"Multiple points failures" led to widespread train cancellations across Scotland on Wednesday night.
No services were running in or out of Glasgow Central station's high level and all Ayrshire trains were affected.
Other services were cancelled, suspended or delayed as Network Rail engineers worked on a fault with the air pressure on the points motors.
ScotRail said most services were now running as normal but a few early morning trains had to be cancelled.
This was due to the disruption leaving some trains away from their scheduled departure points.
The routes affected on Wednesday included Glasgow to: Paisley, Shotts, Motherwell, Cathcart, Newton, Gourock and Wemyss Bay.
The fault was initially blamed on high temperatures but Network Rail later confirmed it was due to a loose air hose on the air-driven points.
ScotRail arranged for passengers to be able to use their tickets on local bus services and said some customers would be entitled to compensation.
On Wednesday, a ScotRail Alliance spokesman said: "We sincerely apologise to customers affected by this disruption and completely understand their frustration when these things happen.
"We are doing all we can to reinstate services as soon as the signalling faults are resolved.
"Anyone delayed by 30 minutes or more is entitled to compensation under our Delay Repay Guarantee. To claim, simply keep hold of your ticket and visit our website or mobile app."