There will be a crackdown on people planning to join a festive tradition of walking on a Cumbrian viaduct.
The Christmas and Boxing Day walks along Arnside Viaduct when passenger trains do not run have grown in popularity.
But Network Rail and the British Transport Police are warning people not to make the attempt this year or risk being prosecuted and fined.
It was dangerous as maintenance trains could be on the line, they said.
Supt Pete Mason, from British Transport Police, said: "It has gained in popularity and we are aware now that last year it culminated in a couple of hundred people walking across the viaduct.
"It is dangerous. The actual viaduct - there is no proper walking space for people. It is on the rail and it is inherently dangerous for people to walk across that viaduct even more so in the current weather."
He said officials had decided to take action because of the growing popularity of the event.
He said while there would not be passenger trains, maintenance trains could run on the line.
But people who have taken part in the past said they were not happy because it was stopping what had become a tradition.
They said they did not remember a train running on the line on those days in the last few years.