Grand Central Station Belfast: No date set for trains running

To facilitate the changes, the train track between Belfast and Lisburn has been closed for the summer.

This closure has also affected the cross-border Enterprise service, which is running bus substitution services between Belfast and Newry.

Mr Curry told BBC News NI that the disruption was a “big logistical challenge”.

He said there would be an enhanced, high frequency bus substitution service on the Lisburn to Belfast route as pupils return to school.

Mr Conway was also asked about the disruption which will continue into the new school term in September.

“It’s the largest infrastructure project on the island of Ireland and therefore needs careful management as we move to the opening phases,” he said.

“We’ve laid over 6km of new track. We’ve implemented a brand new digital signalling system and a new contactless system with automatic gates and barriers.”

Mr Conway explained that all of the new equipment required testing and training for railway workers.

“But most importantly we have a safety authorisation process to go through and the safety authority have to have their say on that,” he added.

“Therefore we’re doing a phased opening to make sure it’s safe for everyone and to make sure everyone gets used to the new facilities.”