Vic could go alone on new toll road

Victoria is "absolutely" serious about building the $5.5 billion Western Distributor alone if negotiations with a private toll company break down.

The likely final route for the project will be known in March, with environmental consultation due to start in February.

Toll company Transurban proposed the Western Distributor, which would see tolls extended on existing private roads for another decade.

But Treasurer Tim Pallas said the government was prepared to build the road without doing a deal on tolls with Transurban.

"Absolutely it's a serious option," he told reporters on Tuesday.

"They have been prepared to make hard decisions as we've negotiated, insisted upon extracting value for Victorian taxpayers in this process.

"But one thing that we have been very, very keen to ensure is that this is seen as a genuine partnership."

Mr Pallas said negotiations were continuing with the federal government over its share of funding for the new road.

An environment effects statement will be required for the Western Distributor, taking in the widening of the West Gate Freeway, a tunnel under Yarraville, a second river crossing of the Maribyrnong and an elevated road along Footscray Rd.

Mr Pallas said community consultation would start with the most likely route, but the final route would be confirmed after that process.

Opposition spokesman John Pesutto said the final route was key.

"I think it's very hard for Victorians to accept that you can have a final and formal environmental impacts process when you don't know the final route," he told reporters.

Mr Pesutto also said the government had not been transparent enough with the business case to know if the state could build the road without Transurban.