The order to release 75 documents about the $2 billion Perth Freight Link would reveal that the biggest road infrastructure project in WA's history was politically motivated with little planning, says former federal Labor MP and state minister Alannah MacTiernan.

Ms MacTiernan won a two-year battle when the WA and federal governments were ordered this week by the Administrative Appeals Tribunal to grant her Freedom of Information request for documents related to the controversial $2 billion Perth Freight Link.

The federal infrastructure and state main roads departments had fought in court for two years to stop the release of information about the heavy haulage route, arguing the documents were too sensitive and would compromise negotiations.

The federal infrastructure and state main roads departments can appeal the decision, which they are considering.

The project, which is majority federal funded, aims to provide a better link between Fremantle Port and Perth’s heartland industrial areas for trucks and be part of a free flowing 85km route that goes north to Muchea.

It has been a divisive issue, with opposition for a number of reasons: it will cut through the Beeliar Wetlands and the environmental approvals were found to be invalid by the Supreme Court – a decision reversed on appeal last week; the use of tolls for trucks; and the impact extra heavy vehicles will have on residents’ quality of life.

Ms MacTiernan said she expected the documents to reveal that the project was cobbled together haphazardly without any cost benefit analysis by Senator Mathias Cormann, WA treasurer Mike Nahan and former federal minister Jamie Briggs.

It was then thrust upon the Main Roads department to make sense of.

“They employed one of the biggest national law firms to fight this case, flying over a barrister from Sydney – so I’m hoping something very interesting is in this document to fight so hard to resist letting the public know,” she told reporters.

The focus should be on expanding Fremantle Port’s outer harbour instead to prevent a congested port undermining the state’s economy, she said.

The state opposition has warned the government against signing construction contracts ahead of next year’s WA election, but Acting Premier Liza Harvey said the government would be forging ahead with the planning and tendering of contracts for a valuable project.

There are fears of a repeat of Victoria’s recent estimated $1 billion-plus in losses, when the Liberal government signed contracts on the eve of the election, which the new Labor government promptly tore up.