Airtrack plans to link Surrey and Berkshire to Heathrow Terminal Five
Waiting times at level crossings in south-west London could increase if a proposed rail link to Heathrow airport gets the go-ahead, a council has said.
Richmond Council urged residents to take part in a public consultation on Airtrack as it said the current average waiting times will 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.
The additional rail services will increase congestion and would lengthen the wait at barriers at Barnes, Mortlake and North Sheen, the council said.
Councillor David Trigg, cabinet member for traffic and transport, said: "At peak hours at the moment the downtime is roughly 30 minutes out of every 60.
"This is causing considerable congestion and problems in the vicinity of those crossings and beyond - quite frankly this is not acceptable."
The council said it "fully supports" the project but the new service could adversely affect existing commuter services.
Susan Kramer, MP for Richmond Park, said: "Our communities don't parallel the railway lines - they run across them, north to south.
"Cutting our communities in half will not only make life difficult for local people, but could also cause significant delays to emergency services that need to cross the railway."
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."
The public consultation ends on 15 December.