North Island Main Trunk

North Island Main Trunk
	Map of the North Island Main Trunk
Overview
Type	Heavy rail
System	New Zealand railway network
Status	Open
Locale	North Island, New Zealand
Termini	Wellington; Auckland Britomart Transport Centre
Operation
Opened	14 August 1908 (railheads meet) ; 6 November 1908 (official opening) ; 14 February 1909 (line completed)
Owner	KiwiRail
Operator(s)	KiwiRail (freight) ; KiwiRail Scenic Journeys (long-distance passenger) ; Transdev Wellington (Wellington–Waikanae) ; Transdev Auckland (Pukekohe–Auckland)
Character	Main line
Rolling stock	EF class electric locomotives (Te Rapa - Palmerston North)
Technical
Line length	681 km (423 mi)
Number of tracks	Triple track Wellington–Wairarapa Line junction; double track Wairarapa Line junction–Pukerua Bay, Paekakariki–Waikanae, Hamilton–Te Kauwhata, Amokura–Auckland; remainder single track
Track gauge	1,067 mm (3 ft 6 in)
Electrification	1600 V DC overhead Wellington–Waikanae; 25 kV 50 Hz AC overhead Palmerston North–Te Rapa, Papakura–Britomart
Operating speed	110 km/h (68 mph) maximum
Highest elevation	832 metres (2,730 ft)
Route map
	Legend
	The Strand Station
	formerly Auckland railway station
	Mission Bush Branch &
	Glenbrook Vintage Railway
	Whangaehu River
	site of Tangiwai disaster
	This diagram: view; talk; edit;

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 682 kilometres (424 mi) long and passes through Paraparaumu, Palmerston North, Taihape, National Park, Taumarunui, Te Kuiti, Hamilton, and Pukekohe.

Most of the NIMT is single track with frequent passing loops, built to the New Zealand rail gauge of 1,067 mm (3 ft 6 in). The line is double track between Wellington and Waikanae (apart from an 8.7 km (5.4 mi) single track section between Pukerua Bay and Paekakariki), between Hamilton and Te Kauwhata (except for the single track Waikato River Bridge at Ngaruawahia), and between Meremere and Auckland Britomart. Around 460 kilometres (290 mi) (approximately 65%) of the line is electrified in three separate sections: one section at 1600 V DC between Wellington and Waikanae, and two sections at 25 kV AC: 412 km (256 mi) between Palmerston North and Te Rapa (Hamilton) and 34 km (21 mi) between Papakura and Auckland Britomart.

The first section of what became the NIMT opened in 1873 in Auckland. Construction at the Wellington end began in 1885; the line was completed in 1908 and was fully operational by 1909. It is credited for having been an economic lifeline for the young nation, and for having opened up the centre of the North Island to European settlement and investment.^[1] In the early days, a passenger journey between Wellington and Auckland could take more than 20 hours; today, the Northern Explorer takes approximately 11 hours.^[2]

The NIMT has been described as an "engineering miracle",^[3] with numerous engineering feats such as viaducts, tunnels and a spiral built to overcome large elevation differences with grades suitable for steam engines.

History[edit]

Construction[edit]

Auckland to Te Awamutu[edit]

Auckland's first railway was the 13 km (8.1 mi) line between Point Britomart and Onehunga via Penrose, opened in 1873 (see photo of first train). It was built by Brogdens;^[4] the section from Penrose to Onehunga is now called the Onehunga Branch. The line was later continued south from Penrose into the Waikato, possibly to support the Invasion of the Waikato, a 3.5 mi (5.6 km) tramway being built from Maungatawhiri to Meremere in 1864,^[5] though turning of the first sod of the Auckland and Drury Railway took place in 1865, a year after the last major battle.^[6] This line reached Mercer by 20 May 1875, with 29 km (18 mi) from Ngaruawahia being constructed by the Volunteer Engineer Militia and opened on 13 August 1877, it was extended to Frankton by December 1877, and to Te Awamutu in 1880. An economic downturn stalled construction for the next five years, and Te Awamutu remained the railhead. There were also protracted negotiations with local Māori, and the King Country was not accessible to Europeans until 1883.

Wellington to Marton[edit]

The Wellington-Longburn (near Palmerston North) section was constructed between 1881 and 1886 by the Wellington and Manawatu Railway Company (WMR); the company was acquired by the New Zealand Railways Department in 1908.

Central North Island[edit]

From Te Awamutu it was proposed that the line be built via Taupo or via Taumarunui, the eventual route. Four options were considered before the Minister of Public Works decided on the present route in 1884, but, when it was realised just how difficult that route was, further surveys considered two other options in 1888.^[7] Construction of the final central section began on 15 April 1885, when paramount chief Wahanui of Ngāti Maniapoto turned the first sod outside Te Awamutu, it was 23 years before the two lines met, as the central section was difficult to survey and construct. The crossing of the North Island Volcanic Plateau with deep ravines required nine viaducts and the world-famous Raurimu Spiral. By the beginning of 1908, there was a 39 km (24 mi) gap between Erua and Ohakune, with a connecting horse-drawn coach service. From Ohakune south to Waiouru the Public Works Department operated the train, as this section had not yet been handed over to the Railways Department.

Opening[edit]

The gap was closed on 7 August 1908 for the first through passenger train, the 11-car Parliamentary Special carrying the Prime Minister Sir Joseph Ward and other parliamentarians north to see the American Great White Fleet at Auckland,^[1] but much of the new section was temporary, with some cuttings north of Taonui having vertical batters and some unballasted sections of track. Ward drove the last spike on 6 November 1908, and the 'Last Spike' monument is at Manganui-o-te-Ao 39°16.44′S 175°23.37′E / 39.27400°S 175.38950°E / -39.27400; 175.38950, near Pokaka. A two-day NIMT service started on 9 November, with an overnight stop at Ohakune.

