Rail passengers have been warned to expect cancellations and delays on services for the rest of the week ahead of further strike action by workers.
Members of the RMT union will walk out for the third time in the space of five days tomorrow in a bitter argument over pay, jobs and conditions.
Around 40,000 employees already undertook industrial action on Tuesday and Thursday this week during the battle with Network Rail.
A third strike is planned for Saturday, however the staggered reopening of signal boxes in some areas outside the central belt means those planning travel on Friday and Sunday may still find journeys cut.
RMT members have been offered a 3% pay increase by the operator, but raised serious concerns over plans to cut jobs and change working conditions under an “efficiency drive”.
Staff say they also want a wage increase to reflect soaring inflation, with rates set to hit 11% later this year.
Around 90% of trains on ScotRail routes have been cancelled, while cross-border links have also been badly affected.
Network Rail said stations including Edinburgh Waverley were around 20% quieter than usual while broadband provider Virgin Media O2 said “millions more” people were working from home after recording a 10% increase in usage during the week.
ScotRail has warned the disruption could continue until next week.
RMT assistant general secretary Eddie Dempsey said it was “time Britain had a pay rise” after real-terms reductions in wage packets for over 30 years.
He said: “It’s a scandal that billions are being ripped out of our industry at the same time workers are being punished.
“Teachers, they’re facing a cost-of-living crisis, (also) posties, telecoms workers, health workers.
“We think there’s going to be more demands for increases in pay in the economy and we think that’s right.
“It’s about time Britain had a pay rise. Wages have been falling for 30 years and corporate profits have been going through the roof.”