Auckland to Te Awamutu

Auckland's first railway was the 13 km (8.1 mi) line between Point Britomart and Onehunga via Penrose, opened in 1873.^[7] It was built by Brogdens,^[8] as was the rest of the Auckland & Mercer Railway, for £166,000 for the 41 mi (66 km) to Mercer.^[9] The section from Penrose to Onehunga is now called the Onehunga Branch. The line was later continued south from Penrose into the Waikato. To support the Invasion of the Waikato, a 3.5 mi (5.6 km) tramway was built from Maungatāwhiri to Meremere in 1864,^[10] with a first sod event near Koheroa on Tuesday, 29 March 1864 by Auckland's Chief Superintendent of Roads & Bridges, W R Collett.^[11] Turning of the first sod of the Auckland and Drury Railway took place in 1865, a year after the last major battle.^[12] This line reached Mercer by 20 May 1875, with 29 km (18 mi) from Ngāruawāhia 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 negotiations with local Māori, and the King Country was not accessible to Europeans until 1883.^[13]

Wellington to Marton

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 government and merged with the New Zealand Railways Department in 1908.

The Longburn to Marton section had been opened on 18 April 1878, as part of the line linking the ports of Foxton and Whanganui.^[14]

Central North Island

Panorama of the Raurimu Spiral.

In 1882, the Whitaker Ministry passed the North Island Main Trunk Railway Loan Act, to expedite construction of the North Island Main Trunk south of Te Awamutu by authorising the overseas borrowing of a million pounds (probably in London) for the work.^[15] 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.^[16]

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.^[13] 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.

Richard Seddon’s Liberal Government pledged in 1903 that the whole route would be open in 1908. In 1904, the railheads were still 146 km (91 mi) apart, and contracts for three massive viaducts (Makatote, Hapuawhenua and Taonui) were not let until 1905. The government committed 2500 workmen, and in 1907, the Minister of Public Works William Hall-Jones instigated a night shift (under kerosene lamps).^[17] 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 of 27 km (17 mi) had not yet been handed over to the Railways Department.

Opening

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.^[2] But much of the new section was temporary, with some cuttings north of Taonui having vertical batters and unballasted track from Horopito to Makatote.^[18] 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.

Signals and track

The rails and signalling have been upgraded over the years, and many sections of the line have been deviated: The original 1870s Vogel Era track had rails of 40 lb/yd (19.9 kg/m), some were iron not steel; later rails were 53 lb/yd (26.3 kg/m); and from 1901 70 lb/yd (34.8 kg/m), e.g. between Taumarunui and Taihape for the heavy X class locomotives used on the central mountainous section from 1908. Some 10 bridges between Frankton and Taumarunui had to be strengthened, and in 1914 there was still 129 km (80 mi) of 53 lb/yd rail to be replaced. In the 1930s 85 lb/yd (42.2 kg/m) was adopted, then 91 lb/yd (45.1 kg/m), and from 1974 100 lb/yd (50 kg/m).^[19]

Signalling on the single-track sections (most of the line) was controlled by Tyer's Electric Train Tablet No 7 system; with each of the stations for the 94 tablet sections staffed by three tablet porters each working a 56-hour week for continuous coverage; hence each station required at least four houses for the stationmaster and three porters. Pierre noticed that with CTC station buildings and even platforms had been removed as there were no longer any staffed stations between Ohakune and National Park. The Train Control system introduced from 1928 to 1932 supplemented the tablet system by operators at the four sections (Auckland, Frankton, Te Kuiti, Ohakune, Marton and Wellington) to expedite operation of trains over several tablet sections; the 1925 Fay-Raven report urged its adoption because of the fitful progress of mixed trains, with locomotives often kept waiting. From 1938 to 1966 Centralised Traffic Control (CTC) gradually replaced the tablet system on the NIMT.^[20] In 1957 when the installation of CTC over the remaining 354 km (220 mi) commenced, it was estimated that using CTC over the 330 km (205 mi) Taumarunui to Otaki section with control centres at Ohakune (which shifted to Taumarunui in 1977), Taihape and Palmerston North would replace 74 men in traffic working duties. The last section converted was Piriaka-Owhango.^[21]

A 1926 article by "Backblocks" described conditions for staff at these stations where four workers lived in isolated areas, and their efforts to get special trains for transport to special events.^[22]

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.^[23] Under Thomas Ronayne, the New Zealand Railways Department general manager from 1895 to 1913,^[24] 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.^[25] On the Kakariki bank between Halcombe and Marton a deviation reduced the 1 in 53 grade to 1 in 70 in 1915.^[26] Similar work was done to ease the gradient to Greatford, on the other side of the Rangitīkei River, in 1939.^[27] 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,^[28] but the war delayed most of these works for over a decade.

