The left-led Rail, Maritime and Transport union yesterday announced that it had scheduled 24-hour stoppages beginning at 6.30pm next Tuesday. The strikes were condemned by employers, passengers' groups and the government.
Signallers, station staff and maintenance workers at Network Rail are in dispute with the infrastructure company over plans to close its final salary pension scheme.
Network Rail said the strike would inevitably cause "major disruption", despite contingency plans to use more than 200 retrained senior executives to keep signal boxes open.
A simultaneous stoppage on London's tube system will take place as part of an RMT campaign to secure a four-day working week. The underground carries 3 million passengers a day - more than all of the country's overground trains put together.
The strikes could still be averted by negotiations. But if they go ahead, they could lead to an early night for thousands of businesses on Tuesday as employees try to get home before services stop.
There could be knock-on disruption for football fans flocking to bars to watch the first semi-final of Euro 2004 next Wednesday, with the first trains unlikely to start running much before 7pm.
The transport secretary, Alistair Darling, urged the RMT to reconsider.
"At a time when improvements are starting to come through on the tube and trains, the last thing passengers need is a strike," he said. "It would cause massive inconvenience and needless disruption to the travelling public. It is totally unnecessary."
Bob Crow, the RMT's general secretary, said Network Rail had refused to budge on pensions, despite progress in settling parallel disagreements over pay and travel benefits.
"Our ballot for industrial action may have brought Network Rail to the negotiating table, but on pensions they have simply sat there with their arms folded," he said.
He criticised Network Rail's recent award of six-figure performance bonuses to board members as a "grubby reward" to senior executives for pulling the plug on the staff retirement fund.
Network Rail said that the closure of the pension fund would have little impact on existing employees and would affect only new staff.
Its chief executive, John Armitt, said: "This strike is wholly unnecessary and comes as a surprise when talks had progressed so constructively."
Intercity lines and commuter services into big cities will be given priority by planners working to keep a limited number of services running. The issue is likely to cause tension among train operating companies, which will be lobbying for their lines to remain open.
On the underground, the RMT wants employees to work a four-day week of no more than 35 hours. An earlier walkout on the day of the capital's mayoral election was averted only by the last-minute intervention of the mayor, Ken Livingstone.
There was no immediate comment from LU. But a spokesman for Metronet, the biggest private sector group maintaining the tube, said it had given "firm commitments" on a 35-hour week and was due to hold more talks with the union today.
"The announcement by the RMT is breathtaking for its sheer audacity," said a Metronet spokesman. "It seems the RMT is determined to strike come what may. It is the RMT who are not serious about resolving the issue and it is Londoners who will suffer the consequences."
