Dozens of train services have been cancelled after ScotRail reported a major fault on Monday morning.
By mid-afternoon, ScotRail announced that it had fixed the fault and that it was starting to reinstate services through Glasgow Central Low Level and on the Helensburgh and Balloch routes.
But, they warned that disruption will continue, with time needed to get trains and crew where they need to be.
It comes as thousands of Scots prepared to return to the office as a coronavirus restriction urging people to work from home was lifted on Monday.
Network Rail said fibre cable failure meant train drivers and signallers were unable to communicate with each other.
The fault meant dozens of commuter services were cancelled.
ScotRail reported that eight services were severely affected by the fault, with the company urging customers to check their journeys before attempting to travel.
Some replacement buses were put in place and tickets accepted on some West Coast and McGills buses.
Edinburgh Trams will also accept tickets between the city centre and Edinburgh Park station.
ScotRail said it was unclear when the issue would be fixed, with Network Rail saying specialist teams had been requested to fix the fault.
By midday, some services were running again however trains at Glasgow Central’s low level platforms were still unable to run.
Nerwork Rail tweeted: “As of 1130, engineers are still working to fix the fault to allow trains to run normally.
“We’ll keep you updated as work continues over the next few hours. We’re sorry for the impact this is having on journeys today.”
ScotRail said passengers who chose not to travel due to the fault could receive a full refund with usual fees waived and those who arrived late to their destination were urged to claim compensation.