The Senate has given the Federal Government until 5pm (AEST) today to release traffic modelling and cost benefits information relating to the $1.6 billion Perth Freight Link highway.

The modelling documents, any Barnett Government business cases submitted, and the Infrastructure Australia Board evaluation of the project could come to light before the end of Tuesday.

There is strong opposition to the proposed freight highway, with residents and local governments expressing outrage ever since the plan was allocated $925 million in Commonwealth funding last year.

The motion to release the documents was moved by WA Greens Senator Scott Ludlam, who said the Government needed to justify why taxpayers needed to pay for the road.

He says he only way to get the public onside is to release the documents.

“This is a major freight freeway project that's proposed to push through a wetland and through suburban neighbourhoods, and the Government has never released the business case,” Mr Ludlam said.

“There's no traffic modelling, there's no benefit cost analysis and there's no Infrastructure Australia assessment.

“That should be in the public domain before this funding decision goes ahead.”

Mr Ludlam syas it is likely that papers will show the road is unnecessary.

“You hear from people who worked close up to the project, from the Government side, from the corporate side, who have actually seen these things and they'll tell you that the numbers don't stack up,” he said.

“I think if it was a good news story then that material would be in the public domain, but I suspect and fear that when that material finally does make its way into the public domain, it's going to show that the project will be a disaster.”

The Senate is expected to pursue further action if the documents are not revealed today.

“I've got some ideas on that, but that will be up to what the Senate decides,” Mr Ludlam said.