Auckland railway electrification

All four suburban lines between Swanson in the west and Papakura in the south are electrified at 25 kV 50 Hz AC,[12] the same voltage as the North Island Main Trunk between Te Rapa and Palmerston North. In contrast, the Wellington suburban network (electrified 1938–55) uses 1,500 V DC.

About 3,500 masts were installed as part of the project.[13] The Onehunga Line was the first line to be commissioned.[14]

The system is supplied by two connections to Transpower's 220 kV national grid, one at the former Southdown Power Station and the other at Transpower's Penrose substation. Both connections are duplicated (Penrose has limited duplication due to having only one 220/25 kV transformer), and one connection can supply the entire network if the other one fails, creating a high level of redundancy. KiwiRail said electrification would use less than 1% of Auckland's electricity capacity.[3]

In conjunction with the electrification to Pukekohe, a third connection for the system is planned, supplied from Transpower's Drury substation.[15]

The decision to electrify was partly prompted by the ageing diesel train fleet becoming unreliable.[16] The fleet comprised diesel multiple units (DMUs) bought second-hand from Perth, Australia, and rebuilt British Rail Mark II carriages in push/pull configuration with DC and DFT locomotives; the Auckland Regional Transport Authority established that electric trains would be cheaper to run long term. Around the world, cities with high-frequency metropolitan passenger rail services use electric trains, partly because of their quieter operation, faster travel between stations and greater environmental benefits.[12]

After electrification a small number of diesel trains were retained to provide shuttle services between Papakura and Pukekohe.[17] In May 2012, the possibility of extending electrification to Pukekohe was to be investigated by Auckland Transport.[18]

The EMUs were delivered from 2013, with the last units in 2016.[14] In June 2013, it was confirmed they would be classified AM class (standing for Auckland Metro), with the motor car classified AMA, trailer car AMT, and motor/pantograph car AMP.[19]

In July 2017, Auckland Council's Finance & Performance Committee approved in principle an order from CAF of 17 EMUs equipped with batteries (BEMU) that would extend electric unit services to Pukekohe. The approval was subject to the New Zealand Transport Agency agreeing to fund at least 50% of the cost of the order and the future operation; the new units were expected to start operating in 2019.[6] In November 2017, it was announced that the proposed BEMU order had been cancelled and another 15 AM class units would be ordered.[7] The rationale for this became clear in late April 2018 when electrification between Papakura and Pukekohe was announced as part of the $28 billion Auckland Transport Alignment Project.[8][9]

There were 31 public level crossings between Swanson and Pukekohe and 8 on the Onehunga Branch. With electrification there is a need to safeguard crossings, since electric trains are quieter and more frequent. This includes bridges or tunnels in some cases, and the closure of small suburban street crossings in others.[20] Height restrictions of 4.25 metres or 5.0 metres were imposed to keep vehicles clear of overhead wires.[21]

The Broadway overbridge in Newmarket and Parnell Tunnel were among the first of about 40 structures that needed modification before electric trains could run.[22][23] Tracks were lowered in Purewa Tunnel on the Eastern Line.[24]

The electrification was completed in conjunction with a NZ$90 million upgrade to the signalling system.[13] As the AC return current is through the rails, insulated rail joints had to be removed (or circumvented by joining rails with a bond wire). The old signalling system used track circuits with insulated rail joints; these had to be installed initially for the duplication of the Western Line. The new European Train Control System (ETCS, Mark II) uses train detection by axle counters.[25]

The planning of the Parnell station[26] and upgrades to existing stations at Ellerslie (in combination with motorway works), Onehunga (lengthening for 3-car units) and Mount Albert (amenity upgrades),[14] took into consideration the electrification of the network, so that modifications were not needed later.

