The Scottish Government will publish the business case for a high-speed rail link between Edinburgh and Glasgow in spring next year.
The project, which would almost halve journey times between the two cities to less than 30 minutes by 2024, was first unveiled last November.
Transport minister Keith Brown said work was now under way to produce a report outlining the costs and benefits of the proposal.
Mr Brown was speaking at Holyrood's Infrastructure Committee, where he updated MSPs on high-speed rail.
The committee was told that the Glasgow to Edinburgh high-speed route had the potential to boost rail capacity across the central belt, significantly reduce journey times and possibly lead to new stations being built.
"Cost-benefit ratio is a fundamental part of any transport projects we undertake," he said.
"We are just starting that process now and that is why we will have the report coming forward in spring next year."
He told the committee that, even at this stage, it was possible to see the potential for "pretty huge" economic benefits.
Mr Brown said the Scottish Government was also continuing to press the UK Government to extend its High Speed 2 (HS2) project north of the border, providing a fast connection between London and Glasgow.