[1] Operated by Metro Trains Melbourne, it is the city's fifth-shortest metropolitan railway line at 20.1 kilometres (12.5 mi).

[2] The continued existence of the line was in serious doubt in the late 1980s and early 1990s, with proposals for it either to be converted to a light rail or fully closed.

They included replacing sleepers, upgrading signalling technology, removing level crossings, introducing new rolling stock, and improving station accessibility.

[12] In March 1928, despite strong resistance from the Railways Commissioners, the state government ordered the reopening of the section from Fawkner to Somerton for passengers.

[13][14] Passenger services were provided by an AEC railmotor, which connected with electric trains at Fawkner.

At the outer end of the railway line, a bus service was provided, connecting with trams in North Coburg.

Automatic signalling advanced a little further along the line in August 1971, with Royal Park to Jewell being converted.

[2][3][4] A report submitted to the Cain government determined that the route suffered from low passenger numbers, redundancy with the Route 19 tram, outdated signalling systems, manned boom gates well past their prime, and that substantial investments would be required to modernise the line to meet modern standards.

[18] After discussions with local councils, unions, the public, and the Metropolitan Transit Authority, two options were floated.

These options included:[19] These proposals were put to rest in April 1995, when it was announced that $23 million would be spent upgrading the line.

[19][4] The work included the provision of power signalling for the whole line, and the installation of boomgates at all level crossings, except for a few that were closed instead.

[19] At the time, many of the numerous level crossings on the line were still controlled by gatekeepers, who opened and closed the gates manually for every train.

[27][28] The decision to build two stations in different locations instead of rebuilding all 3 generated significant criticism from residents and the local council.

Local newspaper Brunswick Voice reported that the Minister for Transport Infrastructure, Danny Pearson, claimed "the decision to build two stations followed 18 months of technical and engineering assessments which found fewer stations would boost capacity on the line in the future and deliver more open space", noting that "[the government claimed] the plan would also minimise the impact to heritage in the area, but [the politician] provided no detail about whether the three station buildings and the historic boom gate operators' cabins would be preserved".

[32] Train services on the Upfield line are also subjected to maintenance and renewal works, usually on selected Fridays and Saturdays.

The route is 20.1 kilometres (12.5 mi) long, making it the fifth shortest line on the Melbourne metropolitan network.

[46] The Upfield line uses two different types of electric multiple unit (EMU) trains that are operated in a split six-car configuration.

The rarer rolling stock featured on the line is the Comeng EMUs, built by Commonwealth Engineering between 1981 and 1988.

[48] These train sets are the oldest on the Melbourne rail network and subsequently are planned to be replaced by 2026.

The new trains will feature:[55] In compliance with the Disability Discrimination Act of 1992, all stations that are new-built or rebuilt are fully accessible and comply with these guidelines.