After voting by a margin of nearly three to one for action, nearly 12,000 Network Rail staff in England, Wales and Scotland will walk out of work for 30 hours from midday on Saturday.
Workers are also refusing to undertake any overtime or "on-call" work between 6am Saturday to 6am Monday.
The RMT says the dispute follows months of fruitless talks aimed at achieving a single set of terms and conditions for maintenance staff, many of whom transferred into Network Rail from the private sector.
"The company has been using the talks to try to drive down our members' conditions, but our reps were shocked when the true extent of the company’s agenda was revealed to them last week," RMT General Secretary Bob Crow says.
Network Rail says it is disappointed by the decision as negotiations were continuing with the next meeting scheduled for two weeks.
Rail workers are demanding higher pay and a 34-hour week across the board.
Network Rail says contingency plans are in place to cope with the strikes.