More than 40,000 workers from Network Rail and 15 train operators will strike again on 8 October, their union says.
The RMT said it would be "effectively shutting down the railway network" as part of a long-running dispute over pay, jobs and conditions.
It will come just a week after an even bigger strike by members of RMT and the train drivers union Aslef, which will leave just 10% of UK services running.
A smaller Aslef strike is also planned on 5 October.
Network Rail warned passengers to expect very significant disruption and asked people to only travel if absolutely necessary.
It said that full timetables for upcoming strike days would be published soon.
RMT general secretary Mick Lynch said the union had met with new Transport Secretary Anne-Marie Trevelyan to discuss the disputes.
"However, as no new offer has been tabled, our members have no choice but to continue this strike action," he said.
"We will continue to negotiate in good faith, but the employers and government need to understand our industrial campaign will continue for as long as it takes."
The latest action comes after a series of large-scale rail strikes in recent months as unions seek pay increases in line with the rising cost of living.
The RMT, which represents rail workers including guards and signalling staff, had already announced its 40,000 members would strike on 1 October -
the day before the London Marathon.
Train drivers at 12 operators who are members of Aslef will also walk out on 1 October, before holding a second strike on 5 October.
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