A new wave of strike action across the railways has been announced in March and April in the long-running dispute over pay and conditions.
Members of the Rail, Martine and Transport union (RMT) will walk out on March 16, 18 and 20, and April 1, at 14 train operators.
It comes just days after the major union rejected a "dreadful" pay offer from Network Rail.
Last week the RMT branded a proposed Network Rail shake-up "unsafe, unhealthy for our members and unworkable" - but called for further meetings to resolve the long dispute.
Speaking on Thursday the General Secretary Mick Lynch said: "Rail employers are not being given a fresh mandate by the government to offer our members a new deal on pay, conditions and job security.
"Therefore, our members will now take sustained and targeted industrial action over the next few months.
"The government can settle this dispute easily by unshackling the rail companies."
He also accused the Government of a "stubborn refusal to do so", as the union also announced a "very disruptive" overtime ban to coincide with the new strike action.
Mr Lynch added: "Ministers cannot continue to sit on their hands hoping this dispute will go away as our members are fully prepared to fight tooth and nail for a negotiated settlement in the months ahead."
But Network Rail's chief negotiator Tim Shoveller accused the union's leadership of "choosing politics over people".
He claimed: "During months of talks we have made multiple concessions, compromises and offers in our determination to secure a deal.
"Thousands of employees are telling us they want the improved offer that we have tabled, an offer worth at least 9% over two years - rising to over 14% for the lowest paid, provides job security with no compulsory redundancies and 75% discounted rail travel."
He added "Further strikes will disrupt passengers and cost employees money - while changing nothing as our package of very modest reforms continues.
"Their action is condemning us all to a long and drawn-out dispute with no obvious end in sight, and is only harming the very industry and people it claims to be here to protect."
It comes as the country continues to face mass walkouts in other sectors, including the NHS, civil service, universities, and schools.
Ministers have so far resisted negotiating over pay with public sector bodies, including the health service - despite the surging cost-of-living and sky-high inflation.
The Royal College of Nursing (RCN) has also accused ministers of refusing to engage in talks and on Thursday announced a major escalation of industrial action.