On 14 February 1909 the first NIMT express left Auckland for Wellington, an overnight trip scheduled to take 19 hours 15 minutes, with a sleeping car, day cars with reclining seats, and postal/parcels vans; the dining car went on the north express from Wellington to Ohakune, then transferred to the southbound express, so avoiding the heavy gradients of the central section.

Track upgrades[edit]

Several sections of the line have been upgraded and deviated:

In 1913 the maximum speed limit on the NIMT was raised to 45 mph (72 km/h), reducing the journey time by 1 hour 25 minutes Auckland-Wellington or to 17 hours and between 30 and 45 minutes.^[8] Under T. Ronayne, the Railways Department general manager from 1895 to 1913,^[9] the section south to Parnell was duplicated and improvements made to the worst gradients and tight curves between Auckland and Mercer. Under his successor E. H. Hiley the second Parnell Tunnel with two tracks and an easier gradient was completed in 1915-1916. On the Kakariki bank between Halcombe and Marton a deviation reduced the 1 in 53 grade to 1 in 70.^[10] A 1914 Act authorised spending on the Westfield Deviation, new stations at Auckland and Wellington, track doubling (Penrose-Papakura, Ohinewai-Huntly, Horotiu-Frankton, Newmarket-New Lynn), and grade easements from Penrose to Te Kuiti,^[11] but the war delayed most of these works for over a decade.

In 1927 automatic colour-light signalling was installed from Otahuhu to Mercer.^[12] In 1930 the signalling was extended 34 mi 72 ch (56.2 km) to Frankton and the 6 mi 55 ch (10.8 km) from there to Horotiu was doubled. The 3 mi 54 ch (5.9 km) north to Ngāruawāhia was doubled from 5 Dec 1937,^[13] followed by 9 mi 12 ch (14.7 km) Ngāruawāhia to Huntly on 4 Dec 1938^[14] and Huntly to Ohinewai and Papakura to Paerata in December, 1939.^[15] By then, wartime shortages delayed further double-tracking.^[16] Pokeno to Mercer was doubled from 11 Nov 1951, Pukekohe to Pokeno 21 Nov 1954, Mercer to Amokura 1 Jul 1956 and Ohinewai to Te Kauwhata 14 Dec 1958; the 13 km (8.1 mi) between Amokura and Te Kauwhata remain single track, as does Ngāruawāhia bridge.^[17]

Approaching Auckland CBD through the eastern suburbs on the Westfield deviation to the North Island Main Trunk.

In 1930 the Westfield Deviation was opened, creating a new eastern route from Auckland to Westfield via Glen Innes and Hobsons Bay, running into the new Auckland railway station and providing better access to the Port of Auckland; the original section between Auckland and Westfield via Newmarket later ceased to be part of the NIMT: Auckland to Newmarket became the Auckland-Newmarket Line, and Newmarket to Westfield became part of the North Auckland Line (NAL) which runs between Whangarei and Westfield.

In the late 1930s, bridges replaced level crossings at Ohinewai, Taupiri and Hopuhopu.^[18]

In the 1930s, the Wellington end was deviated from Wellington to Tawa Flat by the Tawa Flat deviation, including two long tunnels. The deviation is the centre two tracks, with the Wairarapa Line's Ngauranga station in the background, alongside State Highway 1.

The double track Tawa Flat deviation opened to goods trains on 22 July 1935 and to passenger trains on 19 June 1937, bypassing the original single track WMR line between Wellington and Tawa. With a pair of tunnels under the Wellington hills, the deviation alleviated issues with more and heavier freight traffic on the steep twisting original route; the Wellington to Johnsonville section of the original line was retained as the Johnsonville Line and the Johnsonville to Tawa section closed.

Planned in conjunction with the Tawa Flat deviation, electrification at 1500 V DC of the southern section of the NIMT from Wellington to Paekakariki was completed on 24 July 1940, eliminating the need to relieve the steep (1 in 57) gradients to the Pukerua Bay summit by a deviation to the east and the smoke problem in the new long Tawa No. 2 tunnel. The electrification allowed suburban electric multiple units to run on this section from September 1949.

EW1805 hauling DC 4611 near Paekakariki on the electrified Wellington section. This section of the North Island Main Trunk was electrified in 1940.

Following the Tawa Flat deviation, work continued on duplication of the line from Wellington to Paekakariki to provide for more frequent suburban passenger trains; the sections from Plimmerton to South Junction, north of Pukerua Bay, and North Junction to Paekakariki were completed in 1940. The difficult section with tunnels between South and North Junctions remains single track. Duplication from Tawa to Porirua opened on 15 December 1957, from Porirua to Paremata on 7 November 1960, and Paremata to Plimmerton on 16 October 1961.The section between Porirua and Plimmerton was straightened in conjunction with the duplication by reclaiming land along the eastern shore of Porirua Harbour.

Between 1964 and 1966 a deviation away from the centre of Palmerston North via the Milson deviation on the edge of the city.

In 1967 the floors of the tunnels on the WMR section between Paekakariki and Pukerua Bay were lowered to enable the DA class locomotives to travel all the way to Wellington.

Between 1973 and 1981 the major Mangaweka deviation in the central section between Mangaweka and Utiku was built, with three viaducts, all over 70m tall, crossing the Rangitikei and Kawhatau rivers.

