The South City Line (S-C) is a train service operating in Auckland, New Zealand. The line runs between Pukekohe and Newmarket via Grafton. It connects to other rapid transit lines: AirportLink Bus, NX1, NX2, East West Line (E-W), Onehunga West Line (O-W) and WX1. Prior to the opening of the City Rail Link on 13 September 2026, services ran direct to Waitematā from Newmarket via Parnell as the Southern Line. The South City Line runs every 10 minutes during peak times and every 15 minutes during off-peak.
Prior to the opening of the City Rail Link, Southern Line services used the Newmarket Line from Waitematā to Newmarket, then followed the North Auckland Line to Westfield Junction, and thence onto the North Island Main Trunk (NIMT) line as far as Pukekohe. In its entirety, this line followed the original 1875 North Island Main Trunk route between central Auckland and Pukekohe.
The line, originally single-tracked, was duplicated, piecemeal, between 1909 and 1939. In 1915, the original single-track Parnell tunnel was bypassed by a twin-track tunnel. The older tunnel can be seen alongside the current one, between Parnell station and Newmarket Junction.
History
In 1930, the Westfield Deviation opened a new eastern route for the NIMT between Auckland and Westfield via Glen Innes. The route between Auckland and Westfield via Newmarket then ceased to be part of the NIMT. The portion between Newmarket and Westfield became part of the North Auckland Line (NAL), which runs between Westfield and Whangārei.
The Southern Line suburban services continued to run on the older route. A new line, called the Eastern Line, was introduced for services on the new route. While the Eastern and Southern lines have a different route between Auckland and Westfield, they share the same tracks between Westfield and Puhinui station.
Third Main Line
Construction for the third main line, as part of the Wiri to Quay Park began in 2020 and was completed by 2025. It is expected to ease congestion on Auckland rail lines by allowing "through" trains to pass stationary trains at stations, improve rail freight access from the Port of Auckland to the Westfield yards and allow more frequent passenger and freight services. The new line runs between Westfield Junction and just south of Wiri Depot.
Along with the rest of Auckland's suburban railway network, the Southern Line was electrified from Waitematā to Papakura, with electric services beginning in 2014. Services between Pukekohe and Papakura were initially provided by diesel multiple units (DMUs). In 2020, as part of the New Zealand Upgrade Programme, the government announced $371 million in funding to extend electrification from Papakura to Pukekohe. The project was completed in early 2025, and electric train services from Pukekohe commenced on 3 February 2025.
Replacement
After the opening of the City Rail Link on 13 September 2026, the Southern Line became the South City Line; trains now run Pukekohe to Newmarket, then to Waitematā railway station via Grafton and the City Rail Link before returning to Newmarket via Parnell and terminating.
Ngākōroa Station is under construction and due to open in 2027. The station will be located on the existing rail line between Paerātā and Drury, about 450 m south of the existing intersection of State Highway 22/Karaka Road and Jesmond Road.
