Irish Rail conceded that “thousands” of commuters were affected by a signal failure at Heuston Station today which was described as the “worst fault” the railway experienced in years.
The company said the volume of passengers affected ruled out the possibility of providing a substitute bus service for customers.
“Thousands and thousands are impacted, there wouldn’t be a sufficient number of buses in the country to transport those passengers,” spokesperson Jane Cregan told RTÉ radio’s Morning Ireland.
Speaking on the same station later, Ms Cregan said a software error was responsible.
She told the News At One that the length of delays as a result of the signal failure was half an hour or less by lunchtime.
“There’s a number of software systems that run on the signalling system, there’s been a problem with one of the software programs that runs that system,” Ms Cregan said.
A manual signalling system was put in place across the country while the problem was addressed.
Spokesperson Barry Kenny said Irish Rail will work to “understand what happened to ensure we can prevent it happening again”.
"It certainly was the worst fault that we've experienced in quite a number of years in terms of severity, the time that it happened and the impact on services,” he said.
Services in and out of Connolly Station were not affected.