Nearly 30 trains were cancelled today and others disrupted following a signal fault in Motherwell, a key rail junction.
Passengers affected included football fans heading for the Celtic v Hearts game at Celtic Park in Glasgow.
Signalling and track problems have now plagued the network on four of the last five days.
ScotRail and CrossCountry services were among those affected today, with some passengers switched to buses and other trains diverted.
Rail sources said 28 trains which should have terminated, started from or called at Motherwell were cancelled - almost the station's full Sunday service.
It was caused by a fault with signal wiring preventing trains from leaving ScotRail's Motherwell depot.
ScotRail trains between Milngavie/Balloch via Glasgow Central to Motherwell and Lanark were worst affected.
CrossCountry trains between Glasgow and England via Edinburgh were also affected.
The disruption follows problems on the Aberdeen-Inverness line yesterday after a signal box did open because of shortage of staff, causing delays until 9:30am.
A points failure on Thursday at Newton, east of Glasgow, disrupted Edinburgh-Glasgow services via Carstairs, and there were signalling problems on the Inverness-Wick line.
The previous day, a points failure at Inverurie in Aberdeenshire delayed trains using lines between Inverness and Tweedbank in the Borders.
The ScotRail Alliance with Network Rail said today's fault was fixed about noon but disruption was expected to continue until 2pm because of trains and crew being out of position.
A spokesman for the alliance said: "Due to a signalling fault at Motherwell, services were disrupted this morning.
"We tried to keep customers moving by sourcing replacement buses and arranging for valid train tickets to be used of First Glasgow buses.
“Our engineers worked as fast as possible to fix the fault and return services to normal.
"We apologise for any inconvenience caused by this disruption, and remind customers delayed more than 30 minutes that they are entitled to compensation under our Delay Repay guarantee, provided they keep hold of their tickets.”