Thousands of rail signallers will stage two one-day strikes in a dispute over pay, threatening chaos on the network.
A signallers' strike could close much of the nation's railways
The RMT union said the Network Rail workers voted by more than two to one to reject a pay deal which they said would amount to a two-year pay freeze.
Network Rail said it would seek talks with the union to try to reach a negotiated settlement.
Some 3,000 workers across Britain are due walk out at 1300 BST on 20 June and again at 2100 BST on 25 June.
The first strike will coincide with England's final World Cup group game against Sweden, when tens of thousands of football fans will be trying to get home to watch the game.
A second rail union, the Transport Salaried Staffs' Association (TSSA), narrowly voted against strike action over the same issue by 490 votes to 482.
The white collar union does not have a history of supporting strike action, but its officials conceded that the close result suggested industrial relations had deteriorated.
RMT members voted by 2,104 to 970 to take industrial action and boss Bob Crow said afterward that the employer's "penny-pinching" pay offer was "unacceptable".
"Network Rail's offer would see our members' pay stand still in real terms for two years," he said.
"And it would stall the introduction of a 35-hour week they were promised by March for another year."
Network Rail chief executive John Armitt said he was "disappointed" by the ballot result, saying a strike would damage public confidence in the railways.
But he said the firm had been planning for a strike "for some time", though it would still seek talks.
"In the event, we will do all we can to run as many services as possible and minimise the disruption caused to our customers," he added.