The Rail Maritime and Transport (RMT) union said Network Rail had offered to reopen its final salary pension scheme, the issue at the heart of the strike threat which would have caused misery to millions of commuters.
The offer was made during face-to-face talks today between Network Rail's chief executive, John Armitt, and the RMT leader, Bob Crow.
The union's executive agreed to suspend the 24-hour walkout, which was due to start at 6.30pm next Tuesday, to allow workers to vote in a fresh ballot with a recommendation to accept the deal.
The walkout would have crippled Britain's rail network with up to 90% of trains cancelled.
The RMT had called for the industrial action among 7,500 signallers and maintenance workers in a row over pay and pensions.
A walkout of thousands of London Underground workers had also been choreographed for the same 24-hours because of a separate dispute over pay and hours.
Network Rail had responded by mounting a legal challenge against the action which was due to be heard by a high court judge tomorrow.
The rail infrastructure company had claimed that as many as 1,000 people could have voted illegitimately to swing the result of a knife-edge union ballot.
Senior executives at Network Rail said that the RMT sent voting papers to members working at signal boxes which do not exist, to station cleaners who do not work for the company, and to people listed as working at "unknown" locations, in contravention of employment law.
Network Rail said 12 of the RMT's members were listed as working at a Brighton signal box which closed in 1983. Six were registered at a Newcastle site which shut 14 years ago and one was said to work at Garston signal box, Merseyside, which was gutted in a fire in 2002.
Some had feared that the Network Rail's offensive had threatened to further imperil relations with the union further but today's progress suggests the two sides are still able to reach some agreement.