Funding arrangements for the rolling stock purchase included the construction of a maintenance depot and stabling facilities.[27] After looking at potential sites, 4.4 hectares of the old Winstone Quarry in Wiri (next to the South-Western Expressway, near the closed Wiri Station, and bordered by Roscommon and Wiri Station Roads) was selected, being large enough to house all the facilities required and adjacent to the NIMT railway line.[28]

Significant earthworks to prepare the site commenced in January 2011 and in May 2012 a NZ$40 million contract to construct the facility was awarded to Downer New Zealand Limited.[29] The facility was officially opened on 5 July 2013[30] and joint operational control was handed over to the train operator Transdev Auckland Limited and train supplier & maintenance operator CAF on 28 August 2013. The cost of the depot including land, construction and facility equipment was approximately NZ$100 million.

The facility includes 6 kilometres of sidings and a 7,650 square metre depot building consisting of office facilities and the main workshop where servicing of the 57 electric trains takes place. The workshop has seven maintenance berths and has overhead gantry cranes and jacking systems for lifting the trains, high-level platforms to access train roofs, under-floor pits and a wheel lathe. There are an automatic train wash and covered platforms to facilitate cleaning of the inside of the trains.[28] The facility has been future proofed to maintain a fleet of up to 109 electric trains.[31]

The ground floor offices house CAF and the first floor Transdev and staff amenities. The Transdev offices include the depot control office and driver training facilities, which include two train simulators. Each simulator is laid out exactly like the driver's cab with a large flat screen display in place of the windscreen that displays the view that the driver would see from the cab. The display is programmed with the Auckland railway network, filmed in 2012 and converted into video graphics. The simulator can be set to simulate daytime or night-time and includes a range of weather conditions, and it can simulate faults in the train and emergency situations.[32]

Train movements within the facility are controlled by Transdev staff from the depot control office.

The stabling capacity is 28 electric trains. There are other stabling yards at Henderson, The Strand Station, and Papakura.

During the summer 2011-2012 shutdown, the approaches to Britomart were rebuilt to allow for electrification, masts installed and holes bored, and wiring completed in some areas.[40] During the 2013-2014 shut-down, the complex job of wiring Quay Park Junction, The Strand stabling facility and Britomart was completed.[41] By January 2014 wires had been installed:

• Western Line: Swanson-Mount Albert, Newmarket-Britomart;
• Southern Line: Britomart-Papakura;
• Eastern Line: Britomart-Purewa Tunnel south end;
• Manukau Branch;
• Onehunga Branch.[41]

Services were planned to start during April 2014[42] and the first scheduled electric train service (from Britomart to Onehunga) took place on 28 April 2014.

The project was completed on 20 July 2015 with full electric train service across the network.[43]

The section of the Southern Line between Pukekohe and Papakura, which is a shuttle service operated by ADL/ADC class diesel multiple units. The Draft future urban land supply strategy states that electrification of the network would be extended southwards to Pukekohe once the special housing area at Paerata is opened up in the "second decade" of the plan, that is by 2030.[45] A petition for the electrification to be undertaken sooner was started by a local resident of Pukekohe,[46] and the matter was discussed by both main parties during campaigning for the 2017 general election. In preparation for future electrification, KiwiRail has been consulting with Transpower about a third power supply for its network from the Drury 220 kV switching station.[47]

In 2020, the government announced $371 million in funding to extend electrification from Papakura to Pukekohe,[48][49] with the upgrade expected to take two to three years (see also New Zealand Upgrade Programme).[50][51] There has been criticism that KiwiRail is negotiating with two overseas-owned companies (McConnell Dowell, South Africa and John Holland, China) to carry out the contract, which is expected to provide over 200 jobs.[52] This work is to commence in 2020.[53]

The section of the Western Line between Swanson and Waitakere. Electrification was not carried out due to the low roof height of the Waitakere Tunnel and because enlarging it was considered an to be an unjustified expense considering the low passenger numbers to Waitakere Station. Rail services to Waitakere were withdrawn when electric services commenced on the rest of the Western Line. Waitakere Village is now served by bus services connecting to Swanson and Henderson.