Thousands more railway workers will vote on strike action in growing disputes over pay and jobs which could lead to even more travel chaos this summer.
The Transport Salaried Staffs Association (TSSA) will ballot more than 6,000 of its members at Network Rail from 20 June to 11 July.
It comes after members of the Rail, Maritime and Transport (RMT) union at Network Rail and 13 train operators agreed to go on strike on 21, 23 and 25 June in similar disputes.
The RMT and Unite are also taking part in industrial action which will affect the London Underground on 21 June.
The TSSA previously announced strike ballots among its members at four rail companies - Avanti West Coast, CrossCountry, East Midlands and West Midlands Trains.
Members of Aslef, the drivers union, are striking later this month at Hull Trains, Greater Anglia and Croydon Tramlink.
TSSA members at Network Rail work in operational, control, management and safety-critical roles on rail services across the UK.
The union is asking for a guarantee of no compulsory redundancies this year, no unagreed changes to terms and conditions and a pay increase that reflects the rising cost of living.
Staff have not had a salary rise for the last two to three years, the TSSA said.
If they vote for a strike, it could be held from 25 July.
'Summer of discontent'
TSSA general secretary Manuel Cortes said: "We could be seeing a summer of discontent across our railways if Network Rail don't see sense and come to the table to face the concerns of their staff.
"Network Rail staff are asking for basic fair treatment - not to be sacked from their jobs, a fair pay rise in the face of a cost-of-living crisis and no race to the bottom on terms and conditions.
"Fat cat bosses have so far refused these completely reasonable requests, leaving us with no option other than to ballot for industrial action, something which is always a last resort."
He said Network Rail have "dragged their heels" at every stage of pay talks, which began in April.
More talks will be held on Thursday in a bid to agree a deal.
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A Network Rail spokesman said: "Now is not the time for the TSSA to be jumping on the RMT 'strike bandwagon'.
"Positive pay talks were in full swing with a 'no-strings' pay offer of 2.5% on the table, with the potential for more if connected to productivity and efficiency gains, so this news is both premature and deeply disappointing."
A Department for Transport spokesman said the ballot was "disappointing and premature", adding: "Taxpayers across the country contributed £16bn, or £600 per household, to keep our railways running throughout the pandemic.
"The railway is still on financial life support, with passenger numbers 25% down and anything that drives away even more of them puts services and jobs at risk."