A £140,000 study is to be carried out to see if train links to Heathrow Airport can be improved.
Work on building Terminal Five has already started
The investigation will look at whether trains could run directly to the new Terminal Five from Surrey and Berkshire and London's Waterloo station.
The scheme would take passengers who currently have to take a connecting train or bus straight to the terminal on a new railway line.
Those backing the new line claim it could be built within five to 10 years and would cut road congestion.
Due to open 2008
Terminal Five was given the go-ahead in 2001 after a four-year public inquiry.
It will be capable of handling 30m passengers a year and is due to open in 2008.
The proposed new rail scheme, being called AirTrack, would run on a new stretch of line north of Staines in Surrey.
Trains would run directly to Terminal Five from Guildford in Surrey, Reading in Berkshire and from Waterloo.
The AirTrack scheme is being promoted by a group called 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.
Impact on the environment
The forum has awarded consultancy group Atkins Rail £140,000 to carry out a detailed investigation into the viability of the scheme.
It has been asked to determine construction and running costs, and look at the schemes' impact on the environment and assess benefits for the national rail network and the local area.
An AirTrack Forum spokesman said it would then be looking to make an official bid to the Strategic Rail Authority next year to try and secure government funding for the project.
Chairman George Burnett said: "AirTrack is badly needed - in fact the original planning permission granted for the building of Terminal Five at Heathrow required space to be provided for just such a service.
"At the moment, getting to Heathrow from a variety of locations in the South East can be a convoluted business, involving several changes of train or bus.
"The only viable alternative for many is to drive there on already
"The UK desperately needs new rail schemes which are practicable, affordable and which can be delivered in the next five to 10 years, and the Forum believes that AirTrack fits these criteria."