Victoria's Suburban Rail Loop was conceived by a single executive and handled by private consultants under a veil of secrecy over the mammoth rail project, a report says.
Victorian Ombudsman Deborah Glass tabled her report on the alleged politicisation of the state's public sector, which highlighted culture of secrecy where the public sector was marginalised.
It took aim at the early planning phase of the Suburban Rail Loop and how it was devised by a one senior executive, developed by consultants and kept secret from expert public servants working in transport departments.
The executive behind the idea was "headhunted" to join the newly created Places Victoria department in a corporate strategy role without the position being publicly advertised.
The executive, who previously worked as a senior ministerial staffer, revealed the Suburban Rail Loop idea was firmed up after they attended an infrastructure conference held by a consultancy firm.
The firm was eventually hired, without others being considered, to develop the project due to its "niche" experience.
People working in the secret select group were threatened with court action through "confidentiality deeds" if any information about the project was divulged before it was officially announced.
The project was officially announced three months before the 2018 state election.
This was to prevent speculators buying land along the proposed route, witnesses said.
Government bodies and senior public servants were excluded from briefings on the 90km orbital rail line.
The rail loop's early creation was inconsistent with the traditional way of how projects are developed and became politicised once it was taken to an election without independent scrutiny.
"It was subject to excessive secrecy and 'proved up' by consultants rather than developed by public servants," Ms Glass said.
"Its announcement 'blindsided' the agency set up by the same government to remove short-term politics from infrastructure planning."
She observed a sense of "betrayal" among the public service, as others wondered how and why it was conceived.
"The lack of rigorous public sector scrutiny over such projects before they are announced poses obvious risks to public funds."
Treasurer Tim Pallas denied public servants were sidelined and defended the use of consultants.
"(Public servants) produce some really good policy ideas but they should never be the sole source of good ideas," he said on Wednesday.
Victoria's independent infrastructure agency did not recommend a suburban rail loop in the state's first 30-year infrastructure strategy in 2016.
