With Evan Tattersall behind him, Premier Daniel Andrews announces the rail line on Tuesday morning. Credit:Joe Armao Speaking to The Age on Tuesday, Mr Tatersall said major tunnels had been completed “all over the world”, and Melbourne should be no different to other major metropolises as it reached a population of 5 million. “If you look around – at Paris, at Singapore, New York – ring-road style railway lines are done everywhere, through all sorts of challenging ground conditions,” Mr Tattersall said. “There is nothing new about working through the line proposed here.”

Mr Tattersall said the Metro Tunnel project he was responsible for had seen “a lot of preparation, and a lot of geotechnical work”, before construction commenced. One engineer pointed to sewers built decades ago in the south-east to show a rail tunnel stretching for many kilometres would, in a construction sense, be straightforward. The Dandenong Trunk Sewer is one of Melbourne’s main routes for wastewater from the north-eastern suburbs, funnelling it to the Eastern Treatment Plant in Bangholme in the south-east. “It was done back in the 1970s by the Melbourne Metropolitan Board of Works,” said Chris Coulson, director of ground engineering at global consulting firm AECOM. Inspecting work on the Dandenong Trunk Sewer in 1976.

This tunnel was “big enough to walk through”, he said, and digging rail tunnels beneath the middle suburbs of Melbourne would be easily achievable once a route was decided. “Tunnelling in that part of Melbourne is nothing new; ground conditions aren’t unknown,” he said. Loading While Melbourne’s geology meant the project wasn’t simple – from sandy soil in the south through rock in the north-east – all were traversible, he said. “Topographically you are staying away from the Dandenongs,” Mr Coulson said, meaning there were no significant hills to tunnel through.

AECOM previously worked on the Baillieu government’s analysis of a rail line to Doncaster, and Mr Coulson said it would have been relatively straightforward to build through that part of Melbourne. “With rail you are constrained to quite low grades, and there hasn’t been a significant reason you can’t put rail through the [alignment released on Tuesday],” he said. While it emerged on Tuesday that the government’s project advisor, Infrastructure Victoria, was never asked about the project, an earlier piece of work by the agency showed how long mega-projects like it can take. Its 2016 Learning from the past report found the City Loop was first proposed in 1929 and started in 1971. The Metropolitan Ring Road was first pitched in 1954 and started in 1989. And CityLink was also first floated in 1969, and began construction in 1996.

This makes the four-year plan Mr Andrews promised on Tuesday somewhat optimistic. One well-connected transport figure who attended a CBD briefing for stakeholders from the premier yesterday had a darker view of the promised rail tunnel. They said the planning for the rail line in the office of Development Victoria – instead of in one of the state’s many transport agencies capable of assessing the idea – showed the project’s highly political aim. Loading Replay Replay video Play video Play video And it meant other projects, such as a proposed “Melbourne Metro 2” rail tunnel to run under central Melbourne, would now be put off for many years.

“It’s too hard to talk about reality. Instead, let’s talk about something that is so wonderful and so far out there that no-one can grab onto it,” they said.