The North Auckland Line (designation NAL) is a major section of New Zealand's national rail network, and is made up of the following parts: the portion of the Southern Line that runs northward from Westfield to Newmarket; the portion of Auckland's Western Line that runs from Newmarket westward to Waitakere; the line that runs northward from Waitakere to Otiria via Whangarei. The first section was opened in 1868 and the line was completed in 1925.
No passenger services run between Westfield and Otiria or originate from those stations to anywhere else, because 'North Auckland Line' is merely a designation for the section of track, not a service route.
Three lines of Auckland's suburban rail network make use of the North Auckland Line. From Westfield Station to Newmarket Station, it forms part of the Southern Line. The Onehunga Line diverges from the Southern Line at Penrose, where it then follows the Onehunga Branch to its terminus at Onehunga. From Newmarket to Waitakere Station, the NAL is used by Western Line services. Trial commuter services from Helensville commenced in July 2008, but ceased on Christmas Eve 2009 due to lower patronage than had been expected.
The North Auckland Line previously continued to Opua in the Bay of Islands, with the section from Otiria to Opua sometimes known as the Opua Branch. It is now owned by the Bay of Islands Vintage Railway but regular operations have been suspended since 2001, with resumption on a short section of the line in 2008.
The North Auckland Line is currently under review as part of KiwiRail's turnaround plan. A proposed new branch line, the Marsden Point Branch, would serve Northland Port, a deepwater port at Marsden Point, by diverging from the North Auckland Line south of Whangarei at Oakleigh.
Three branch lines are on the line:The Onehunga Branch line connects with the North Auckland Line at Penrose and forms part of the route of Onehunga Line suburban passenger train services operating between Britomart and Onehunga via Newmarket.
The Newmarket Line meets the North Auckland Line in Newmarket and provides a connection with Britomart.
Further north, the Dargaville Branch branches off in Waiotira. The Dargaville Branch also boasted of a branch of its own, built by the Kaihu Valley Railway Co, and running northwestwards to Kaihu and Donnelly's Crossing.
The Okaihau Branch formerly left the North Auckland Line in Otiria and the Riverhead Branch in Kumeu.
It took many years to build a complete line to serve the Northland Region, with different sections being developed at different times. Eventually it became clear that a main line was required to link these isolated railways to improve transport for both passengers and freight to and from New Zealand's northernmost region, and to open up land for greater economic development. However, the construction was not without criticism. In 1910, the Minister of Railways himself criticised the project, arguing that the project of extending it would bring little benefit, as most traffic from north of Auckland was already covered by only going as far as Helensville, while country to the north was poor and would not be able to support the line.
Many sections of the line were considered technically challenging, especially the tunnels, construction of which had been called 'notorious' at the time.
The first section of what became the North Auckland Line opened as a private industrial line on 2 March 1868 between Kawakawa and a wharf at Taumarere. It was constructed not as a railway, but as a wooden-railed bush tramway to carry coal to the wharf for export, and was built to the international standard gauge of 4 ft 8 1⁄2 in (1,435 mm). The standard New Zealand track gauge, adopted a few years later, is 3 ft 6 in (1,067 mm) narrow gauge, but when the Kawakawa-Taumarere tramway was converted into a metal railway in 1870, it retained its gauge of 4 ft 8 1⁄2 in. In 1875, the government purchased the line and converted it to 3 ft 6 in gauge two years later.
The second portion of what became the North Auckland Line was built as a temporary measure. Timber interests around the Kaipara Harbour had poor access to markets in Auckland, so accordingly, a line was built overland from the Kaipara to a wharf in Riverhead for transshipment. The Auckland Provincial Council began construction on 31 August 1871, but on 1 January 1872, the central government took over work. Due to delays with acquiring rails, construction was delayed and the line did not open until 29 October 1875. The section from the shores of the Kaipara at a station named Helensville South to Kumeu became part of the North Auckland Line; the rest to Riverhead became a branch. This brief line cut transport costs and time in comparison to a bullock team or lengthy coastal shipping.
The discovery of coal in the Kamo area created a need for transportation from the mines to export wharves. The first mine opened in 1872, and as the 1870s progressed, mining activity increased and so did pressure for a railway. In 1877, the government approved a tramway, but a preliminary survey the next year found a tramway would be inadequate; accordingly, a railway was approved from Kamo to Whangarei. Construction began on 10 March 1879, but quickly fell behind schedule due to unstable terrain and slips. On 28 October 1880, the first 7.3 km of line opened, but this featured a temporary 1 km siding to an alternative wharf as the full line was completed to the intended wharf. At 10.64 km, the full line opened on 30 November 1882. The line in Whangarei was raised, the station moved and level crossings eliminated in 1925-26, when it was linked to the Helensville section.