The central section from Te Rapa near Hamilton to Palmerston North was electrified at 25 kV AC between 1984 and 1988 as part of the Think Big government energy programme; some tunnels were opened out or bypassed by deviations while in others clearances were increased, and curves eased. The section between Ohakune and Horopito was realigned with three viaducts replaced to handle higher loads and speeds; the most notable bridge replaced was the curved metal viaduct at Hapuawhenua by a modern concrete structure, though the original has been restored as a tourist attraction.

In 2009–10, the 1.5 km section of line between Wellington Junction and Distant Junction was rebuilt from double track to triple track, to ease peak-time congestion.

In February 2011 duplication between Paekakariki and Waikanae was completed as part of the upgrade and expansion of the Wellington suburban network; see Kapiti Line for more information.

In 2012-13 four bridges near Rangiriri between Auckland and Hamilton were replaced; the bridges were all over 100 years old with steel spans and timber piers, and were replaced by modern low-maintenance concrete ballast deck bridges. Bridges 479, 480, 481 & 482 were replaced, with lengths of 40 metres (131 ft 3 in), 40 metres (131 ft 3 in), 30 metres (98 ft 5 in) and 18 metres (59 ft 1 in) respectively.^[19]

The construction of the Peka Peka to Otaki section of the Kapiti Expressway required 1.3 km of the NIMT immediately north of Otaki station to be realigned. Construction began in 2017, and trains were switched onto the new alignment over the 2019 Easter long weekend (19–22 April).^[20]^[21]

A DL class locomotive hauling a freight train at Papakura, south of Auckland. Freight is an important revenue earner for the North Island Main Trunk.

In the Auckland area, a third main line between Wiri and Westfield^[22] or Wiri and Papakura, to allow freight trains to bypass stationary passenger trains, has been proposed.^[23]

Electrification[edit]

There are three independent sections of the NIMT which are electrified: Auckland's urban network (25 kV AC), Wellington's urban network (1600 V DC), and the central section (25 kV AC) from Palmerston North - Te Rapa (north of Hamilton).

Electrification of the NIMT was mooted by electrical engineer Evan Parry in the first volume of the New Zealand Journal of Science and Technology in November 1918. In light of a national coal shortage following World War I, Parry argued that the network was under great strain due to ever-increasing volumes of freight, and the use of steam traction was partly to blame. Parry also noted that there was great potential for cheap hydro-electricity generation in the central North Island to power electrification.

The first part of the NIMT to be electrified was the Wellington–Paekakariki section via the Tawa Flat deviation that was completed on 24 July 1940; this was largely to prevent smoke nuisance in the 4.3 km No. 2 tunnel, and to provide for banking on the Paekakariki to Pukerua Bay section. Electric traction in this section is now used only by Transdev Wellington for Metlink suburban passenger services on the Kapiti Line, and was extended to Paraparaumu on 7 May 1983 and Waikanae on 20 February 2011. Funded by the Greater Wellington Regional Council, the extension to Waikanae coincided with the delivery of new FP class Matangi electric multiple units.^[24]

Following the Second World War railway services suffered due to skill and coal shortages. Skilled staff sought employment opportunities elsewhere in the economy. From 1948 to 1951 the General Manager of the Railways Department, Frederick Aickin, advocated electrification of the entire line, despite protests from his engineering staff. Aickin had previously been Staff Superintendent and Chief Legal Advisor to the Department, and considered using diesel locomotives for trains on the NIMT to be too expensive, he turned his attention to electrification, mainly because he saw that it could relieve the coal situation and prevent high expenditure on imported fuels.

He commissioned a study into electrification, which concluded that a low-frequency AC system could be cheaper than 1500 V DC, the system in use in Wellington. Aicken sent a technical mission of four senior officers overseas in March 1949 and travelled overseas himself to negotiate a tentative contract with a British construction company; the Chief Mechanical Engineer and Chief Accountant specified and costed the system and Aicken was able to complete a substantial report justifying the NIMT electrification and submit it to the Government.

Officers from New Zealand Treasury and the Ministry of Works and two experts from Sweden (Thelander and Edenius) commented on the proposal and in December 1950 the Government granted approval in principle and agreed to appoint Thelander as a consultant. However, Aickin fell out with the then National Government and retired as General Manager in July 1951. With the change in regime, the electrification proposal disappeared.

A key assumption of Aickin's report was that traffic on the NIMT would grow by 50% from 1948 to 1961. Since a diesel-electric locomotive was in fact a travelling power station, the savings through electrification compared to diesel could be regarded as the difference between the cost of buying bulk electrical energy generated substantially from New Zealand resources and the cost of generating electricity in a small plant using imported diesel fuel.

However, the Royal Commission on Railways created following Aickin's tenure rejected the report's findings. Aickin's successor, H.C. Lusty, revised the tentative contract with English Electric to specify DF diesel-electric locomotives, they were later found to be unreliable, and only ten were supplied. 42 DG locomotives were supplied instead for secondary lines. For main lines including the NIMT, D^A class diesel-electric locomotives were ordered from General Motors.

The 411 km (255 mi) section between Palmerston North and Hamilton was electrified at 25 kV 50 Hz AC, opened in June 1988 as one of the Muldoon National Government's "Think Big" energy development projects. An overall cost in excess of $100 million had been projected, with some 40% being for the locomotives, but the final cost was about $250 million; the economics of the project was greatly undermined by the fall of the price of oil in the 1980s and the deregulation of land transport, which removed the long-distance monopoly NZR held when the cost-benefit report was written.

EF30163 hauling The Overlander on the 25 kV AC electrified section in 2003.

