main Trunk]]
|(10c)
| [[Main Trunk Line]]
|14
|1904
| [[Elk Tunnel|Elk]]
| [[Mangaweka]]
| [[Utiku]]
|174
|bypassed 1981
|-
| [[North Island Main Trunk]]
|(10d)
| [[Main Trunk Line]]
|13
|1904
| [[Deer Tunnel|Deer]]
| [[Mangaweka]]
| [[Utiku]]
|214
|bypassed 1981
|-
| [[North Island Main Trunk]]
|(10e)
| [[Main Trunk Line]]
|12
|1904
| [[Possum Tunnel|Possum]]
| [[Mangaweka]]
| [[Utiku]]
|542
|bypassed 1981
|-
| [[North Island Main Trunk]]
|(10f)
| [[Main Trunk Line]]
|11
|1904
| [[Black Tunnel|Black]]
| [[Mangaweka]]
| [[Utiku]]
|423
|bypassed 1981
|-
| [[North Island Main Trunk]]
|(11)
| [[Main Trunk Line]]
|10
|1904
| [[Beaver Tunnel|Beaver]]
| [[Utiku]]
| [[Taihape]]
|420
|bypassed 1985
|-
| [[North Island Main Trunk]]
|(12)
| [[Main Trunk Line]]
|9
|1907
| [[Hedgehog Tunnel|Hedgehog]]
| [[Taihape]]
| [[Mataroa]]
|115
|bypassed 1985
|-
| [[North Island Main Trunk]]
|13
| [[Main Trunk Line]]
|8
|1907
| [[Pit Tunnel|Pit]]
| [[Taihape]]
| [[Mataroa]]
|609
|
|-
| [[North Island Main Trunk]]
|14
| [[Main Trunk Line]]
|7
|1908
| [[Rabbit Tunnel|Rabbit]]
| [[Ngaurukehu]]
| [[Turangariri]]
|113
|
|-
| [[North Island Main Trunk]]
|(15)
| [[Main Trunk Line]]
|6
|1908
| [[Mole Tunnel|Mole]]
| [[Ohakune]]
| [[Horopito]]
|208
|bypassed 1987
|-
| [[North Island Main Trunk]]
|16
| [[Main Trunk Line]]
|5
|1908
| [[Upper Spiral Tunnel|Upper Spiral]]
| [[National Park]]
| [[Raurimu]]
|384
|
|-
| [[North Island Main Trunk]]
|17
| [[Main Trunk Line]]
|4
|1908
| [[Lower Spiral Tunnel|Lower Spiral]]
| [[National Park]]
| [[Raurimu]]
|95
|
|-
| [[North Island Main Trunk]]
|(18)
| [[Main Trunk Line]]
|3
|1908
| [[Porootarao Tunnel|Porootarao]]
| [[Porootarau]]
| [[Waimiha]]
|1071
|replaced by new tunnel 1980
|-
| [[North Island Main Trunk]]
|18
| [[Main Trunk Line]]
|2
|1980
| [[Porootarao Tunnel|Porootarao]]
| [[Porootarau]]
| [[Waimiha]]
|1272
|
|-
| [[North Island Main Trunk]]
|(2)
| [[Waikato Railway]]
|2
|1875
| [[Mercer Tunnel|Mercer]]
| [[Mercer]]
| [[Whangamarino]]
|30
|daylighted 1956
|-
| [[North Island Main Trunk]]
|(1)
| [[Onehunga Railway]]
|1
|1873
| [[Parnell Tunnel|Parnell]]
| [[Auckland]]
| [[New Market]]
|336
|Replaced with new tunnel 1909
|-
| [[North Island Main Trunk]]
|(1)
|
|1
|1915
| [[Parnell Tunnel|Parnell]]
| [[Auckland]]
| [[New Market]]
|343
|Double track. To [[Newmarket Branch]] 1930
|-
| [[North Island Main Trunk]]
|19
| [[Westfield Deviation]]
|1
|1930
| [[Purewa Tunnel|Purewa]]
| [[Glenn Innes]]
| [[Purewa]]
|596
|Double track opened Nov 1930
|}

