Ore Rail workers are set to strike later this month to further worsen the dispute, threatening travel chaos for commuters.
Unite announced that its members employed as electric control room operatives by Network Rail (NR) will join other rail unions in taking action on August 18 and 20.
The Transport Salaried Staff Association (TSSA) also announced that thousands of its members in NR would go on strike on the same dates.
TSSA said it issued the notice after asking NR for “clear assurances and clarifications” on job security and working practices.
The union said no such assurance was forthcoming and the 14-day notice, required by law, had been given.
General secretary Manuel Cortes said: “Our union has a strong mandate for strike action across these grades at Network Rail and the walkout will have a huge impact.
Our union has a strong mandate for strike action at Network Rail in these grades and the walkout will have a huge impact.
“Our members are only asking for basic fair treatment: not to be fired from their jobs, a fair pay rise in the face of the living crisis and no race to terms and conditions.
“No one takes strike action lightly, but we are left with no choice. Our graders and controllers are a force to be reckoned with. Without them the rail network cannot function, it’s that simple. .
“Sadly, it now looks like we’re going to see more disruption on our railways this summer. It’s time the company bosses told the government they have to get a grip.”
“Our door remains open but only if there is a meaningful offer on the table that will give our members the fair deal they need to keep our rail network safe every day of the year.”
Unite said electric control room operatives play a vital role as they are responsible for managing and controlling the supply of electricity to the rail network.
General secretary Sharon Graham said: “Our members have played a vital role in keeping the rail network operational throughout the pandemic, ensuring essential workers and goods can be transported.
“To thank them for their sacrifices from their employers is a mocking offer that amounts to a kick in the teeth.
“Unite is fully committed to defending the jobs, pay and conditions of its members.
“Our members at Network Rail will continue to have the full support of the union until this dispute is resolved and workers receive a fair pay agreement.”
The operators are based in control rooms in Brighton, East Sussex. York Paddock Wood, Kent; Raines Park, South London; Romford, Essex and Selhurst Road, South London.
Unite said its members had not received a pay rise for three years and were increasingly struggling to make ends meet due to the cost of living crisis.
United national officer Harish Patel said: “The strike action by Unite members will undoubtedly cause further disruption to rail services but the dispute is entirely Network Rail’s own.
“Our members expect and deserve a pay rise that addresses the cost-of-living crisis they face.”
Members of the Rail, Maritime and Transport Union and TSSA are striking on August 18 and 20, while RMT members will stage a 24-hour walkout on London Underground on August 19.
Members of Aslef, the drivers’ union at nine train companies, will strike on August 13 following industrial action last month.
Tim Shoveler, Network Rail’s lead negotiator, said: “We are doing everything we can to avoid disruption for our passengers later this month, but it looks like our unions will have more on August 18 and 20. are coordinating their strike action to have a greater impact than
“We urge all our unions to agree to a contract with us that is fair to their members, our employees, and affordable to taxpayers and commuters, and we believe that is only right. That members give their feedback on our offerings.”