The proposals could cost between £1.5bn and £3bn
Up to £3bn could be spent on new train stations and a metro network in Glasgow under proposals announced by the Scottish Government.
New stations could be built to link the south and east rail networks, with another possible to link Central Station with Queen Street.
The metro would operate across existing "heavy" rail lines but could also be capable of going onto the street.
The proposals were outlined in the strategic transport projects review.
Its findings were presented at Holyrood by Transport Minister Stewart Stevenson.
The review also included proposals for 13 train services an hour between Glasgow and Edinburgh by 2016.
This would come with a reduction in the journey time between the two cities to about 35 minutes.
Also included in the review was a proposal for a massive development of park and ride projects to ease congestion into central Glasgow.
Councillor Alistair Watson, chair of Stratclyde Partnership for Transport, said: "The six projects proposed are for Bargeddie, St James, Glasgow Southern Orbital, Fullarton, Robroyston and Ayr (M77).
"These will make a significant change in the pattern of the commute into Glasgow and should mean much less car and much more bus and rail."