The company spearheading the construction of Melbourne’s West Gate Tunnel says the project is now expected to be completed one year later than planned.

The $6.7 billion tunnel, which will be an alternative to the city’s heavily congested West Gate Bridge, was meant to be finished in 2022.

But, in a briefing to investors on Monday, tollroad giant Transurban said 2023 was now the expected end date and that tunnelling works can’t start until there is “resolution on a range of matters”.

That includes confirmation of the disposal site for contaminated waste, preparatory works, gaining relevant approvals and resolving commercial matters.

Transurban said it’s committed to working with the Victorian government and its building subcontractors to “resolve the tunnelling issues”.

The West Gate Tunnel is now expected to be complete in 2023. Photo: AAP

“Proposed disposal sites are working through requirements to gain necessary planning and environmental approvals,” it said in a slide presentation to investors.

“Progress continues on-site with over 15 million working hours on the project.”

Joint-venture builders CPB Contractors and John Holland earlier told Transurban they didn’t believe the project could be completed by 2022.

Transurban had said in February it believed a 2022 finish was possible.

The state government said it expected its contract to be honoured.

Victorian Minister for Public Transport and Infrastructure Jacinta Allan (centre) tours the West Gate Tunnel construction site. Photo: AAP

Transport Minister Jacinta Allan said Transurban stood to lose millions by not honouring the contract’s initial deadline, particularly from lost toll revenue.

“Every day that this project is not completed beyond 2022, Transurban lose millions of dollars,” Ms Allan told reporters.

The minister also said that while coronavirus had put additional strain on the project, the conflict between Transurban and contractors needed to be resolved quickly.

“We’ve got to get on.

“Resolve those disputes with CPB and John Holland, resolve the disposal of the soil from tunnel boring activities, get those tunnel boring machines going as quickly as possible and honour the commitment and the contract,” Ms Allan said.