=== North Auckland Line ===


== SOUTH ISLAND ==

=== Main South Line ===

The Main South Line was the first line to link main centres in New Zealand by 1878 it linked Christchurch with Dunedin and Invercargill, a total distance of nearly 600km. There was also the Lyttelton Line linking Christchurch with its port at Lyttelton and this was incorporated in the Main South Line very early on. The line passes through extremely varied county with long stretches of very easy going, to a number of very difficult sections, particularly around Dunedin. A total of 11 tunnels were required, one to access the port at lyttelyon, the longest tunnel in the British empire at the time, one just south of Oamaru, and the other 9 all close to Dunedin. Three of those  were replaced by double track tunnels early in the 20th century, one was bypassed due to unstable ground, and one short one was daylighted rather than enlarged to accommodate shipping containers. The remaining four all had extensive work carried out to enable container traffic to pass on standard wagons. Mihiwaka tunnel, the longest of those was constructed in 1874 and is now the narrowest tunnel still in use by KiwiRail. The following table lists all the Main South Line tunnels with their important details.

{| class="wikitable"
|+  Tunnels on the [[Main South Line]]
! Line Name
! Tunnel No
! Original Line Name
! Original No
! Opened
! Tunnel Name
! Prior Station
! Next Station
! Length
|-
| [[Main South Line]]
|1
| [[Canterbury Railways]]
|1
|1867
| [[Lyttelton Tunnel|Lyttelton]]
| [[Lyttelton]]
| [[Heathcote]]
|2595
|Built for broad gauge (1600mm)
|-
| [[Main South Line]]
|2
|
|2
|1876
| [[Otepopo Tunnel|Otepopo]]
| [[Herbert]]
| [[Waianakarua]]
|262
|
|-
| [[Main South Line]]
|(3)
|
|3
|1878
| [[Puketeraki Tunnel|Puketeraki]]
| [[Puketeraki]]
| [[Seacliff]]
|157
|bypassed 1936 due to instability
|-
| [[Main South Line]]
|4
|
|4
|1891
| [[Cliffs Tunnel|Cliffs]]
| [[Waitati]]
| [[Osbourne]]
|277
|built to bypass unstable cliff
|-
| [[Main South Line]]
|5
|
|5
|1877
| [[Mihiwaka Tunnel|Mihiwaka]]
| [[Mihiwaka]]
| [[Upper Port Chalmers]]
|1408
|floor lowered 1970-71
|-
| [[Main South Line]]
|(6)
|
|6
|1877
| [[McGregor Tunnel|McGregor]]
| [[Mihiwaka]]
| [[Upper Port Chalmers]]
|68
|daylighted 1971
|-
| [[Main South Line]]
|7
|
|7
|1877
| [[Mansford Tunnel|Mansford]]
| [[Mihiwaka]]
| [[Upper Port Chalmers]]
|187
|floor lowered 1970
|-
| [[Main South Line]]
|(8)
| [[Dunedin & Port Chalmers Railway]]
|1
|1872
| [[Roseneath Tunnel|Roseneath]]
| [[Sawyers Bay]]
| [[Burkes]]
|101
|bypassed 1948
|-
| [[Main South Line]]
|8
|
|8
|1948
| [[Blanket Bay Tunnel|Blanket Bay]]
| [[Sawyers Bay]]
| [[Burkes]]
|303
|double track
|-
| [[Main South Line]]
|(9)
| [[Clutha Railway]]
|1
|1874
| [[Caversham  Tunnel|Caversham ]]
| [[Caversham]]
| [[Burnside]]
|865
|bypassed 1910
|-
| [[Main South Line]]
|9
|
|9
|1910
| [[Caversham  Tunnel|Caversham ]]
| [[Caversham]]
| [[Burnside]]
|1407
|double track, single tracked c1988
|-
| [[Main South Line]]
|(10)
| [[Clutha Railway]]
|2
|1875
| [[Chain Hills  Tunnel|Chain Hills ]]
| [[Abbotsford]]
| [[Wingatui]]
|453
|bypassed 1914
|-
| [[Main South Line]]
|10
|
|10
|1914
| [[Chain Hills  Tunnel|Chain Hills ]]
| [[Abbotsford]]
| [[Wingatui]]
|889
|double track, single tracked c1988
|}