Railway signal workers are going on strike again in a dispute about shift patterns.
The RMT union has been trying to negotiate 12-hour shifts for signallers in the Stirling area but says Network Rail has so far refused.
The dispute has been running since April and signallers were on strike on Christmas Eve.
Members in Stirling will again strike on Hogmanay and Saturday January 5.
All signalling members in Scotland are being consulted on escalating the action, the RMT said.
General secretary Bob Crow said: "This dispute has been dragging on for many months and management should be in no doubt as to RMT's determination to achieve 12-hour rosters for our members.
"A 100% vote for strike action plus a near-100% vote in favour of a 12-hour roster system cannot and should not be ignored.
"This dispute has been ongoing for far too long due to management intransigence and it is a tribute to the determination and solidarity of RMT members that they have stood firm and are now geared up to support the next period of action in this latest in a series of strikes.
"We are now in the process of consulting signalling members across Scotland on the implications for the wider workforce of management's refusal to negotiate a reasonable settlement within existing rostering agreements.
"Our members have shown their anger through their rock-solid support for the earlier waves of strike action with pickets out in force sending a clear message to the employers that RMT is determined to win this fight."
Signallers in Stirling are understood to work around five eight-hour shifts a week. The union proposes that shifts be lengthened to 12 hours but that each signaller works fewer days each week.
Signallers at Stirling Middle, Stirling North and Dunblane will strike.
Mr Crow said the union is available for "meaningful" talks.