The Australian Greens have noted the long-anticipated release of Infrastructure Australia's sketchy assessment of the Perth Freight Link project.

"We can understand now why the Barnett Government is so reluctant to release information about the Freight Link. Every time someone does, it damages the case," Senator Scott Ludlam said today.

"The assessment reveals that the Barnett government did not bother to compare the Freight Link with the costs and benefits of developing a dedicated road and rail link to the Outer Harbour in Cockburn Sound.

The Senate has ordered the Federal Government to produce key documents relating to the Perth Freight Link, supporting a Greens' motion moved by Senator Scott Ludlam this afternoon.

"The WA and federal government have committed more than $1.6 billion of taxpayers' money to an unplanned, maligned and destructive freight freeway that will disfigure suburbs across Perth's southern suburbs, and they've done so without producing any meaningful reports or data to justify their position," Senator Scott Ludlam said today.

The Australian Greens have slammed the WA Government for environmentally approving the Beeliar Wetlands section of the Roe 8 freight highway, pointing out that no amount of so-called protection could safe-guard against slamming a multi-lane freight freeway through such a unique and significant area.

"This is an appalling decision from a government that doesn't even to pretend to care about the damage to people, suburbs and the environment," Senator Scott Ludlam said today.

The Australian Greens said today that a damning report on the Perth Freight link should be the final nail in the coffin of the unwanted project.

The report was prepared by Professor Peter Newman and Cole Hendrigan from the Curtin University Sustainability Policy Institute (CUSP) and describes the project as ‘a waste of taxpayers' money', confirming what residents and rail transport advocates have been saying for years.