The electrification of the section, which had its genesis in a study group set up in June 1974 to report on measures to be taken to cope with increasing rail traffic volumes, received approval in 1980; this led to a technical study carried out with assistance from the Japanese Railway Technical Research Institute. The report stated that track capacity would be increased by electrification because such traction is faster and able to move more freight at once; the report stated, for example, that whereas a diesel locomotive could haul 720-tonne trains at 27 km/h (17 mph) up the Raurimu Spiral, an electric locomotive could haul 1100/1200-tonne trains at 45 km/h (28 mph), cutting 3–5 hours off journey times. Less fuel would be needed and employing regenerative braking in electric locomotives lowers the fuel consumption further.

Electrification's advantages were reflected in the economic evaluation in the report, which showed a rate of return of 18%. Sensitivity analysis showed that this high rate of return gave the project robustness against lower traffic volumes than expected (the return remained positive even if traffic fell), against significant increases in construction cost, and against lower than expected rises in the diesel fuel price.

Part of the project included replacing the copper wire communications system with a new fibre optic communications cable (due to interference caused by AC power with the DC copper wire system) between Wellington and Auckland. In 1994 New Zealand Rail Limited sold the cable to Clear Communications for telephone traffic, leasing part of it back for signalling.^[25]

Proposals to electrify the Auckland suburban rail network dated back to the 1960s,^[26] they mainly coincided with proposals to electrify the NIMT in its entirety. In 2005 the central government decided to implement a proposal^[27] to electrify the urban network at 25 kV AC, the same system as on the central NIMT;^[28] this included 35.7 km (22.2 mi) of the NIMT itself, from Britomart to just south of Papakura. Work on electrification of the Auckland network began in 2010; the first revenue electric services using AM class EMUs commenced on 28 April 2014 between Britomart and Onehunga on the Onehunga Line.^[29] The electrification project on the Auckland network, including the Auckland-Papakura section of the NIMT, was completed in July 2015, with all suburban services being electric. A diesel shuttle service runs on the non-electrified Pukekohe-Papakura section.^[30]

The future[edit]

The completion of Auckland's electrification leaves a gap of 87.1 km (54.1 mi) to the central NIMT electrification at Te Rapa, north of Hamilton. Electrification may be extended south as the Auckland suburban system expands, but this will depend on further government funding. In February 2008 former Auckland Regional Council Chairman Mike Lee suggested the initial electrification might be extended to Pukekohe, leaving a 60 km gap to Te Rapa.^[31] In 2012, in response to public submissions, the board of Auckland Transport decided to include an investigation into electrifying to Pukekohe to its 10-year programme.^[32] ATAP, Auckland's 2018-2028 plan provides for Pukekohe electrification, a third line from Westfield to Wiri and further new electric trains.^[33]

A paper written in 2008 for then railway infrastructure owner ONTRACK investigated the possibility of electrifying the remaining Papakura-Te Rapa gap between the Auckland urban system's terminus at Papakura on the NIMT and the central NIMT system, along with electrification of the East Coast Main Trunk to Tauranga;^[34] the report put the total cost of electrification at $860 million, with $433 million for the Papakura-Te Rapa section.^[34] It concluded that money would be better spent on grade and curvature easements, removing speed restrictions and increasing the length of passing loops.^[34]

In Wellington, there is an 80.8 km (50.2 mi) gap from Waikanae to the central NIMT electrification at Palmerston North. Since the extension of electrification to Waikanae in February 2012, there have been calls for the electrification to be extended by 15 km (9.3 mi) to Otaki.^[35] If this happens, there will be a 66 km (41 mi) gap; as the two electrification systems are different, multi-current locomotives or multiple units would be required for through electric working, should that gap be ever closed.

On 21 December 2016, KiwiRail announced their plan to withdraw from service, over a two year period, the EF class electric locomotives (the only electric rolling stock working the central electrified section) without replacing them;^[36] the reasons given for the decision included the fact that the EFs are now close to their end of life (approximately 30 years old) and suffer from frequent breakdowns (on average every 30,000 kilometres (19,000 mi) which is well below the expected breakdown-free service interval of 50,000 kilometres (31,000 mi)) and that having to change from a diesel locomotive to an electric one and back again at each end of the electrified section is labour-intensive, time-consuming and adds to costs. KiwiRail did not intend to de-electrify the section but would maintain it so that electric rolling stock could be reintroduced in the future.

On 30 October 2018, the Government announced that it is retaining the EF class electric locomotives, to help meet its long term emissions goals and boost the economy; the 15 remaining EF class locomotives will be refurbished by KiwiRail and will continue to run between Hamilton and Palmerston North.^[37]

Centennial[edit]

On 6 August 2008 at 9am, a train (which included 100-year-old carriage A^A1013, restored by the Mainline Steam Trust) departed Wellington in a re-enactment of the 7 August 1908 Parliamentary Special carrying the Prime Minister Sir Joseph Ward to Auckland,^[38] stopping overnight at Taihape and Taumarunui before continuing to Auckland. Tickets were by invitation only.

A series of stamps was issued to commemorate the centennial, see Stamps:

50c - Last Spike Ceremony Manganui-o-te-ao - a photo of actual event ^[39]
$1.00 - Taumarunui, 1958 - steam locomotive K^A 947 pulling into the old railway station.
$1.50 - Makatote Viaduct, 1963.^[40]
$2.00 - Raurimu Spiral, 1964.
$2.50 - The Overlander, Hapuawhenua Viaduct, 2003.

Infrastructure[edit]

The NIMT has been described as an "engineering miracle", with numerous engineering feats especially along the Rangitikei River and on the North Island Volcanic Plateau; this included the building of the famous Raurimu Spiral to allow trains to ascend the steep grade from the Whanganui River valley to the North Island Volcanic Plateau.

