A study into whether improved rail inks to Heathrow Airport would be viable have found there to be a strong case for the scheme.
Work on building Terminal Five has already started
The investigation looked at whether trains could run directly to the new Terminal Five from Surrey and Berkshire and London.
It found the service would provide significant economic advantages for businesses and passengers.
Called AirTrack, the new rail link would take passengers straight to the terminal from Reading, Guildford and Waterloo instead of them having to wait for a connecting bus or train.
A predicted five million passengers would use AirTrack, according to the study, of which a third would be travelling to and from Heathrow.
It would also encourage people to leave their cars at home.
The study predicts AirTrack would be up and running within 10 years as it would use existing track and would only need a short length of new railway route.
The AirTrack scheme is being promoted by the AirTrack Forum, chaired by Surrey County Council.
Other organisations in the group include British Airways, Transport for London, the South East England Development Agency, the Highways Authority and business groups from Surrey, Berkshire and Hampshire.
The study, by Atkins Rail and PriceWaterhouse Cooper, on behalf of the forum, will now be submitted to the Strategic Rail Authority and the government.
George Burnett, Airtrack Forum chairman, said: "Congestion on the roads on the approach to the airport and the surrounding areas is reaching unacceptable levels daily.
"AirTrack is the solution to help alleviate these traffic problems and the outline business case (the study) proves it to be a realistic and financially viable business proposition."
Heathrow's Terminal Five was given the go-ahead in 2001 after a four-year public inquiry.
It will be capable of handling 30 million passengers a year and is due to open in 2008.