A $3.6 billion contract has been awarded on what is expected to be one of Melbourne’s biggest rail projects for several decades as the project moves closer to construction.

On Tuesday, the Victorian Government announced that a consortium of global tunnelling experts has been awarded the contract to build 16 kilometres of twin tunnels between Cheltenham and Glen Waverley as part of the Suburban Rail Loop East project.

Tunnelling is now set to begin in 2026.

The consortium includes CPB Contractors, Ghella and Acciona Construction.

The two other unsuccessful bidders for the Cheltenham to Glen Waverley Package will now compete for the second tunnelling package from Glen Waverley to Box Hill, which is set to be awarded in 2024.

Set to open in 2035, SRL East will link the middle suburbs from Cheltenham in Melbourne’s south-east to Box Hill in the east via two 26-kilometre tunnels.

It represents the first project as part of a proposed 90-kilometre Suburban Rail Loop project that will link Melbourne’s middle suburbs from Cheltenham in the south-east to Werribee in the south-west.

Tunnelling for the project will be completed using custom-built tunnel boring machines (TBMs).

The TBMs will be launched from train stabling facilities at Heatherton, Monash and Burwood.

On average, the tunnels will be 26 m deep – about six storeys below ground. At their deepest point, the tunnels will reach 60m below ground.

All up, SRL East is expected to generate around 8,000 direct construction jobs.

At least 12 percent of all hours will be worked by trainees, apprentices and cadets.

Work is currently underway in Burwood to construct the TBM launch site.

Still, as noted in The Guardian, the project has been subject to controversy.

In a scathing report on the politicisation of the public service last week, Victorian Ombudsman Deborah Glass said the project was subject to excessive secrecy and was proved up by consultants rather than public servants.

Glass noted that Infrastructure Victoria did not recommend the project and was not consulted before the project was announced.

Meanwhile, the Victorian Auditor General has concluded that the business case released last year was not sufficiently comprehensive, robust or transparent and did not support fully informed investment decisions.

Meanwhile, there is uncertainty about how the project will be funded.

All up, SRL East is expected to cost $30.0 billion to $34.5 billion.

Thus far, however only, $14 billion of the funds have been committed. This consists of $11.8 billion from the Victorian Government and $2.2 billion from the Commonwealth Government.

Exactly where the remainder of the funds will come from remains unclear.

Thus far, the government has said only that the project will be funded by contributions from the State and Commonwealth Governments and a mix of value capture opportunities – the precise nature of which remains unclear at this stage.

Victorian Premier Jacinta Allen welcomed the contract’s signing.

“We are full steam ahead with the Suburban Rail Loop – by 2026, tunnel boring machines will be in the ground and Victorians will be hard at work delivering a project that will slash travel times and transform our transport system,” Allen said.