The earliest Auckland portion, between Newmarket and Westfield, was actually built as part of the Onehunga Branch in 1873 and was only classified as part of the North Auckland Line at a later date. The first section of a line northwards from Auckland was not officially begun until later that decade, and work took place concurrently with the Whangarei - Kamo section. The first portion, from Newmarket to Glen Eden, opened without ceremony on 29 March 1880. On 21 December 1880, it was opened to Henderson, and on 13 July 1881, it was opened to Helensville. The extension to Helensville connected to the Kaipara - Riverhead Section; its northern terminus was extended from Helensville South to a more central Helensville station, and the portion from Kumeu to Riverhead was made redundant as it was quicker to convey goods by train directly to Auckland than transship them to ships at Riverhead. Accordingly, Kumeu - Riverhead was closed on 18 July 1881.
By the mid-1870s, the inadequacy of the Taumarere wharf was becoming apparent; accordingly, in 1876, plans were drawn up for a deepwater wharf and associated township named "Newport", later Opua. A railway was surveyed to link Kawakawa to Opua, and on 7 April 1884, it opened. It left the original line not far from the Taumarere wharf, relegating the short section from junction to Taumarere wharf to the status of spur. Both spur and wharf were made redundant by the new extension and accordingly closed the day of the opening to Opua.
In the latter half of the 1880s, impetus developed to link Kamo and Kawakawa. Surveys had already been undertaken in 1879 and 1883 for a line, but both times, government disapproval blocked construction. Ultimately, dispute about the fate of the Puhipuhi forest brought about the extension. Logging interests wished to chop down the forest, but lacked viable transportation to Whangarei so the timber could be exported; others wished to burn the forest so the land could be used for agriculture. In 1888, fires were started deliberately in the forest and it became obvious that considerable timber wealth would be lost if a railway were not built soon. The local member of parliament announced the construction of a tramway on 7 August 1889, but both that year and next, the Public Works Department (PWD) rebuffed him. In 1891, Whangarei interests established a syndicate to extend the line under the Railway Construction Act 1881, and their detailed offer prompted a newly elected government to act. The Railway Authorisation Act of 1891 approved the extension by transferring funds from a plan to duplicate the line from central Auckland to Penrose.
Initially, the syndicate was disappointed with the government's progress, as work did not commence until March 1892 due to a shortage of labour. However, by 2 July 1894, the line was opened to Waro. Locals believed this was the first part of the link to Kawakawa, but Richard Seddon had not authorised the full project, just the extension to the Puhipuhi forest. This was originally meant to terminate in Whakapara, but a further extension to Waiotu was required to provide easier access and this opened on 28 December 1898. A further extension to Hukerenui was requested, but it was delayed due to the failure of the Railway Authorisation Act of 1898 to pass parliament. Considerable political pressure was applied to close the gap between the Kawakawa and Whangarei sections as the road in between was poor and muddy, and the Railway Authorisation Act of 1899 accordingly authorised Waiotu - Hukerenui along with 8 km of line south from Kawakawa. The succeeding year's Act allowed for the construction of the remaining 24 km to complete the line via Otiria.
On 1 March 1901, the line was opened to Hukerenui, and by 1904, the PWD was able to run trains south of Kawakawa for 12.8 km. However, a lack of detailed surveys, poor finances, unstable terrain, and the PWD being overburdened with jobs contributed to a slow rate of progress. In May 1910, the 7 km section from Hukerenui to Towai was able to open, and the full section was finally completed the next year. It was handed over from the PWD to the New Zealand Railways Department on 13 April 1911, thus linking Whangarei to the Bay of Islands. Construction had cost nearly a million dollars.
With the completion of the line from Whangarei to Opua, the final remaining section of the North Auckland Line was the gap between Helensville and Whangarei. The first work on bridging this large gap occurred in the 1880s, when an extension from Helensville to Kanohi opened on 3 May 1889. Beyond this point, construction proved extremely difficult and slow due to the soft clay of the terrain. The 4.5 km between Kanohi and Makarau did not open until 12 June 1897, followed by another 5 km to Tahekeroa on 17 December 1900. The line then progressively opened in stages over the next ten years, reaching Wellsford on 1 April 1909 and Te Hana on 16 May 1910. The former became the site of a small locomotive depot, while the latter was established as the northernmost terminus for passengers until the full line was finished.
