That's the claim of Keira MP Ryan Park, who felt the project - which is at the detailed design stage - isn't moving forward due to a lack for funds.

The beleaguered Sydney Metro has seen its budget blowout by $4.3 billion.

"We could have had this project fully funded just from cost blowouts on these projects that the government has mismanaged," Mr Park said.

"The Mt Ousley Road Interchange is a vital piece of infrastructure and it is time this government committed funds to the project.

READ MORE: Lawrence Hargrave Drive closes for eight weeks

"The budget is coming up in June and the community certainly expects to see funds allocated to the next stage of this project."

The interchange would provide grade separation for cars and heavy vehicles, a bridge over the motorway and a new northern entrance to the University of Wollongong.

A Transport for NSW spokesman declined to say whether $4.3 billion would be enough to complete the project.

He said $3 million had been allocated towards the project in last year's budget.

"The project has achieved planning approval and the next stage will be to prepare the detailed design for the project," the spokesman said.

"Timing and funding for construction of the interchange upgrade is still to be confirmed."

He also said Transport for NSW had continued to improve the design of the proposed interchange.