Trains have been delayed or cancelled at Glasgow Central following a signalling system fault.
Lines into the station have since been reopened but disruption is expected until 2.30pm.
The disruption comes as ScotRail reinstated its full timetable on Monday, following a pay dispute with train drivers.
A quarter of services were axed in July as the rail operator sought to provide a “reliable” service in the face of crew shortages.
Last month, members of the ASLEF union voted in favour of accepting a new pay day, with an uplift of 4.5% dated back to April 1.
It was also announced by the operator that they will be making slight adjustments to the timing of services across the network due to leaves on the lines.
ScotRail said the “majority” of services will be unaffected but that customers should check before travelling.
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