A Perth sustainability expert has slammed the state government's idea to build an underground rail system from the CBD to Morley as "nonsense" claiming the outer suburbs did not have the density to justify the expensive transport solution.
On Monday, Transport Minister Dean Nalder confirmed the state government was quietly considering an underground rail line to Perth's north-eastern suburbs which could eventually service Ellenbrook, a suburb promised a rail line in 2008.
The subway solution was being discussed as an alternative solution to $2 billion MAX light rail system project promised by the government in the 2013 election which was later deferred.
It comes just seven months after Mr Nalder spruiked bus lines as a cheaper alternative to the beleaguered light rail project.
Curtin University sustainability policy institute research fellow Jemma Green told Radio 6PR on Tuesday morning the proposed eight-kilometre underground rail could cost $7 billion and would drain most of the transport budget for decades to come.
"[Minister Nalder] is spending money on projects that are not going to happen because they are so expensive that it's just absolutely unfeasible," she said.
"I don't understand why we're not working on things that actually are cost effective."
"Putting these fanciful ideas of underground rail out to the northern suburbs, the expense of that is going to mean that it's never going to happen anytime soon, but buses will, so it's just smoke and mirrors so they can push the bus agenda."
Ms Green said the government should be considering above-ground heavy rail to the eastern corridor in the near future coupled with a light rail system for the inner-city, higher density suburbs.
Shadow Transport Minister Rita Saffioti claimed the latest solution to Perth's traffic congestion was a more expensive version of Labor's plan to build an above-ground rail out to Morley and Ellenbrook.
"They said at the time that you don't need heavy rail to serve the north-east corridor and now they're copying Labor's plan for making it far more expensive," she said.
"The government is all over the place on public transport, they've been there nearly eight years and they have been flip-flopping around on public transport plans.
"They've broken a number of promises and have demonstrated chaotic planning."
Nalder demonstrates yet again that the Liberals cannot be trusted on public transport. More chaos and broken promises.— Rita Saffioti (@Rita_Saffioti) February 2, 2016
Mr Nalder said the government was using $5 million remaining in the MAX 'account' to engage independent research into a subway and compare it to that already done on light bus and MAX.
While not committing MAX to the dustbin with certainty, he said he had "challenged" whether it was the best solution claiming underground rail could carry four times the capacity of light rail.
The underground train would go past Edith Cowan University's Mt Lawley campus to Morley, probably to the Galleria shopping centre.
"I can't commit one way or another but what I said yesterday is that for the capital costs on the capacity you get on light rail versus heavy rail, I do favour, slightly, that heavy rail option," Mr Nalder told Radio 6PR on Tuesday.
Mr Nalder hopes to take a proposal to cabinet early in the second quarter of 2016 and thereafter provide more information to the public.
Parliamentary estimates reveal the government has been considering the underground rail as an alternative to light rail since December 2014 when it described the subway idea as a 'butchers paper' plan with a rough completion date of 2050.
