Unions today declared a national dispute on the railways in a row over control centre jobs, raising the threat of industrial action.
The Rail Maritime and Transport union (RMT), Transport Salaried Staffs Association and Unite are seeking guarantees of no compulsory redundancies over plans by Network Rail to reduce the number of electrical control rooms.
The RMT said managers had refused to guarantee there would be no compulsory job losses so it had "no option" but to declare a dispute.
General Secretary Bob Crow said: "The electrical control room operators deliver a critical service in terms of running the nation's railways and the network cannot operate without them.
"We have sought through negotiation a perfectly fair and realistic agreement on no compulsory redundancies at this time of major reorganisation but Network Rail managers have failed to accept that and have plunged us into this dispute as a result.
"Early in the New Year the three unions involved will meet to discuss a joint strategy, including the use of industrial action, to protect our members' jobs and livelihoods and to prevent a wave of compulsory redundancies from being bulldozed through by the company."
A Network Rail spokesman said: "Network Rail has been in discussions with the union representatives of our people who work in electrical control rooms about the potential future structure of electrical control and impact on current locations.
"As part of these discussions, we have proposed a working party with the unions, to discuss in more detail the company's thinking, before Network Rail is in a position to put forward a formal proposal.
"The unions have asked for a guarantee of no compulsory redundancies, without which they would not engage. We have reaffirmed our intention to manage the process through redeployment and voluntary means and we want to continue further discussions.
"We urge the trade unions to resume constructive talks. Network Rail is committed to a fair resolution which also secures a modernised, more reliable and more efficient way of managing electrical power supply to our network."