The state government in Queensland announced plans on Monday for a new $A5 billion public transport tunnel in Brisbane.
The ABC reports the 5.4km tunnel from Dutton Park to Bowen Hills will have trains operating on the bottom level and buses on top.
Transport Minister Scott Emerson said previous projects had price tags of more than $A5 billion for the rail and almost $A3 billion for the bus.
He said construction will start in 2015 and take six years to complete.
Treasurer Tim Nicholls said the Government will ask the private sector to be involved.
"We can certainly be looking at infrastructure bonds," he said.