Airtrack plans to link Surrey and Berkshire to Heathrow Terminal Five
Concerns about increased waiting times at level crossings because of a rail link to Heathrow Airport have come from a Surrey council.
Runnymede Council became the second authority to raise concerns on Thursday after Richmond Council also said the wait at crossings would rise.
Airtrack will link stations in Berkshire and Surrey to Heathrow's Terminal Five.
Airport operator BAA said it is working to mitigate any potential problems.
Runnymede Council leader John Furey said the authority had strong concerns about level crossing down times in Egham.
He said the council backed the Airtrack scheme for its national economic benefit and reduction in traffic on the M25.
But he said there were no proposals to address the "significant" impact on four level crossings in Egham and Addlestone.
He said the barriers already led to long queues and additional trains serving Heathrow would make them "even worse".
Mr Furey said: "We already have a major problem with level crossings causing unacceptable traffic delays on our roads and making this worse is simply not acceptable."
A spokesman from BAA said: "We are currently considering the impacts of proposed services along the entire Airtrack route, including effects on local level crossings.
"No conclusions have been drawn yet but we're looking at ways to mitigate any potential problems by working with local authorities and highway authorities."
Consultation on Heathrow Airtrack runs until 15 December.