The RMT union said workers will strike on August 18 and 20. It comes after after thousands of train operator and Network Rail staff walked out in a national strike in June.
The union had announced a strike for July 27, the day before the Commonwealth Games opens in Birmingham.
RMT general secretary Mick Lynch said: “The rail industry and the Government need to understand that this dispute will not simply vanish.
“They need to get serious about providing an offer on pay which helps deal with the cost-of-living crisis, job security for our members and provides good conditions at work.
“Recent proposals from Network Rail fell well short on pay and on safety around maintenance work.”
Mr Lynch added: “And the train operating companies have not even made us a pay offer in recent negotiations.
“Now Grant Shapps [Transport Secretary] has abandoned his forlorn hopes for the job of Prime Minister, he can now get back to his day job and help sort this mess out.
“We remain open for talks, but we will continue our campaign until we reach a negotiated settlement.”
Andrew Haines, Chief Executive of Network Rail, said: “By announcing even more strike dates, the RMT has dropped any pretence that this is about reaching a deal.
“It’s clear the best interests of passengers and our staff are taking second place to the union’s bosses’ political campaign.”
More to follow…