[8][9] Although the Victorian government signed the first $3.6 billion contract with the Suburban Connect consortium in December 2023 to build the tunnels,[10] the state Liberal/National opposition remains opposed to the system.

[11] The Melbourne transport network was substantially developed in the late 19th century, when the newly available technology of the railway enabled population growth away from the city centre.

Furthermore, a program of freeway construction in the wake of the 1969 Melbourne Transportation Plan reinforced the structure of the suburbs and introduced car dependence to new regions of development not served by the legacy rail network.

As a consequence, Melbourne, unlike many cities of comparable size, did not develop any major centres of employment or dense population in its outlying regions over the course of the 20th century.

[12] A number of orbital lines were constructed at the peak of railway development, but most failed to attract the necessary traffic of passengers and goods to remain sustainable into the late 20th century.

[15][a] EastLink, a similar orbital freeway through the eastern suburbs, opened in 2008,[17] but was less successful, failing to reduce traffic meaningfully on parallel arterials such as Springvale Road.

[20] From 2002, the SmartBus program introduced three orbital bus routes in an attempt to meet the city's burgeoning need for outer suburban public transport.

[21] In August 2018, three months prior to the 2018 Victorian state election, then Premier Daniel Andrews promised that a re-elected Labor government would undertake "the biggest public transport building program in Australian history", in a speech to the Committee for Economic Development of Australia.

[30] Rail Projects Victoria announced registrations of interest for potential contractors were open in June,[31] and the first geotechnical investigations began in July in Box Hill.

[32] The state government announced the formation of a Suburban Rail Loop Authority in September, at the same time as confirming station precincts for SRL East.

The government stated that it expected $30 to $34.5 billion would be spent on the project over the 14 years to the opening of the first stage in 2035, with significant works on SRL North taking place as part of that expenditure.

The first stage will connect Melbourne's eastern and south-eastern suburbs, including twin 26 km (16 mi) underground tunnels from Cheltenham to Box Hill via Monash University.

The SRL Strategic Assessment produced by Development Victoria in 2018 identified four distinct sections of the route, some of which are formed by other projects or existing rail corridors.

[48][50] Apart from the termini at Sunshine and Werribee, the Strategic Assessment did not identify specific routes, intermediate stations or connections to other lines for SRL West, and suggested it would be the final section constructed.

[23] He announced federal Labor's official support in mid-October 2018, committing $300 million in business case funding and saying the project responded to an "old map of Melbourne... [that] simply doesn't work any more".

[23] Despite the Coalition opposing the SRL, the plan was embraced by influential former Liberal premier Jeff Kennett, who called for bipartisan support for the project immediately after it was announced, despite expressing doubts about the accuracy of the $50 billion costing.

[61][62] After the Labor government won a third term at the election with an increased majority, then Premier Daniel Andrews said the result was the second clear endorsement of the project by Victorian voters.

[65] The Age, in its editorial the day following the announcement, wrote that "there are so many reasons to endorse this proposal that it’s easy to get carried away", but observed that "good government is ultimately about more than just vision.

It’s about having the inventiveness, discipline and fiscal capacity to make that vision reality", and suggested that the true test for the SRL would be the government's ability to complete it.

[68] The SRL was warmly received by the Public Transport Users Association, with spokesman Daniel Bowen describing it as "Big City thinking" in an opinion piece.

[70][73] An impromptu competition organised by The Age to redesign the Melbourne rail network map to incorporate the SRL received entries from leading cartographers and attracted thousands of public votes in the days after the announcement.

[74] Both the plausibility and practicality of the government's initial headline $50 billion construction cost for the project were the subject of significant commentary at the time of the SRL's original announcement.

[70] Prominent transport commentator Daniel Bowen, in a "back of the envelope" analysis, concluded that the government was "close to the mark" but expressed reservations about the accuracy of his estimate.

[78] In 2022, Victoria's Parliamentary Budget Office (PBO) released analysis finding that the total construction and operating costs of SRL East and North together between 2022 and 2085 in 2022 dollars would be $29.214 billion, significantly less than other public estimates.

[82] Minister Jacinta Allan dismissed the report, saying the Opposition framed the PBO request in order to obtain a large number, including unadjusted asset renewal expenses over fifty years.

[87] Independent analysis of the plan by SGS Economics in the weeks following its release broadly supported the Strategic Assessment, noting that if the SRL had been in operation in 2018, a 2 km (1.2 mi) catchment around each station would have captured "roughly: 270,600 jobs, 416,100 residents, 212,300 workers, and 112,600 higher education students".

It argued that SRL East, consequently, would have served 30,000–50,000 daily trips if in operation in 2018, with the qualification that the level of service provided would need to make travel time competitive with car journeys.

However, it concluded that the benefits and potential patronage of the North-East and two western sections were more nebulous, as their impact would depend on the efficiency with which the project was leveraged to create new development.

[90][91] The Age published an article criticising the SRL being devised by only a few of Daniel Andrews’ trusted insiders rather than through regular government agencies or the bureaucracy.