The NIMT includes 352 bridges and 14 tunnels;^[2] the major viaducts include three (North Rangitikei, South Rangitikei and Kawhatau) opened in 1981 for the Mangaweka deviation. Five viaducts are over 70 metres (230 ft) high. There are smaller viaducts at Taonui north of Ohakune,^[41] and Manganui-o-te-Ao and Mangaturutura.^[42]

The heights and lengths of the main viaducts are:^[43]

Name	Height	Length	Opened	Remarks
North Rangitikei	81 m or 266 ft	160 m or 525 ft	1981
Makatote	79 m or 259 ft	262 m or 860 ft	1908
South Rangitikei	78 m or 256 ft	315 m or 1,033 ft	1981
Kawhatau	73 m or 240 ft	160 m or 525 ft	1981
Makohine	73 m or 240 ft	229 m or 751 ft	1902
Toi Toi	58 m or 190 ft	66 m or 217 ft	1904
Hapuawhenua	45 m or 148 ft	284 m or 932 ft	1908	replaced 1987 ^[44]
Hapuawhenua	51 m or 167 ft	414 m or 1,358 ft	1987
Waiteti	36 m or 118 ft	127 m or 417 ft	1889	or Waitete, 130 m or 427 ft long ^[45]
Mangaweka	288 m or 945 ft	48 m or 157 ft	1903	superseded by Mangaweka deviation ^[41]

Rolling stock[edit]

Due to its high volume and high value of traffic to NZR and the steep grades in the central section, the NIMT has used the most powerful locomotives in New Zealand.

When the NIMT opened in 1909, the powerful 4-8-2 X class was introduced to handle heavy traffic over the mountainous central North Island section. Four G class Garratt-type locomotives were introduced in 1928, but these locomotives were not as effective as anticipated. In 1932 the 4-8-4 K class was introduced, and later improved in 1939 with the K^A.

The introduction of the English Electric D^F class in 1954 began the end of the steam era, and in 1955 with the introduction of the D^A major withdrawals of steam locomotives began. 1972 saw the introduction of D^X locomotives and the Silver Fern railcars: the latter remained in service between Auckland and Wellington until 1991.

With electrification and the introduction of the EF class electric locomotives in the late 1980s, the DX class was mainly reassigned to other areas of the network, including hauling coal on the Midland Line in the South Island. Since then services between Te Rapa and Palmerston North have been worked mainly by the electrics, although some services are still diesel operated, such as those originating from or terminating on other lines, or originating from within the central section, like the paper pulp freight trains from Karioi.

As of May 2016, regular rolling stock on the NIMT include:

Class	Type	Cars per set	Number	Operator	Routes	Built
FP/FT Matangi	EMU	2	83	Transdev Wellington	Wellington suburban services between Wellington and Waikanae	2010–12, 2015–16
AM	EMU	3	57	Transdev Auckland	Auckland suburban services on Eastern and Southern Lines	2012–15
ADL/ADC	DMU	2	10	Transdev Auckland	Auckland passenger services between Papakura and the town of Pukekohe	1982–85
S	carriage	8	8 (one set)	KiwiRail	Capital Connection services between Wellington and Palmerston North	1971–75
AK	carriage	6	6 (one set)	KiwiRail Scenic Journeys	Northern Explorer services between Wellington and Auckland Strand Station	2011–12

DC class - all sections
DFT class - all sections
DL class - all sections
DX class - all sections
EF class - Palmerston North to Te Rapa

Connecting lines[edit]

Line Name	Date Opened	Date Closed	NIMT Junction	Terminus	Length	Notes
Newmarket Line	24/12/1873	Open	Quay Park Junction	Newmarket Junction	2.5 km	Formerly Auckland-Onehunga line 1873-1877, Auckland-Waikato line 1877-1908, NIMT 1908-1974.
North Auckland Line	20/5/1875	Open	Westfield Junction	Otiria Junction	280 km	Formerly formed part of the NIMT in conjunction with what is now the Newmarket Line.
Manukau Branch	15/4/2012	Open	Wiri Junction	Manukau	2.5 km
Mission Bush Branch	10/12/1917	Open	Paerata Junction	Mission Bush	17 km	Formerly Waiuku Branch. Glenbrook Vintage Railway uses the 8 km Glenbrook-Waiuku section.
Kimihia Branch		21/10/2015^[46]	Huntly North	Kimihia Mine	2.75 km
Rotowaro Branch	20/12/1915	Open	Huntly	Rotowaro	8.5 km	Formerly Glen Afton Branch (14 km long). Bush Tramway Club uses the 2 km section Pukemiro to Glen Afton.
Waipa Railway and Coal Co. line	1/3/1914	19/5/1958	Ngaruawahia	Wilton Collieries	10.5 km	Private line. Operated by NZR from 12/8/1935 to closure.
East Coast Main Trunk	20/10/1879	Open	Frankton Junction	Kawerau	180 km	Formerly Thames Branch (1879-1928). Line reduced in length by Kaimai Deviation, 1978. Former length 230 km.
Stratford–Okahukura Line	4/9/1933	Mothballed 2009	Okahukura Junction	Stratford	144 km	Leased to Forgotten World Adventures Ltd.
Raetihi Branch	18/12/1917	1/1/1968	Ohakune Junction	Raetihi	13 km
Marton–New Plymouth Line	4/2/1878	Open	Marton Junction	Breakwater (New Plymouth)	212 km
Taonui Branch	17/11/1879	14/8/1895	Taonui	Colyton	3.5 km
Palmerston North–Gisborne Line	9/3/1891	Open	Roslyn Junction	Gisborne	391 km	Napier-Gisborne section mothballed 2012. Gisborne City Railway use Gisborne-Muriwai section (16 km)
Foxton Branch	April 1873	18/7/1959	Longburn Junction	Foxton	31 km	Part of Foxton-New Plymouth Railway until 1908
Wairarapa Line	14/4/1874	Open	Distant Junction (Wellington)	Woodville	170 km	Reduced in length by closure of Rimutaka Incline (1955) from 182 km.
Johnsonville Branch	24/9/1885	Open	Wellington Junction	Johnsonville	10 km	Built by the Wellington and Manawatu Railway Company. 6 km Johnsonville-Tawa section closed 19/6/1937.
Te Aro Branch	27/3/1893	23/4/1917	Wellington (Lambton)	Te Aro	1.77 km

