Rail services between Belfast and Dublin were expected to return to normal today after work to repair a collapsed viaduct was completed ahead of schedule — spelling good news for thousands of passengers after months of disruption.

Translink has announced a slashing of fares on the cross border Enterprise service to entice back thousands of travellers who abandoned it after the Malahide railway viaduct near Dublin collapsed into the sea in August.

Bus transfers have been in place between Dublin and Drogheda since the bridge fell into the sea moments before a Belfast passenger train was due to travel over it.

An Iarnrod Eireann spokesman said full Enterprise services will be restored today, but warned trains can only travel at a limited speed for a while.

Iarnrod Eireann operates rail services on the Republic’s side of the border ,while Translink has responsibility in Northern Ireland.

Test trains have been operating on the route ahead of this morning’s first passenger train being allowed to pass over.

Recent Translink figures showed that the number of passengers travelling on the Enterprise train had dropped 60% since the track collapse. It is estimated that between £1m and £2m could be lost in revenue because of the disruption.

Catherine Mason, Translink group chief executive, said the transport company was offering “exceptional value low fares”. However, they will not be introduced until Saturday.

Among the slashed fares being offered are single Enterprise ticket for £4.99, a day return for £7.50 and first class day return ticket for £25.00. Promotional fares will be offered until January 3.

Conall McDevitt, managing director of Weber Shandwick, which has offices in Belfast and Dublin, welcomed the reopening.

“It has been a huge inconvenience, making it much more difficult to move staff between our two offices.”