A signalling system fault has caused major disruption to trains operating on routes between Glasgow and Edinburgh.
There were cancellations to services between Glasgow Queen Street and Edinburgh and Edinburgh to Dunblane and Stirling.
Routes from Glasgow to Helensburgh were also badly affected. ScotRail blamed a fault with the signalling system between Edinburgh Park and Linlithgow.
Disruption continued on Friday evening while engineers worked on the fault.
A ScotRail spokesman said: 'We are sorry to customers for the disruption to their journey, which was caused by a signalling fault.
"Network Rail engineers are working hard to fix the fault and we are doing everything we can to keep people moving.
"Customers are asked to check @ScotRail on Twitter or the ScotRail app for the most up to date information.'