Scores of trains in and out of Glasgow Central were delayed or scrapped because of the signalling fault, which began affecting services before 4pm.
The travel misery affected thousands of passengers on the eve of the Commonwealth Games.
Scores of visitors have already began flocking to the city for the biggest sporting event ever held in Scotland.
Rail operator ScotRail urged passengers not to travel Glasgow Central today.
On their Twitter account, ScotRail staff said: "Please don't try to travel from Glasgow Central until further notice due to Network Rail signal problem.
"Services to and from Glasgow Central may be cancelled, delayed or revised at short notice."
Network Rail has now confirmed that the fault has been fixed but said that the delays were expected to continue, tweeting: "The problem at Central was due to an issue with an air compressor, this has been fixed so we are able to signal trains again.
"Considerable disruption will still be experienced though due to residual delays. Sorry for this."