Union members from the Transport Salaried Staffs’ Association and Unite have confirmed they will take part in a series of already-planned rail strikes scheduled for October.
The industrial action is being held over disputes regarding pay and working conditions, with a strike planned for 8 October.
"To be faced with a three-year pay freeze during the worst cost of living crisis in decades is disgraceful,” Unite's general secretary Sharon Graham said in a statement.
"We would much rather find a fair negotiated solution to this now long-running dispute, but we simply have no choice," TSSA general secretary, Manuel Cortes said.
Workers from fifteen operating companies, including Network Rail, will strike on October 1 and October 5, due to the continuing dispute over job security, pay and working conditions.
These strikes will bring the railway network to an effective standstill, according to the RMT Press Office, which said it “received no further offers from the rail industry to help come to a negotiated settlement.”
Mick Whelan, of the Aslef union, said “withdrawing our labour is always a last resort for this trade union.”
Significant disruption is expected, particularly for the Conservative Party Conference in Birmingham due to be held between 2 and 5 of October, and the London marathon on October 2
Railway cleaners contracted for Avanti West Coast services are also set to walk out this Friday for 24 hours, as RMT argues members are “languishing on poverty wages.”
Unions had cancelled strikes that were planned for last week following the passing of Queen Elizabeth II.
Shares in FirstGroup eased 0.3% to 118.6p.