More than 500 angry people had to queue at Lurgan and Portadown train stations after signal problems caused major delays.
Several irate passengers have complained of the major delays and the lack of communication.
Former Sinn Fein councillor Liam Mackle said the delays meant he would be two hours late for work.
Translink said: “Due to a major signalling failure there is a bus substitution in operation between Lisburn and Portadown in both directions until further notice.”
And the firm suggested that where possible people make alternative travel arrangements as delays can be expected.
However Mr Mackle said that alternatives are not an option for most people.
He said that when he arrived for the 8:26am to Great Victoria Street, Belfast, there were about 300 in the queue.
“In total far more than that loads of people get the 8:06, 7:46 for work in the city,” he said.
And that was just Lurgan. Portadown has also been affected by the delays.
“There weren’t enough buses on to prevent any long delays.
“I am going to be at least two hours late for work,” said Mr Mackle who also complained at the ‘very poor communication with those standing waiting for the few buses that were running’.
Another furious passenger said: “I have been at Lurgan station for an hour due to the delay. No buses, no queue system, People queued back to the car park in this weather.
“It’s like a refugee line up. Not even a joke.
A Translink spokesperson said: ““Due to a major signalling failure there is a bus substitution in operation between Lisburn and Portadown in both directions until further notice.
“Rail tickets will also be accepted on bus services between these two points.
“Where possible passengers are advised to make alternative travel arrangements as delays can be expected.
“Translink apologise for any inconvenience caused.”