WA Labor’s Metronet rail plan has been boosted by federal opposition leader Bill Shorten pledging federal funding and labelling it his number one infrastructure priority for Perth.
Metronet was the centrepiece of the state opposition's 2013 election campaign, when the party estimated it would cost $3.8 billion, although the Liberal state government's then-Treasurer Troy Buswell claimed it would cost $6.4 billion.
Tim Marney, WA's Under Treasurer at the time, estimated the project would cost about $500 million more than Labor claimed, but $2 billion less than the Liberal estimate.
Under the plan, rail links will be run right up to suburbs on the edge of the city's urban sprawl in a bid to ease road congestion and give commuters a swifter alternative to buses.
Labor relaunched Metronet last year, saying it could not give a firm figure for the entire proposal, but the key planks would cost between $2.5 billion and $3 billion.
These elements include the Forrestfield-Airport rail link, which the Liberal state government has also undertaken and budgeted, and fixing dangerous level crossings.
The opposition says it is still working on the final aspects of Metronet and will release the final cost estimate closer to the election in March next year.
Before the last poll, the plan was matched by the WA Liberal's MAX light rail plan - but that scheme was put on ice as the state government struggled with deficits and mounting debt.
Mr Shorten told reporters in Perth that he'd throw his support behind Metronet if Labor won the federal election, contributing Commonwealth grants.
The rest of it would be funded with debt, he said.
"We want to ease the congestion, we want to improve the productivity - people shouldn't spend their whole days waiting in traffic to get to and from work," Mr Shorten said.
WA Labor leader Mark McGowan couldn't say how much of the project's multi-billion dollar price tag would be paid for with borrowings, but he was confident the party's federal leadership would eventually provide firmer details about planned Commonwealth contributions.
"Over time, there will be more forthcoming figures," Mr McGowan said.
"It will be built over a timeframe that we can afford.
"If Labor is elected at a federal level and if Labor is elected at a state level, you'll see Metronet come on stream pretty quickly."