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76-401: The Manukau Branch is a 2.5 kilometres (1.6 mi) spur railway line off the North Island Main Trunk railway from Wiri to Manukau City Centre in Auckland , New Zealand. It is the first fully new section of railway line constructed in Auckland since the Eastern Line in 1930. From Manukau, the branch connects to the NIMT in the north facing direction only. The estimated cost of

152-595: A spiral built to overcome large elevation differences with grades suitable for steam engines, the ruling gradient being 1 in 50. When the first sections of the NIMT were built, there was great uncertainty as to even the route in Waikato , with Cambridge , Kihikihi , Te Awamutu and Alexandra considered as possible destinations in Waikato. The central section was gradually extended to meet up in 1909, 23 years after

228-440: A variable voltage, variable frequency inverter using IGBTs with pulse-width modulation ) to run the motors. The system works in reverse for regenerative braking . The choice of 25 kV was related to the efficiency of power transmission as a function of voltage and cost, not based on a neat and tidy ratio of the supply voltage. For a given power level, a higher voltage allows for a lower current and usually better efficiency at

304-533: A cost of approximately $ 1 million, and another $ 4–5 million would be required to reconfigure the Ports of Auckland/KiwiRail sidings which were built to a design that conflicts with the proposed southern link. The branch has one railway station, Manukau train station , the terminus in Manukau City Centre. The station is intended to move more people into Manukau Central , an area identified by council as

380-767: A future metropolitan centre. The station is in (and accessed via) a 300 metres (980 ft) long trench, similar to the New Lynn station , to ease passage under nearby roads. A total of 47,000m of earth had been excavated when earthworks finished in May 2010. The station is located at the heart of a campus for the Manukau Institute of Technology , being below ground level with the campus building constructed above it. The branch opened on 15 April 2012. After several months in operation, during June 2012 daily usage levels were around 500 to 600 passengers. In April 2018, Manukau

456-554: A modern concrete structure, though the original has been restored as a tourist attraction. 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

532-725: 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

608-783: 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

684-534: A utility frequency system dates back to 1931, tests having run since 1922. It was developed by Kálmán Kandó in Hungary, who used 16 kV AC at 50 Hz , asynchronous traction, and an adjustable number of (motor) poles. The first electrified line for testing was Budapest–Dunakeszi–Alag. The first fully electrified line was Budapest–Győr–Hegyeshalom (part of the Budapest–Vienna line). Although Kandó's solution showed

760-599: A way for the future, railway operators outside of Hungary showed a lack of interest in the design. The first railway to use this system was completed in 1936 by the Deutsche Reichsbahn who electrified part of the Höllentalbahn between Freiburg and Neustadt installing a 20   kV   50 Hz AC system. This part of Germany was in the French zone of occupation after 1945. As a result of examining

836-518: A year after the last major battle. 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

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912-479: Is corrected by connecting each feeder station to a different combination of phases. To avoid the train pantograph bridging together two feeder stations which may be out-of-phase with each other, neutral sections are provided at feeder stations and track sectioning cabins. SVCs are used for load balancing and voltage control. In some cases dedicated single-phase AC power lines were built to substations with single phase AC transformers. Such lines were built to supply

988-427: Is doubled to 50 kV to obtain greater power and increase the distance between substations. Such lines are usually isolated from other lines to avoid complications from interrunning. Examples are: The 2 × 25   kV autotransformer system is a split-phase electric power system which supplies 25   kV power to the trains, but transmits power at 50   kV to reduce energy losses. It should not be confused with

1064-607: Is ideal for railways that cover long distances or carry heavy traffic. After some experimentation before World War II in Hungary and in the Black Forest in Germany , it came into widespread use in the 1950s. One of the reasons it was not introduced earlier was the lack of suitable small and lightweight control and rectification equipment before the development of solid-state rectifiers and related technology. Another reason

1140-716: 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 . Following the Second World War railway services suffered due to skill and coal shortages. Skilled staff sought employment opportunities elsewhere in

1216-641: 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, built to the New Zealand rail gauge of 1,067 mm ( 3 ft 6 in ) and serves the large cities of Palmerston North and Hamilton . Most of the NIMT is single track with frequent passing loops , but sections at each end also handling suburban commuter traffic are double tracked. The section known as

