The planned Brisbane Underground Bus and Train (UBAT), announced by the state government on Sunday, will feature a double decker design with trains on the bottom and buses on top.

Brisbane's planned Underground Bus and Train tunnel.

The Brisbane underground bus and train tunnel will cost almost $30 million – before a single piece of ground is broken.

In response to a question on notice, Transport Minister Scott Emerson laid out the costs but added that the planning and development costs have been budgeted at “approximately half of what was spent by the previous government on cross river rail”

Identified as one of the city’s most crucial projects, the government has proposed a 5.4 kilometre public transport link from Dutton Park to Bowen Hills, with stations at Woolloongabba and George Street.

A screengrab from the fly-through of the new Brisbane Underground Bus and Train (UBAT), announced by the state government on Sunday.

The UBAT will link Dutton Park to Bowen Hills.

Under the previous government, the project was costed at about $8 billion.  The Newman government says it can do it for $5 billion.

So far it has spent $2.85 million on the development of a 358 page “concept design business case” and Mr Emerson estimates another $25 million will be needed for the “production of the Underground Bus and Train reference design, environmental impact statement, business case and supporting documentation”.

Mr Emerson said he expects the reference design, EIS and business case to be finished by mid next year.  Construction will begin in 2015 and is predicted to take six years to complete.

The Newman government plan will see a 15-metre wide double decked tunnel built below the Brisbane river, with buses to run above a train line.

The government plans on working with Brisbane City Council to build the project, but will also be looking to the private sector to help fund it.