Christmas train strikes are set to cause widespread travel disruption, with services across the country crippled by a mass walkout.
Members of the Rail, Maritime and Transport (RMT) union are pressing ahead with further industrial action during the busy festive period.
Here is what passengers need to know about the latest strikes.
When are the rail strikes before Christmas?
There will be a rail strike from 6pm on Christmas Eve until 6am on 27 December.
Passengers are being urged only to travel on Christmas Eve "if absolutely necessary", as trains will stop running at around 3pm in most locations.
Members of the RMT voted in favour of more strike action at Network Rail and 14 train companies.
The RAC has warned that pressure on the roads will be heightened by the walkout, with traffic jams likely in cities and on major routes.
Are there any strikes planned for after Christmas?
There are further national strikes planned by the RMT for the new year.
Two 48-hour walkouts are scheduled on 3-4 January and 6-7 January.
There will be a separate strike by members of the Aslef union on 5 January.
Why are rail workers striking?
The RMT strikes have been called because of a long-running dispute over pay, jobs and conditions, as the cost-of-living crisis escalates.
Prime minister Rishi Sunak has accused RMT general secretary Mick Lynch of making rail workers "foot soldiers" in his "class war".
He said: "The unions are causing misery for millions, with transport strikes in particular cruelly timed to hit outings at Christmas."
Lynch had previous accused the government of "refusing to lift a finger to prevent these strikes".
What did the rail operators say?
Network Rail chief executive Andrew Haines has condemned the strikes, saying that "serious disruption" over Christmas is now "inevitable".
He added: "The RMT has deliberately chosen to try and ruin Christmas for millions of passengers and businesses.
"They're also intent on inflicting a monumental act of harm on an industry still desperate to recover from post-COVID challenges by sabotaging a vital £100m programme of rail upgrades planned for Christmas Day and Boxing Day."
Watch: What strikes are happening in December?