A proposed $5.5 billion Melbourne toll road might not actually ease truck and traffic congestion around the city, a top federal infrastructure bureaucrat says.
The Western Distributor will be built without federal help, and Department of Infrastructure and Regional Development secretary Mike Mrdak said that's because of concerns about whether it was a long-term solution.
"We are concerned with some aspects of the project, including the ability of it to deal with much of the demand through that East-West corridor in Melbourne," Mr Mrdak told a Senate estimates hearing in Canberra on Monday.
"(And) whether this really is a long-term solution to the issues coming out of both port traffic but also the East-West traffic out of the CBD."
Toll road provider Transurban told Labor about its Western Distributor plan before the 2014 election, but it was kept secret until shortly afterwards, before winning full government support in 2016.
"We're building Melbourne's long overdue second river crossing - a true alternative to the West Gate Bridge that will slash congestion so Victorians can spend less time stuck in traffic on the M1," Premier Daniel Andrews said when the project was confirmed in June.
Victoria spent $1.2 billion to dump stage one of the controversial East West Link freeway connector, and the Western Distributor was hailed as the road the city needed more.
Opposition leader Matthew Guy said the federal department's comments showed it was the wrong project to build.
"It's hard to believe the state is spending so much money on a road project that no one seems to think is the solution to Melbourne's congestion," Mr Guy told reporters.
Infrastructure Victoria - set up to "take the politics out of infrastructure" - was explicitly told it could not assess whether the Western Distributor was a good project for the state.