Notable connecting tramways and other lines[edit]

Junction Station	Date Opened	Date Closed	Owner	Notes
Drury	1862	unknown	Drury Coal Company	Horse tramway
Kellyville			Public Works Department	Construction of Pokeno to Paeroa line, not completed beyond Mangatawhiri.
Ngaruawahia	1/3/1914	19/5/1958	Waipa Railway and Coal Co.	10 km private railway.
Otorohonga		1921	Rangitoto Colliery Co.	6 km horse tram
Mangapehi		1944	Ellis and Bernand	Steam-powered bush tramway
Waione Siding		1950	Marton Sash and Door Co	Steam-powered bush tramway
Ongarue		1956	Ellis and Bernand	Extensive steam-powered bush tramway (now part of a cycle trail)
Taringamotu	1910	1960s	Taringamotu Tramway	Steam-powered bush tramway
Manunui		1944	Ellis and Bernand	Extensive steam-powered bush tramway
Oio		1935	King Speirs and Co	Steam-powered bush tramway
Mansons Siding			Manson and Clark	Steam-powered bush tramway
Raurimu		1935	King Speirs and Co	Steam-powered bush tramway
Raurimu	1935	1957	Raurimu Sawmilling Co	Steam-powered bush tramway
Pokaka	1930	1957	Pokaka Timber Co	Steam-powered bush tramway
Horopito			Horopito Sawmills Ltd	Highest railway in New Zealand, summit at 923.5 metres above sea level.
Longburn	27/10/1886	7/12/1908	Wellington and Manawatu Railway Company	Private line, purchased by NZR and incorporated into NIMT

Passenger services[edit]

Long-distance[edit]

From opening there have been regular passenger services between Wellington and Auckland; the daily "Express" left earlier in the evening, followed by the "Limited", which had fewer stops for passengers.

Between 1963 and 1968 daytime trains were called the Scenic Daylight. In 1968, an RM class 88-seater railcar was refurbished and repainted in a distinctive blue scheme that led to it being nicknamed the Blue Streak, it initially operated an unsuccessful service between Hamilton and Auckland in early 1968, and was transferred to the Auckland-Wellington run on 23 September 1968.

A DC hauls the now replaced Overlander long-distance passenger train between Auckland and Wellington.

In 1971 NZR introduced the Silver Star, a luxury sleeper train; the service was not economically viable, and was withdrawn in 1979. Much more successful was the Silver Fern, a daytime railcar service, introduced in 1972 to replace the "Blue Streak"; this service was withdrawn in 1991 and replaced by The Overlander.

In conjunction with the introduction of the carriage train Overlander service, the Silver Fern railcars were redeployed to start new services between Tauranga and Auckland - Kaimai Express, and Auckland and Rotorua - Geyserland Express, in 1991. In 2000 a new commuter service called the Waikato Connection was introduced between Hamilton and Auckland and ran in conjunction with the services to Tauranga and Rotorua until all three services were cancelled in 2001.

On 25 July 2006 Toll announced that the Overlander would cease at the end of September 2006, but on 28 September 2006 the train's continuation on a limited timetable was announced,^[47] it ran daily during the summer months and thrice-weekly for the balance of the year.

In 2012 KiwiRail announced the Overlander would be replaced by the Northern Explorer, with new AK class carriages to provide a premium tourist train on a quicker timetable with fewer stops, it commenced on Monday 25 June 2012, and consists of one train running from Auckland to Wellington on Mondays, Thursdays and Saturdays, and Wellington to Auckland on Tuesdays, Fridays and Sundays. It has fewer stops than the Overlander, stopping only at Papakura, Hamilton, Otorohanga, National Park, Ohakune, Palmerston North and Paraparaumu.

The Capital Connection commuter train operates between Palmerston North and Wellington.

Both KiwiRail and private enthusiast operators such as the Railway Enthusiasts Society, Mainline Steam and Steam Inc operate charter trains.

Auckland suburban[edit]

The northern terminus of the NIMT, Britomart Transport Centre.

Suburban trains run on the NIMT at regular intervals as follows:

Eastern Line (Manukau to Britomart via Glen Innes) trains run on the NIMT between Puhinui and Britomart.

Southern Line (Papakura to Britomart via Otahuhu and Newmarket) trains run on the NIMT from Papakura to Westfield Junction, they then run on the North Auckland Line to Newmarket, and the Newmarket Line to the vicinity of Quay Park, where they rejoin the NIMT only for the short section (about 500 metres) into Britomart. A diesel train shuttle service runs on the NIMT between Pukekohe and Papakura.

Onehunga Line and Western Line trains use the NIMT only for the short section (about 500 metres) from the vicinity of Quay Park into Britomart.

