A strike by workers on Southern Railway was set to disrupt weekend services, including the travel plans of thousands of people hoping to attend one of the country's most popular bonfires.
Members of the Rail, Maritime and Transport (RMT) union are staging a 48-hour walkout, which ends at midnight on Saturday, in the bitter dispute over the role of conductors.
More action is planned in the coming weeks, and the union has escalated the row by calling strikes over Christmas and the New Year.
No trains will stop on Saturday at Lewes, where tens of thousands of people usually attend the town's bonfire.
Southern blamed the need to ensure public safety, saying it would not be able to operate any rail or replacement bus services to the Lewes area from Saturday afternoon.
Tens of thousands of people attend the bonfire, many usually travelling by train to the event, which is a major fund-raising opportunity for charities.
Southern condemned the latest stoppage as "spiteful and vindictive" and warned of disruption to services even though it planned to run more trains than during previous strikes.
RMT general secretary Mick Cash said support for the latest walkout was "absolutely rock solid", adding: "Passengers know that Southern Rail under GTR is an unmitigated disaster that puts profits before public safety. That is the issue at the core of this dispute.
"The solution to this dispute can be achieved easily through a cast-iron guarantee of a second, safety-critical member of staff on all current services with a guard.
"Once again the union is demanding that Transport Secretary Chris Grayling gets out of his bunker, gets hold of this basket-case company and gets round the table for serious negotiations."
A Southern spokesman said: "These strikes are spiteful, vindictive and pointless given the majority of conductors have now signed up to the new on-board role.
"This has never been about safety - it's purely about the RMT hanging on to outdated working practices and union power."
The union accused the company and the Government of "sheer pig-headedness" as it announced that its members will strike from 0001 on December 22 until 2359 on Christmas Eve, and again from 0001 on New Year's Eve until 2359 on January 2, when new fare rises come into effect.