Heavy trucks will be subject to a per-kilometre toll all the way from Muchea, north-east of Perth, to Fremantle Port to help pay for a $1.6 billion freeway-grade 13km road link, including construction of the controversial Roe Highway stage 8.
WA's first toll road - the Perth Freight Link project - will see the State Government put up $591 million of new money, in addition to $59 million already committed to upgrades of High Street through East Fremantle and $925 million from the Commonwealth.
The freight link will run west of the Kwinana Freeway across the Beeliar wetlands to Stock Road, then north towards Leach Highway/High Street, then west to Stirling traffic bridge in Fremantle.
The State Government's funding contribution, which will be included in next week's mid-year Budget review, will add to State debt in the medium term.
Beyond 2019, when the road is expected to open, the State Government will begin to collect revenue from the heavy vehicle toll.
The Government could eventually sell the revenue stream from the toll to the private sector in return for an up-front lump sum payment, which would in theory pay off the debt.
The cost of the per-kilometre toll is subject to further modelling and is unknown, but Transport Minister Dean Nalder said preliminary work suggested the new road would deliver benefits of 45 cents per kilometre in time savings, reduced fuel, maintenance and road crashes.
The toll would be set at less than the value of the per-kilometre benefits.
The Government believes the Perth Freight Link will slash 9.5 minutes off travel time between the Kwinana Freeway and Fremantle Port, bypassing 14 sets of traffic lights.
The Government believes the project will take up to 500 trucks a day off Leach Highway and improve access to the Murdoch medical and education hub.
Transport Minister Dean Nalder acknowledged construction of the Roe 8 section of road through the environmentally sensitive Beeliar wetlands would be contentious but he insisted the environmental impacts would be managed.
6ha of the Beeliar wetlands would be destroyed during construction of the Roe Highway extension. Picture: Mogens Johansen/The West Australian
About 38ha of bush and wetlands would be destroyed during construction, including about 6ha at Beeliar, but this would be offset by the reservation of about 400ha elsewhere which would be designated Bush Forever land.
The Government claimed the project would save 450,000 tonnes of carbon dioxide emissions by 2031, and public access to the wetlands would be upgraded.
Mr Nalder insisted the heavy vehicle charging - which applies to sections of road presently toll-free and $1 billion Gateway WA project around Perth airport and the $1.2 billion Swan Valley bypass project - would be a win for the trucking industry, with the toll set at less than the benefits delivered by the new road.
"Given we are creating a freeway system that will run from Stirling Bridge all the way to Muchea, we are looking to defray the cost over the whole extent of that freeway system," Mr Nalder said.
"The economic modelling suggests there is an economic net benefit of ... up to 45 cents a kilometre.
"This needs to be a win-win for industry."
Senator Mathias Cormann said the project would result in "tangible benefits for business".
"It really is a matter here of sharing some of the costs," he said.
The Government claims modelling shows a cost benefit ratio of $2.80 for every $1 invested in the project refused to release the business case for the road project, saying there were commercial sensitivities.
The State Government will award two tenders - for the Roe 8 section and for the Stock Road to Fremantle section - and hopes construction will commence in early 2016.
It is understood the project would involve mandatory GPS technology to be installed for all trucks over a certain size or weight, which would be subject to the per-kilometre charge. Such technology has been rolled out in New Zealand.
Shadow transport minister Ken Travers said the Government had broken a major promise, ushering in the era of toll roads.
"They said there would be no toll roads. It doesn't matter how they dress it up, this is a toll on our trucks and it will spread to cars," he said.
"When Mr Barnett cancelled the public transport projects (promised at the election) it was because he didn't have the money.
"Now they have found to money to be able to dance to the tune of Canberra, when it comes to building roads."
Mr Travers said the road would not solve either Perth's freight challenge or congestion problems.