Britain's High Court has issued an injunction stopping a planned four-day rail strike next week.
Railway operator Network Rail argued that the Rail, Maritime and Transport Union's ballot of workers for the four-day walkout was invalid because of "inaccuracies and deficiencies".
After a hearing, a judge issued an order halting the strike.
Union Secretary-General Bob Crow said the ruling was "an attack on the whole trade-union movement".
Network Rail had said it would have to cancel 80 percent of its services if the stoppage by signalers went as planned.
The union is protesting cost-cutting measures, including the cutting of 1500 jobs, which it argues will undermine safety and threaten job security.
