Nearly 90 per cent of workers and materials used during the design and construction of Victoria's Western Distributor road project must be from Australia, the State Government says.

The $5.5 billion project is expected to create 5,600 jobs during construction.

The successful builder will also have to make sure local workers and materials are used for at least 82 per cent of the work installing and operating the electronic toll collection points.

And at least 10 per cent of total hours spent on the project must be worked by apprentices, cadets and trainees.

The Andrews Government announced the project to divert trucks from the West Gate Bridge, after axing the former Coalition government's East West Link.

Roads Minister Luke Donnellan said the local content requirements would support Victorian jobs, and rejected suggestions it would push up the cost to taxpayers.

"Any tender that we put out there has got to be value for money, to ensure we're getting the best value for money for the Victorian public," he said.

"So that rides over the top of all these."

Project must use local steel, Government says

The State Government will also require companies that tender for the project to "maximise" the use of local steel.

Roads Minister Luke Donnellan says local content requirements will support jobs. ( ABC News: Stephanie Anderson )

"There is no specific one figure for that," Mr Donnellan said.

"But to meet the 89 per cent locally supplied product and services... it would have to be pretty high."

The specification of "local steel" allows for the use of steel from anywhere around Australia.

But Mr Donnellan said it would probably come from Victoria.

"It can be Australian, but when you look at where many of the steel producers are in terms of milled steel, it's in Victoria," he said.

AWU welcomes boost to jobs

The Australian Workers Union (AWU) said the announcement would create thousands of construction jobs.

AWU Victorian secretary, Ben Davis, said it provided strong support for the local steel industry.

"I'm heartened by the mandate that's come out to maximise the use of local steel," he said.

"It's good to finally see, after a very lean period, a number of construction and infrastructure projects being announced.

"In contrast to their predecessors, an 89 per cent local content provision is a lot higher than what we're used to seeing, and it means more local jobs."

But the Victorian Opposition said the announcement showed the Government was wrong not to proceed with the East West Link road project.

Opposition Treasury spokesman Michael O'Brien said they had introduced a requirement for at least 98 per cent local steel to be used.

"Daniel Andrews can't even deliver that on his Western Distributor," he said.

"It's not a good outcome on jobs, and it's certainly a worse project than the one he scrapped."