Queensland Premier Campbell Newman says his Government is coming up with a cheaper way to get more trains across the Brisbane River.

The Bligh government had planned a tunnel under the river with new stations at a cost of about $8 billion.

Last year, the Newman Government said it could deliver cross-river rail for $4.5 billion with funding from the Commonwealth.

But the new Federal Government will not contribute to the project, so Mr Newman says an alternative plan is being developed.

"We are currently reworking cross-river rail," he said.

"We are turning it into a project that delivers lots more bang for less buck that solves not just the rail issues but hopefully bus issues.

"It's a comprehensive public transport solution for the Brisbane CBD."

State Transport Minister Scott Emerson says the Abbott Government will contribute more to roads projects, freeing up funding for rail.

But Opposition Leader Annastacia Palaszczuk says Mr Emerson and the State Government must commit to a timetable.

"Now is the time for Scott Emerson as the Transport Minister to say is he going to support Cross River Rail yes or no - how is the State going to fund it," she said.