1292-400: Is then fed, sometimes several kilometres away, to a railway feeder station located beside the tracks. Switchgear at feeder stations, and at track sectioning cabins located halfway between feeder stations, provides switching to feed the overhead line from adjacent feeder stations if one feeder station loses grid supply. Since only two phases of the high-voltage supply are used, phase imbalance

1368-551: The King Country was not accessible to Europeans until 1883. 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

1444-823: The North-South Junction between Wellington and Waikanae , except for 3.3 km (2.1 mi) of single-track through tunnels between North Junction (35.3 km (21.9 mi) from Wellington) and South Junction, (32 km (20 mi) from Wellington), on the Pukerua Bay to Paekākāriki section, Around 460 km (290 mi) (approximately 65%) of the line is electrified in three separate sections: one section at 1500 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 Pukekohe and Auckland Waitematā. The first section of what became

1520-616: 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, with a first sod event near Koheroa on Tuesday, 29 March 1864 by Auckland's Chief Superintendent of Roads & Bridges, W R Collett . Turning of the first sod of the Auckland and Drury Railway took place in 1865,

1596-691: The war delayed most of these works for over a decade. In 1927, automatic colour-light signalling was installed from Otahuhu to Mercer. 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, followed by 9 mi 12 ch (14.7 km) Ngāruawāhia to Huntly on 4 December 1938 and Huntly to Ohinewai and Papakura to Paerata in December 1939. By then, wartime shortages delayed further double-tracking. Pokeno to Mercer

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1672-493: 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

1748-520: The 1960s. The main reason why electrification using utility frequency had not been widely adopted before was the lack of reliability of Mercury arc rectifiers that could fit on the train. This in turn related to the requirement to use DC series motors , which required the current to be converted from AC to DC and for that a rectifier is needed. Until the early 1950s, mercury-arc rectifiers were difficult to operate even in ideal conditions and were therefore unsuitable for use in railway locomotives. It

1824-438: The 1990s, as they can be controlled by voltage, and have an almost ideal torque vs speed characteristic. In the 1990s, high-speed trains began to use lighter, lower-maintenance three-phase AC induction motors. The N700 Shinkansen uses a three-level converter to convert 25 kV single-phase AC to 1,520 V AC (via transformer) to 3 kV DC (via phase-controlled rectifier with thyristor) to a maximum 2,300 V three-phase AC (via

1900-413: The 50   kV system. In this system, the current is mainly carried between the overhead line and a feeder transmission line instead of the rail. The overhead line (3) and feeder (5) are on opposite phases so the voltage between them is 50   kV, while the voltage between the overhead line (3) and the running rails (4) remains at 25   kV. Periodic autotransformers (9) divert the return current from

1976-613: The French TGV . Railway electrification using 25 kV , 50 Hz AC has become an international standard. There are two main standards that define the voltages of the system: The permissible range of voltages allowed are as stated in the above standards and take into account the number of trains drawing current and their distance from the substation. This system is now part of the European Union's Trans-European railway interoperability standards (1996/48/EC "Interoperability of

2052-641: The German system in 1951 the SNCF electrified the line between Aix-les-Bains and La Roche-sur-Foron in southern France, initially at the same 20   kV but converted to 25   kV in 1953. The 25   kV system was then adopted as standard in France, but since substantial amounts of mileage south of Paris had already been electrified at 1.5   kV DC , SNCF also continued some major new DC electrification projects, until dual-voltage locomotives were developed in

2128-630: The Minister of Public Works William Hall-Jones instigated a night shift (under kerosene lamps). 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. The gap

2204-667: 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. The central section from Te Rapa near Hamilton to Palmerston North

2280-690: 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, and for having opened up the centre of the North Island to European settlement and investment. In the early days, a passenger journey between Wellington and Auckland could take more than 20 hours; today, it takes approximately 11 hours. The NIMT has been described as an "engineering miracle", with numerous engineering feats such as viaducts , tunnels and

2356-479: The NIMT which are electrified: Auckland's urban network and the central section (25 kV AC) from Palmerston North – Te Rapa (north of Hamilton) at 25 kV AC . Wellington's urban network is electrified at 1500 V DC; as formerly used in other sections of the New Zealand network. In Wellington the operating voltage has been increased to 1650V DC, and 1700V DC since the full introduction of the Matangi EMU , to increase

