Airtrack will link Surrey and Berkshire towns to Heathrow Terminal 5
A new delay has hit a planned £675m rail link between Heathrow Airport and stations in Berkshire and Surrey.
A public inquiry into BAA's proposed Airtrack line has been put back until the autumn at the earliest so concerns about level crossings can be discussed.
The line would connect Heathrow's Terminal 5 to London Waterloo, Reading and Guildford. Some Heathrow Express services would be extended to Staines.
But campaigners have said it would cause road delays at level crossings.
Phil Haugh, business editor of Rail magazine, said the scheme would lead to some crossings being down for about 40 minutes every hour - compared to about 20 minutes at present.
He said: "Planners will need to take into consideration the effect on level crossings as they would be down a lot more.
"But [the service] will not only be for the passengers flying into or out of Heathrow, it will also be for the people working at the airport.
"It will do something to cut road congestion if they were usually driving to Heathrow."
Sandra Tipler runs an underwear shop next to the level crossing in Sunningdale, Berkshire.
She said: "I think everyone will avoid the areas around the level crossings like the plague.
"To me it's a complete disaster, it's like another nail in the coffin after the recession."
Two rounds of public consultation were held in 2008.
BAA said following the objections more work was being done with local authorities, Network Rail and the highway authorities to look for solutions at level crossings.
BAA added: "This process is not anticipated to be complete until spring 2010.
"As a result, the public inquiry into the Airtrack scheme will most likely be deferred until autumn 2010."
It is the second time that the public inquiry has been delayed.
The track is still expected to be completed in 2016.