The Northern Line (numbered T9, coloured red) is a commuter rail line operated by Sydney Trains in Sydney, New South Wales, Australia. It serves some of Sydney's Inner West and Northern suburbs. It was spun off from the old T1 North Shore, Northern & Western Line as a separate line in April 2019, to distinguish and make it more easily identified from the other T1 services. It is also a reincarnation of the older Northern Line which was under operation until 2013. History Original incarnation (until 2013) The traditional Northern Line was the suburban portion of the Main North railway line (Strathfield - Hornsby) which opened in 1886 and was electrified in 1926. When the Sydney Harbour Bridge was opened, it connected railway services from the Main North line and the City underground onto the North Shore line. Passenger services used to operate as the Main North Line (same name as the physical railway line) and was colour coded red on railway maps. It operated all the way to Cowan, until the service was truncated to Berowra in January 1992. The service, along with the North Shore Line service (yellow), later also ran along the North Shore railway line towards the City via the Harbour Bridge, forming a continuous loop via Strathfield, Epping and back to Hornsby. In later years, the line operated as the Northern Line and ran from Hornsby to North Sydney via Strathfield and the City, with the North Shore line replacing services between Hornsby and Berowra. In February 2009, the Epping to Chatswood rail link was opened. In October 2009, the Northern Line service was integrated with the shuttle service between Epping and Chatswood. As a result, the traditional Northern Line was split in two, with trains from north of Epping operating via the new link, approaching the city via the North Shore Line and rejoining the traditional route before terminating at Epping. Part of T1 (2013 to 2019) In October 2013, the Northern Line, North Shore Line and Western line were merged to form the T1 North Shore, Northern & Western Line, which was colour coded yellow. On weekdays, trains from the upper Northern Line (Hornsby via Macquarie University) joined up with the Western Line trains towards Richmond or Emu Plains, while trains from the lower Northern Line (Epping via Strathfield) joined up with the North Shore Line trains towards Hornsby or Berowra. On weekends,