The new £15 billion Crossrail service may not stop at Heathrow after a row with the airport’s owners.
A High Court will rule whether Crossrail trains should be charged for each time they travel to Heathrow.
Crossrail is the new 73-mile development running from areas east of London through 42km of tunnels and out to the west. The project is building 10 new stations and upgrading 30 more and is expected to ease congestion on the crowded London Underground.
The airport wants to charge £570 for each train using its track and an operational fee of £107. This could drive up Crossrail costs by £42 million a year, which would then see ticket price increases.
Heathrow wants to recoup some of the £1 billion it spent on building the track 20 years ago.
Rail regulator, The Office of Rail and Road (ORR), previously decided Heathrow could not charge trains for using the line.
The airport said it wanted to "ensure track access charges were fair".
A spokesperson for Heathrow Airport Limited said: “We are committed to increasing public transport to Heathrow and look forward to the arrival of Crossrail in May 2018. We need to ensure that track access charges are fair and are waiting on a ruling from the courts on whether the regulations apply and if so, their correct application to costs.”
The ORR said: “In May 2016, taking into account representations and evidence from affected parties, including considerable documentation and submissions from Heathrow Airport Limited (HAL), we decided HAL is not permitted to introduce all of its proposed new charges for train operators to use its track, which links Heathrow Airport to the Great Western main line.”