Wellington suburban[edit]

The southern terminus of the North Island Main Trunk, Wellington railway station, and busiest station in the Wellington suburban network.

Wellington's Metlink suburban network, operated by Transdev Wellington, includes the southern portion of the NIMT between Wellington and Waikanae as the Kapiti Line.

Stations[edit]

^[48]^[49]

Station	Distance from Wellington	Height above sea level (m)	Opened	Closed	Notes
Wellington	0 km	2.4m	1937	Open	Replaced NZR's Lambton and WMR's Thorndon stations, which closed upon completion.
Lambton	0 km	2.4m	1884	1937	Slightly north of current Wellington station.
Pipitea	0.75 km	2.4m	1874	1884	Original Wellington station, on Pipitea Quay.
Thorndon	0.75 km	2.4m	1886	1937	Wellington and Manawatu Railway Company, near of Pipitea station
Kaiwharawhara	2.44 km	2.4m	1874	2013	Kaiwarra until 1951.
Takapu Road	11.78 km	41m	1937	Open
Redwood	13.16 km	26.5m	1963	Open
Tawa	13.58 km	25.6m	1937	Open	Tawa Flat (closed 1937) was 12 metres above Redwood station on adjacent hillside.
Linden	14.85 km	17.7m	1940	Open
Kenepuru	16.16 km	15m	1940	Open
Porirua	17.8 km	3.6m	1885	Open
Paremata	21.7 km	2.7m	1885	Open
Mana	23.04 km	3m	1949	Open	Dolly Varden until 1960.
Plimmerton	24.4 km	5.8m	1885	Open
Pukerua Bay	30.1 km	80m	1885	Open
Muri	31.15 km	77m	1952	2011
Paekakariki	38.84 km	7m	1886	Open
Wainui	40.85 km	9m	1886	1900
Paraparaumu	48.28 km	13.7m	1886	Open
Otaihunga	51.5 km	21m	1886	1902
Waikanae	55.31 km	31m	1886	Open
Hadfield	60 km	39m	1886	1906
Te Horo	64.77 km	19.2m	1886	1965
Hautere	67.6 km	15.2m	1886	1900
Otaki	70.28 km	14.6m	1886	Open
Manakau	79.3 km	30.5m	1886	1967	Known as "Manukau" until 1905.
Ohau	84.95 km	30.7m	1886	c.1970
Levin	90.3 km	36.5m	1886	Open	Known as "Weraroa" 1886-1894.
Queen Street	91.37 km	36.5m	1956	c.1970
Levin	91.5 km	36.5m	1886	1894
Koputaroa	99.23 km	8.5m	1886	c.1970	Kereru until 1906.
Shannon	106.57 km	12.2m	1886	Open
Makerua	111.84 km	7.62m	1886	c.1970
Tokomaru	118.35 km	17.7m	1886	closed
Linton	124.19 km	18.3m	1886	closed
Longburn	129.69 km	19.8m	1873	closed
Awapuni	132 km	24.7m	1876	1965
Palmerston North	135.76 km	30m	1873	1965
Palmerston North	136.03 km	28m	1963	Open
Terrace End	138.51 km	38.1m	1876	1964
Bunnythorpe	144.47 km	55.2m	1876	1985
Taonui	148.62 km	61.9m	1876	1963
Aorangi	150.66 km	70.7m	1876	1965
Feilding	152.98 km	72.2m	1876	2012	except for groups of 10+^[50]
Makino Road	156.26 km	103m	1878	1960
Maewa	158.34 km	107m	1878	1962
Halcombe	165.76 km	118m	1878	closed
Kakariki	171.12 km	70m	1878	closed
Greatford	175.67 km	104.5m	1878	c.1970
Marton	180.25 km	140.8m	1878	2012	except for groups of 10+^[50]
Cliff Road	183.58 km	159.7m	1888	1966
Overton	188.85 km	155m	1888	1958
Porewa	190.53 km	165m	1888	closed
Rata	195.46 km	194m	1888	1975
Silverhope	199.31 km	224m	1888	1966
Hunterville	205.33 km	267m	1888	1986
Kaikarangi	210.18 km	284m	1888	1964
Mangaonoho	216.04 km	257m	1893	1966
Ohingaiti	222.14 km	279m	1902	1975
Mangaweka	231.04 km	326.7m	1902	1982
Utiku	243.69 km	371m	1904	closed
Ohotu	247.08 km	395.6m	1904	closed
Winiata	249.02 km	415m	1904	closed
Taihape	251.85 km	442m	1904	2012	except for groups of 10+^[50]
Mataroa	260.88 km	530m	1907	closed	photo of opening day
Ngaurukehu	270.25 km	640m	1908	closed
Turangarere	274.5 km	702m	1912	1972
Hihitahi	278.2 km	741m	1908	closed	Turangarere until 1912. "Hihitahi" is a sound-based local Maori word for "locomotive".
Waiouru	290.3 km	813.8m	1908	2005	Highest railway station in New Zealand.
Tangiwai	299.49 km	699.5m	1909	closed	Nearest station to the Tangiwai disaster, 24 December 1953.
Karioi	306.94 km	630.3m	1909	closed
Rangataua	312.79 km	670m	1909	closed
Ohakune	317.09 km	618.4m	1908	open	Ohakune Junction in working timetables 1917-1968.
Horopito	326.91 km	752m	1909	1981	Used as location for Smash Palace movie, 1981
Pokaka	332.57 km	811m	1909	closed
Erua	340.13 km	742.5m	1908	closed
