Independent consultants were commissioned last year to look at what transport options were available to prevent passengers being held up in rush-hour traffic on the M8, with a completed report expected to be submitted by December.
Its findings are likely to prove controversial given the decision to axe the £210 million Glasgow Airport Rail Link in 2009 and a campaign by Labour to have the project reinstated.
A list of up to 50 options, including a ferry connection via the Clyde, has been reduced to 12 to 15 viable projects. A source said: "They've got rid of the nonsense and whittled it down to between 12 and 15 options. Each one will need to be appraised and the cost to benefit ratio assessed."
Its conclusions are likely to include long-term options such as a tram-train connecting with heavy rail services at Paisley Gilmour Street Station and cheaper proposals that could be implemented within the next five years, including a dedicated bus lane on the M8 to Glasgow.
Extending the Fastlink rapid bus service, which is due to be completed in 2015 and connect Glasgow to the Southern General, is another option.
The report has been commissioned by Glasgow Airport in partnership with Renfrewshire and Glasgow councils and Transport Scotland.
A spokesman for Glasgow Airport said: "Convenient and reliable access by a range of modes of transport is of fundamental importance to the operation and success of any airport."
Renfrewshire Council leader Mark Macmillan added: "The council is fully committed to working with partners to maximise the role of Glasgow Airport as a driver for the local and regional economy."