NZR Tunnels

INTRODUCTION

Tunnels and railways are to many people synonymous, in that the early railway design principles in England called for near-level railways to reduce the load on the engines, which 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 railway on a different 'level'. 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, by climbing up as far as reasonable grades could take them, and then piercing the ridge with as short a tunnel as possible. The tunnel to Lyttelton (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 by determined immigrants 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 Two short tunnels met their needs but one of those has since been replaced by a much longer tunnel on a much better alignment.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 tunnels imposing severe restrictions on the loading gauge, there is now a focus on eliminating tunnels wherever possible. Tunnels also create an extremely challenging work environment, particularly since recent legislation (following the Pyke River coal mine disaster) has required KiwiRail to adopt work-practices designed for mines, whenever work in tunnels is planned, greatly increasing the cost of any work done in tunnel.

From a peak of 130 tunnels, KiwiRail still has about 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 data prior 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.

Tunnels on the North Island Main Trunk Past and Present

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

SOUTH ISLAND

Main North Line

The Main North Line was the last of the main lines to be completed and this did not happen until 1945. With the subsequent introduction of the rail ferries between Wellington and Picton, it enabled all New Zealand railways (except for the soon to close Nelson Section) to be truly called a network.

Tunnels on the Main North Line Past and Present

Line Name	Tunnel No	Original Line Name	Original No	Opened	Tunnel Name	Prior Station	Next Station	Length
Main North Line	1	South Island Main Trunk		1945	No1	Claverley	Oaro	76
Main North Line	2	South Island Main Trunk		1945	No2	Claverley	Oaro	51
Main North Line	3	South Island Main Trunk		1945	Amuri Bluff	Claverley	Oaro	975
Main North Line	(4)	South Island Main Trunk		1945	No4	Claverley	Oaro	188	bypassed due to unstable ground 1956?
Main North Line	5	South Island Main Trunk		1945	No5	Oaro	Goose Bay	208
Main North Line	6	South Island Main Trunk		1945	No6	Goose Bay	Puketa	126
Main North Line	7	South Island Main Trunk		1945	Raramai	Goose Bay	Puketa	114
Main North Line	8	South Island Main Trunk		1945	No8	Goose Bay	Puketa	154
Main North Line	9	South Island Main Trunk		1945	No9	Goose Bay	Puketa	253
Main North Line	10	South Island Main Trunk		1945	No10	Goose Bay	Puketa	100
Main North Line	11	South Island Main Trunk		1945	Kowhai	Goose Bay	Puketa	393
Main North Line	12	South Island Main Trunk		1945	Paratitahi	Goose Bay	Puketa	897
Main North Line	13	South Island Main Trunk		1945	No13	Goose Bay	Puketa	116
Main North Line	14	South Island Main Trunk		1945	Rileys Hill (Kahutara)	Goose Bay	Puketa	452
Main North Line	15	South Island Main Trunk		1944	No15	Maungamanu	Rakautara	217
Main North Line	16	South Island Main Trunk		1944	No16	Maungamanu	Rakautara	123
Main North Line	17	South Island Main Trunk		1944	No17	Maungamanu	Rakautara	187
Main North Line	18	South Island Main Trunk		1944	Shands	Rakautara	Pines	209
Main North Line	19	South Island Main Trunk		1944	No19	Rakautara	Pines	642
Main North Line	20	South Island Main Trunk		1944	No20	Rakautara	Pines	130
Main North Line	21			2021	No 21	Wharanui	Mirza	100	Road Overpass
Main North Line	(21)	Picton Section	3	1911	Tar Barrel	Wharanui	Mirza	164	Bypassed 2021
Main North Line	(22)	Picton Section	2	1902	No22	Dashwood	Vernon	70	Daylighted 1981
Main North Line	(23)	Picton Section	1	1902	No23	Dashwood	Vernon	50	Daylighted 1979
Main North Line	(24)			1950	No24	Tuamarina	Para	48	Road Overpass

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 lyttelton, 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.

Tunnels on the Main South Line Past and Present

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	Lyttelton	Heathcote	2595	Built for broad gauge (1600mm)
Main South Line	2	Waitaki - Moeraki Railway	1	1876	Otepopo	Herbert	Waianakarua	262
Main South Line	(3)		3	1878	Puketeraki	Puketeraki	Seacliff	157	bypassed 1936 due to unstable hill
Main South Line	4			1891	Cliffs	Waitati	Osbourne	277	built to bypass unstable cliff
Main South Line	5		4	1877	Mihiwaka	Mihiwaka	Port Chalmers Upper	1408	floor lowered 1970-71
Main South Line	(6)		5	1877	Macgregor	Mihiwaka	Port Chalmers Upper	68	daylighted 1971
Main South Line	7		6	1877	Mansford	Mihiwaka	Port Chalmers Upper	187	floor lowered 1970
Main South Line	(8)	Dunedin & Port Chalmers Railway	1	1872	Roseneath	Sawyers Bay	Burkes	101	bypassed 1948
Main South Line	8			1948	Blanket Bay	Sawyers Bay	Burkes	303	double track
Main South Line	(9)	Clutha Railway	1	1874	Caversham	Caversham	Burnside	865	bypassed 1910
Main South Line	9			1910	Caversham	Caversham	Burnside	1407	double track, single tracked c1988
Main South Line	(10)	Clutha Railway	2	1875	Chain Hills	Abbotsford	Wingatui	453	bypassed 1914
Main South Line	10		10	1914	Chain Hills	Abbotsford	Wingatui	889	double track, single tracked c1988