After 1908, the completion of the North Island Main Trunk Railway meant workers could be transferred north and this improved the rate of construction for a few years. In 1914, the longest bridge on the line, the Otamatea Bridge, was completed with a length of 313 m. However, the outbreak of World War I slowed construction. On 13 March 1913, the line had been opened to Kaiwaka, but the next section to Huarau, including the Otamatea Bridge, was not formally opened until 1 March 1920. At this point, work had also begun on a line south from Whangarei; it opened to Portland on 3 April 1920. Work thus proceeded from both ends to link Huarau and Portland via Waiotira, though this was not without dispute as local interests clamoured for alternate routes. There were debates over whether the line was to be a main line to Whangarei or to Kaitaia and the Far North, and when the line north of the Otamatea Bridge was initially authorised, it was envisaged to run via Waiotira and Kirikopuni as part of a main line to the Far North, with a branch from Waiotira to Whangarei. As it happened, government authorisation was first given for the "branch" from Waiotira to Whangarei; the "main line" via Kirikopuni was formally authorised in 1919 but never built and the branch to Whangarei became the main line. The PWD was able to offer a freight service between Huarau and Portland from 1923, but some parts of the line were only temporary due to difficulties with the terrain. The line was not formally handed over to the Railways Department until 29 November 1925 and the North Auckland Line was finally completed.
In the early days of the line, services were very localised and catered to local rather than national needs. When the line was completed, a through passenger express was established between Auckland and Opua. This was known as the Northland Express, and by the 1950s, it ran thrice weekly and took five hours and twenty minutes to run from Auckland to Whangarei. However, due to the twisting nature of the line, passenger services were inherently slow and they struggled to compete with private cars.
In November 1956, the Northland Express carriage train was replaced by a railcar service utilising 88 seaters. These popular services barely lasted longer than a decade, being withdrawn in July 1967 as the railcars proved mechanically unreliable. The Auckland Harbour Bridge had opened in 1959 and drastically cut road transport times north, and in the face of heightened competition, the railway could not compete and no dedicated passenger service replaced the railcars. Passenger carriages were now attached to some freight trains to create mixed services that ran between Whangarei and Auckland and from Whangarei to Okaihau and Opua; as they adhered to the freight schedules, the mixed trains ran much slower than the previous dedicated passenger services. This slow pace made them unpopular and the last mixed trains ran in 1976. Since this time, no passenger trains have run beyond the northern extremity of Auckland's suburban network with the exception of excursion trains a few times per year.
Commuter services between central Auckland and its western suburbs have been a mainstay of the North Auckland Line from its construction. Services between central Auckland and Swanson run on the Western Line; Waitakere, to the northwest of Swanson, was the terminus until July 2015, when diesel trains were replaced with electric and the Waitakere-Swanson section of track was not electrified. A bus shuttle service now runs between Swanson and Waitakere. Beyond Waitakere, services between Auckland and Helensville resumed in July 2008 on a trial basis, with a minimum of forty passengers daily required for the train to be permanently reinstated, but these services ceased on Christmas Eve 2009 due to that level of patronage not being met. If the Marsden Point Branch from Oakleigh is constructed, commuter services may also operate between Ruakaka and Whangarei. These would utilise the North Auckland Line between Whangarei and Oakleigh before running down the branch to Ruakaka.
Freight carriage in the North tended to suffer from thin settlement and heavy competition from New Zealand's coastal shipping. In one 1910 example, a fruit grower found it cheaper to ship canned fruit to Auckland by boat via Christchurch, rather than pay rail rates.
Freight service has typically been operated as two semi-independent sections; services between Auckland and Whangarei, and services north of Whangarei. Freight services currently operate twice every weekday each way between Auckland and Whangarei, with localised services shunting the line north of Whangarei - one service operates all the way to Otiria and two terminate in Kauri with a third if required. KiwiRail has announced that services north of Kauri will end in September 2016. Furthermore, south of Whangarei, a shunt operates each weekday to Portland, and a second if required to Wellsford; no freight trains at all operate on weekends except for one train between Auckland Whangarei (but only return if required). Between Whangarei and Waiotira, the line is also used by Dargaville Branch freight services, which run if required on weekdays.
In 2007, an upgrade of the North Auckland Line was described by Northland Regional Council chairman Mark Farnsworth as an important stage in the construction of the proposed Marsden Point Branch. The upgrade would increase tunnel clearances to enable large freight containers to be conveyed between Marsden Point and Auckland.
However, KiwiRail currently have the line under review as part of their turnaround plan. In 2011 KiwiRail asked the Northland Regional Council to pay for new wagons on the line.
When the railway around Whangarei was isolated from the national network, it was home to up to half of the members of the WB class. Diesel-electric locomotives has been used since 1966, when DB and DG class diesel-electric locomotives took over from the AB class and J class steam locomotives that had been working the line for the last couple of decades. In 1968, the Makarau tunnel was made larger to accommodate the DA class and they were the dominant motive power well into the 1980s. Although the DA class had been withdrawn from many other parts of the New Zealand network, the inability of the DC class to fit through the Makarau tunnel meant the DAs continued to operate until February 1989. By this time, the DF and DX classes were permitted to run to Whangarei, and nowadays, the DC class can also pass through the Makarau tunnel.