Railway signal workers in Scotland escalated the dispute over rosters today as they launched a ballot for strike action.
The decision follows an ongoing row with Network Rail and signallers in the Stirling area over 12-hour shifts but the RMT union is now preparing to ballot all Scottish signallers for industrial action over the issue.
RMT has been calling for staff to be moved to 12-hour rosters, which would see the number of working days change from five to three but the length of shifts rise from eight hours to 12.
RMT leader Bob Crow said: "Despite RMT making every possible effort to resolve this dispute through negotiation we have met with nothing but a brick wall and broken promises from management."
Network Rail has rejected the 12-hour rosters, saying it would add about £50,000 a year in operating costs.