In 1927, automatic colour-light signalling was installed from Otahuhu to Mercer.^[29] 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 December 1937,^[30] followed by 9 mi 12 ch (14.7 km) Ngāruawāhia to Huntly on 4 December 1938^[31] and Huntly to Ohinewai and Papakura to Paerata in December 1939.^[32] By then, wartime shortages delayed further double-tracking.^[33] Pokeno to Mercer was doubled from 11 November 1951, Pukekohe to Pokeno 21 November 1954, Mercer to Amokura 1 July 1956 and Ohinewai to Te Kauwhata 14 December 1958. The 13 km (8.1 mi) between Amokura and Te Kauwhata remain single track, as does Ngāruawāhia bridge.^[34] Doubling of the section south of Amokura is being investigated in a business case from July 2021.^[35]

Westfield deviation

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.^[36] 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.^[36]

In the late 1930s, bridges replaced level crossings at Ohinewai, Taupiri and Hopuhopu.^[37]

Tawa flat deviation

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 and twisting original route where long sections at 1 in 60 gradient required banker engines. The Wellington to Johnsonville section of the original line was retained as the Johnsonville Line and the Johnsonville to Tawa section closed.

The sections from Plimmerton to South Junction, north of Pukerua Bay and Muri, and North Junction to Paekākāriki were duplicated in 1940. From 24 July 1940 electrification at 1500 V DC of the southern section of the NIMT from Wellington to Paekākāriki was completed. The Tawa Flat deviation has a long tunnel (Tawa No 2) not suitable for steam operation because of excessive smoke (although steam trains were temporarily operated in the new deviation from 1935). A Centralised Train Control (CTC) system was installed in 1940, so that new signal boxes were not required and five stations between Tawa and Pukerua Bay no longer had to be continually staffed for Tablet operation; see Kapiti Line and North–South Junction. Electrification eliminated the need to relieve the steep (1 in 57) gradients from Plimmerton to the Pukerua Bay summit by a deviation to the east and allowed more frequent suburban passenger trains (and allowed suburban electric multiple units to run on this section from September 1949).

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

The difficult section down the Paekakariki Escarpment from Pukerua Bay to Paekākāriki with five 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.^[38]

In 1967, the floors of the tunnels on the former WMR section between Paekākāriki and Pukerua Bay were lowered to enable the D^A class locomotives to travel all the way to Wellington.

Milson deviation

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

Mangaweka deviation

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 Rangitīkei and Kawhatau rivers.^[39] The viaducts were at the end of their economic lives.^[40] The deviation removed a number of tunnels, many of which were built in unstable country,^[41] and eliminated a number of steep gradients.^[41]

A combined road and rail deviation had bean considered with the Ministry of Works, but was too expensive. In 1966 the NZR General Manager Alan Gandell said that the deviation would eliminate five old and narrow tunnels, and that New Zealand topography precluded a fast run, but travel time would be cut from 13½ hours to between 11½ and 12 hours, the best possible without tremendous expense. But two modern express trains were being designed for the NIMT, and should be introduced in three to four years.^[42]

Hapuawhenua deviation

The central section from Te Rapa near Hamilton to Palmerston North was electrified between 1984 and 1988 as part of the Think Big government energy program. 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.

Recent upgrades

In 1980 the 1880s Poro-O-Tarao Tunnel in the King Country was replaced by a tunnel with clearances which allowed for large hicube containers.

In 2009–10, the 1.5 km (0.93 mi) 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 Paekākāriki 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.^[43]

The construction of the Peka Peka to Otaki section of the Kāpiti Expressway required 1.3 km (0.81 mi) 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).^[44][45]

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 (or Papakura) is under construction;^[46] this will allow freight (or other) trains to bypass stationary passenger trains.^[47]

Future

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 kilometres (37 mi) gap to Te Rapa.^[56] 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.^[57] ATAP, Auckland's 2018–2028 plan provides for Pukekohe electrification, a third line from Westfield to Wiri and further new electric trains.^[58] In 2020 the government announced funding for electrification from Papakura to Pukekohe.^[59]

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.^[60] The report put the total cost of electrification at $860 million, with $433 million for the Papakura-Te Rapa section.^[60] It concluded that money would be better spent on grade and curvature easements, removing speed restrictions and increasing the length of passing loops.^[60]

In Wellington, there is an 80.8 km (50.2 mi) gap from Waikanae to the central NIMT electrification at Palmerston North. As the two electrification systems are different, multi-current locomotives or multiple units would be required for through electric working. Replacement rolling stock for Wellington, Wairarapa and Palmerston North and extending electrification north of Waikanae to Levin and beyond are being investigated in a business case from July 2021.^[35] KiwiRail has indicated it has no plans to upgrade the Wellington electrification from 1500 V DC to 25 kV AC, but intends to use dual-voltage locomotives.^[61] It has also indicated any extension north of Waikanae station would be at 25 kV AC, with through workings from Wellington to Ōtaki and further north requiring multi-current rolling stock; this would also allow the 25 kV AC section to be fed from the existing 220 kV substation at Paraparaumu, avoided the cost of building a new substation.^[62]

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.^[63] 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.^[64]

In 2021 the "North Island Electrification Expansion Study" was published by KiwiRail, Beca and Systra following a government grant for a business case.^[65][66] The report recommended electrification from Waikanae to Palmerston North be 25kV AC, with a change over just north of Waikanae to allow multi-current electric locomotives to switch between AC and DC traction.^[65] The cost of electrifying this section of the NIMT was at an expected estimate of $339m, with the Pukekohe to Te Rapa section estimated at $430m.^[66]