Manukau Branch - Misplaced Pages Continue

2432-559: The NIMT, the General Motors G12 export models were ordered, becoming the D class . The 411 km (255 mi) section between Palmerston North and Hamilton was electrified at 25 kV 50 Hz AC , opened on 24 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

2508-606: The NIMT. 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. 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. In 1913,

2584-620: 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). In the Auckland area, a third main line between Wiri and Westfield is under construction; this will allow freight (or other) trains to bypass stationary passenger trains. There are three independent sections of

2660-714: The Trans-European high-speed rail system" and 2001/16/EC "Interoperability of the Trans-European Conventional rail system"). Systems based on this standard but with some variations have been used. In countries where 60 Hz is the normal grid power frequency, 25 kV at 60 Hz is used for the railway electrification. In Japan, this is used on existing railway lines in Tohoku Region , Hokuriku Region , Hokkaido and Kyushu , of which Hokuriku and Kyushu are at 60   Hz . Some lines in

2736-544: The United States have been electrified at 12.5 kV 60 Hz or converted from 11 kV 25 Hz to 12.5 kV 60 Hz . Use of 60 Hz allows direct supply from the 60   Hz utility grid yet does not require the larger wire clearance for 25 kV 60 Hz or require dual-voltage capability for trains also operating on 11 kV 25 Hz lines. Examples are: Early 50   Hz AC railway electrification in the United Kingdom

2812-493: The branch's earthworks. The extension of State Highway 20 to State Highway 1 included provision for the route. Following the opening of the branch, Auckland mayor Len Brown called for the completion of its south facing link to the North Island Main Trunk. The earthwork formation (constructed by NZTA at a cost of approximately $ 25 million) for such a link is in place, but tracks need to be laid for it at

2888-532: The coal shortage and prevent heavy 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. Aickin 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

2964-570: 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. The Royal Commission on Railways created following Aickin's tenure rejected the report's findings. Aickin's successor Horace Lusty , revised the contract with English Electric to specify D class diesel-electric locomotives . They were later found to be unreliable, and only ten were supplied. 42 D class locomotives were supplied instead for secondary lines. For main lines including

3040-503: 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 kV AC railway electrification This electrification

3116-571: The economy. From 1948 to 1951 the General Manager of the Railways Department , Frank 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

Manukau Branch - Misplaced Pages Continue

3192-533: The edge of the city. 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. The viaducts were at the end of their economic lives. The deviation removed a number of tunnels, many of which were built in unstable country, and eliminated a number of steep gradients. A combined road and rail deviation had bean considered with

3268-525: 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. Routes via Napier and Waitara were also considered, with surveying in Taranaki from 1883 to 1889. Construction of the final central section began on 15 April 1885, when paramount chief Wahanui of Ngāti Maniapoto turned

3344-676: 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 . 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,

3420-431: 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

3496-447: The greater cost for high-voltage equipment. It was found that 25 kV was an optimal point, where a higher voltage would still improve efficiency but not by a significant amount in relation to the higher costs incurred by the need for larger insulators and greater clearance from structures. To avoid short circuits , the high voltage must be protected from moisture. Weather events, such as " the wrong type of snow ", have caused failures in

3572-401: 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). Signalling on

3648-400: The last of the northern and southern sections of NIMT had been opened. Auckland's first railway was the 13 km (8.1 mi) line between Point Britomart and Onehunga via Penrose, opened in 1873. It was built by Brogdens , as was the rest of the Auckland & Mercer Railway, for £166,000 for the 41 mi (66 km) to Mercer . The section from Penrose to Onehunga is now called

3724-411: The late 1930s, bridges replaced level crossings at Ohinewai, Taupiri and Hopuhopu . 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

3800-625: The line linking the ports of Foxton and Whanganui . 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. From Te Awamutu, it was proposed that the line be built via Taupo or via Taumarunui ,

3876-555: 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. 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

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3952-542: 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. Under Thomas Ronayne , the New Zealand Railways Department general manager from 1895 to 1913, 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

4028-757: 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). 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