National Park	346.83 km	806.8m	1908	open	Waimarino until 1949.
Raurimu	358.31 km	589m	1908	closed
Oio	366.25 km	520m	1908	closed	Known to WW2 American servicemen as "Zero-10". Shortest station name in the North Island, with Ava.
Owhango	371.89 km	456.6m	1908	closed
Kakahi	382 km	266m	1908	closed
Piriaka	387.15 km	230m	1908	closed
Manunui	391.9 km	190.5m	1908	closed
Matapuna	394.8 km	180m	1908	closed
Taumarunui	397.75 km	171m	1903	2012	except for groups of 10+^[50]
Taringamotu	402 km	172.5m	1903	1971
Okahukura	408.54	178.3m	1903	closed	Okahukura Junction in working timetables 1933-2010.
Te Koura	412.75 km	182m	1909	1975
Ongarue	420.68 km	192.6m	1903	1986
Waione Siding	426.86 km	208m	1921	1950
Waimiha	434.39 km	232m	1903	1983
Poro-O-Tarao	444.05 km	339.2m	1901	1979
Mangapehi	449.47 km	285.3m	1901	1984	Known as "Mangapeehi" station 1901-1920.
Kopaki	454.35 km	265m	1901	closed	Paratikana until 1920.
Puketutu	461.83 km	206m	1889	closed	Mokau" until 1912.
Waiteti	470.07 km	135m	1889	closed
Te Kuiti	475.66 km	54m	1887	2012	except for groups of 10+^[50]
Te Kumi	478.56 km	49.6m	1887	1968
Hangatiki	485.2 km	39.9m	1887	1982
Otorohanga	494.41 km	37m	1887	2012	Reopened summer 2012
Kiokio	498.45 km	35.4m	1887	1973
Te Kawa	506.88 km	47.8m	1887	1982
Te Mawhai	513 km	35.6m	1887	1958	Te Puhi until 1900
Te Awamutu	517.02 km	50m	1880	2005
Ngaroto	519.92 km	56m	1880	1954
Lake Road	522.26 km	54m	1880	1940
Ohaupo	527.16 km	52m	1880	1982
Rukuhia	533.59 km	55m	1880	1970
Hamilton	542.52 km	37.5m	1877	Open	Previously Hamilton Junction and Frankton Junction.
Te Rapa Racecourse	547.50 km	33.2m	1920	1980
Te Rapa	549.25 km	33m	1877	1970	Not to be confused with Te Rapa Marshalling Yards (547 km from Wellington).
Horotiu	553.65 km	23.7m	1877	c1968	Pukete until 23 June 1907.^[51] Moved from 77 mi (124 km) to 76 mi (122 km) from Auckland in 1880^[52]
Ngaruawahia	559.16 km	20.7m	1877	c1968	Newcastle until 1878.^[53]
Taupiri	566.56 km	13.7m	1877	c1968
Huntly	573.87 km	14m	1877	1998
Kimihia	578.45 km	14m	1877	1939
Ohinewai	582.04 km	10m	1877	c1968
Rangiriri	588.11	9m	1877	1957
Te Kauwhata	591.62 km	12.2m	1877	1984
Whangamarino	598.34 km	6.7m	1877	1978
Amokura	604.53 km	7m	1877	1980
Mercer	609.16 km	6.4m	1877	1986
Pokeno	613.96 km	24m	1877	c1968
Whangarata	617.90 km	59.7m	1877	c1968	a flag station^[54]
Tuakau	621.41 km	37m	1875	1986	rebuilt 1910^[55]
Buckland	625.6 km	58m	1875	closed
Pukekohe	628.86 km	60.65m	1875	open
Paerata	633.29 km	45.1m	1875	1980	Paerata Junction from 1917.
Runciman	638.37 km	8m	1875	1918
Drury	640 km	9m	1875	1980
Opaheke	642.9 km	14.5m	1875	1955	Hunua 1877-1939.
Papakura	647.02 km	19.2m	1875	Open
Tironui	648.95 km	15.5m	1904	1980
Takanini	650.64 km	15.2m	1875	Open
Te Mahia	652.24 km	14.9m	1904	Open
Manurewa	653.1 km	17m	1875	Open
Homai	655.7 km	30.78m	1904	Open
Wiri	657.6 km	22.25m	1913	2005
Puhinui	658.92 km	19.8m	1904	Open
Papatoitoi	659.63 km	18.9m	1875	1904
Papatoetoe	660.42 km	18m	1904	Open
Middlemore	662.28 km	8.8m	1904	Open
Mangere	663.02 km	10.66m	1904	2011
Otahuhu	664.15 km	9.44m	1875	Open
Westfield	665.5 km	7.6m	1904	2017
Sylvia Park	667.09 km	7.6m	1931	Open	Relocated 1 km further north, 2007.
Panmure	669.93 km	17.7m	1931	Open	Relocated 200m north, 2007.
Tamaki	671.28 km	23.5m	1930	1980
Glen Innes	672.64 km	22m	1930	Open
Purewa	675.4 km	18m	1930	1955
Meadowbank	676.26 km	12m	1954	Open
Orakei	677.44 km	4.5m	1930	Open
The Strand	680.76 km	2.7m	1930	Open	Was platform 7 of the 1930-2003 Auckland station. Terminus for the Northern Explorer long distance service and steam and other excursion services.
Britomart Transport Centre	682 km	4m below sea level	2003	Open	Terminus for Auckland suburban electric services only.

Record runs[edit]

Record runs from Auckland to Wellington were the 1960 Moohan Rocket (train) of 11 hours 34 minutes in 1960, and the Standard railcar time of 9 hours 26 minutes (running time 8 hours 42 minutes) in 1967.