Strike action threatens to plunge the nation's railways into chaos when thousands of signalling and maintenance workers begin a 24-hour strike at 1830 BST on 29 June.
Bob Crow has urged the employers to enter "serious" negotiations
BBC News Online looks into the row and its background.
Why are railway staff set to strike?
The Rail, Maritime and Transport union is involved in a dispute with Network Rail over pay, pensions and travel benefits.
The union is complaining about the closure of the company's final salary pension scheme to new staff.
Combined with reduced travel benefits for new employees, "two-tier working conditions" are being created, the RMT says.
It is also unhappy with the three pay deals offered by Network Rail.
Workers have been offered a one-year rise worth 3%, a two-year deal of 3.5% now and 0.75% plus inflation in year two, or a three-year deal worth 3.2% now followed by rises with inflation, plus a 35-hour week by the end of the three years.
The union balloted around 7,000 members employed by Network Rail, who backed a strike by 2,947 to 2,246.
The ballot results were revealed in May.
Talks aimed at averting industrial action broke down over the failure to reach an agreement concerning pensions.
What is the employers' position?
"The result should come as no surprise as the RMT has failed to fully inform its members of the facts about the offers we have made," Network Rail chief executive John Armitt said.
"RMT's campaign of misinformation has proved successful."
The company says the defined contributions pension being offered to new staff is better than any other in the rail industry.
It has also stated that a signal worker's basic pay has risen by 72% over the past 10 years to an average of £32,500.
In response to the ballot result, it said: "With less than half of Network Rail's operations and maintenance employees in the RMT union, and only 38% of RMT members voting for strike action, this means that less than one in five of Network Rail's operations and maintenance employees have supported this strike action."
Disruption could be the worst to Britain's railways since privatisation
What impact will a strike have?
The walkout could be the worst for almost a decade, since the railways were brought to a virtual standstill by a pay dispute in the run-up to privatisation.
The RMT has co-ordinated its strike action with London Underground staff involved in a separate pay row to heighten the impact of the action.
A combined total of around 15,000 rail and Tube staff would be involved in the walkout.
Contingency plans, involving special timetables and the retraining of former signalling workers, will be outlined to the public later this week.
The company said it would "endeavour to run as many train services as possible during any strike, although plans cannot be finalised or released until closer to the
day of any potential strike action".
The Strategic Rail Authority said that every day of strike action would reduce the money available to settle the dispute.
Can a strike be avoided?
Following the ballot result, RMT general secretary Bob Crow wrote to Mr Armitt to ask if the company was prepared to hold "serious" negotiations.
John Armitt has accused RMT of a "campaign of misinformation"
The union previously accused the company of refusing to negotiate but added that if it was prepared to hold talks, "it is never too late to call off a strike".
But recent attempts to avert the industrial action have broken down.
What happens next?
Millions of rail commuters are likely to be affected by the strike unless last-minute negotiations lead to the action being called off.