4104-606: The neutral rail, step it up, and send it along the feeder line. This system was initially deployed on France's then new Paris-Lyon High speed rail line in 1981, and has gone on to be used by New Zealand Railways in 1988, Indian Railways , Russian Railways , Italian High Speed Railways, UK High Speed 1 , most of the West Coast Main Line and Crossrail , with some parts of older lines being gradually converted, French lines (LGV lines and some other lines ), most Spanish high-speed rail lines, Amtrak and some of

4180-500: The north express from Wellington to Ohakune, then transferred to the southbound express, so avoiding the heavy gradients of the central section. 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

4256-486: The past. An example of atmospheric causes occurred in December 2009, when four Eurostar trains broke down inside the Channel Tunnel . Electric power for 25 kV AC electrification is usually taken directly from the three-phase transmission system . At the transmission substation, a step-down transformer is connected across two of the three phases of the high-voltage supply and lowers the voltage to 25 kV . This

4332-553: The power available. 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

4408-535: The project was $ 50 million. Construction began in June 2008 with completion expected in late 2011. However, due to other work on the Auckland network taking priority, completion was rescheduled for April 2012. Station works were reported essentially finished by October 2011, and the line opened on 15 April 2012. The branch leaves the NIMT south of Puhinui station and slightly north of the closed Wiri station . It runs on both New Zealand Railways Corporation and Auckland Council land. The NZ Transport Agency built some of

4484-741: 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 in 1915. Similar work was done to ease the gradient to Greatford, on the other side of the Rangitīkei River, in 1939. 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, but

4560-676: 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

4636-565: 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

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4712-587: 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 North-South Junction section 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

4788-535: The system and Aickin 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. Aickin later fell out with

4864-402: 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

4940-462: 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 is a travelling power station, the savings through electrification compared to diesel could be regarded as the difference between

5016-466: 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

5092-600: 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. But much of the new section was temporary, with some cuttings north of Taonui having vertical batters and unballasted track from Horopito to Makatote. Ward drove the last spike on 6 November 1908, and

5168-603: 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. The construction of

5244-415: Was done using a steam engine beneath a bridge at Crewe . A section of 25 kV overhead line was gradually brought closer to the earthed metalwork of the bridge whilst being subjected to steam from the locomotive's chimney. The distance at which a flashover occurred was measured and this was used as a basis from which new clearances between overhead equipment and structures were derived. Occasionally 25 kV

5320-472: 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. Doubling of the section south of Amokura is being investigated in a business case from July 2021. In 1930, the Westfield deviation was opened, creating

5396-564: 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

5472-425: Was planned to use sections at 6.25 kV AC where there was limited clearance under bridges and in tunnels. Rolling stock was dual-voltage with automatic switching between 25 kV and 6.25 kV . The 6.25 kV sections were converted to 25 kV AC as a result of research work that demonstrated that the distance between live and earthed equipment could be reduced from that originally thought to be necessary. The research

5548-404: Was possible to use AC motors (and some railways did, with varying success), but they have had less than ideal characteristics for traction purposes. This is because control of speed is difficult without varying the frequency and reliance on voltage to control speed gives a torque at any given speed that is not ideal. This is why DC series motors were the most common choice for traction purposes until

5624-462: Was straightened in conjunction with the duplication by reclaiming land along the eastern shore of Porirua Harbour. In 1967, the floors of the tunnels on the former WMR section between Paekākāriki and Pukerua Bay were lowered to enable the D class locomotives to travel all the way to Wellington. Between 1964 and 1966, a deviation away from the centre of Palmerston North via the Milson deviation on

5700-466: Was the 11th busiest train station on the Auckland network with an average of 1,650 passengers on a typical weekday. On 7 April 2018, a 23-bay bus station was opened on a lot adjacent to the train station to create a transport hub serving most of the southern Auckland Region. Services from the facility began the following day. North Island Main Trunk The North Island Main Trunk ( NIMT )

5776-488: Was the increased clearance required under bridges and in tunnels, which would have required major civil engineering in order to provide the increased clearance to live parts. Where existing loading gauges were more generous, this was less of an issue. Railways using older, lower-capacity direct-current systems have introduced or are introducing 25 kV AC instead of 3 kV DC/ 1.5 kV DC for their new high-speed lines. The first successful operational and regular use of

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