Weekday commuters between Galway and Dublin are to experience considerable disruption to train services between the two cities.
This is due to a major improvement programme which Iarnrod Eireann is set to carry out on the line early in the new year.
More than £10 million is to be spent on the improvements, which will reduce the travel time between the cities to two hours and 20 minutes.
While the work is being carried out there will be no train service on weekdays between Galway and Ballinasloe for 10 weeks and passengers will instead be bused between the two stations.
"It is the only way we can do it, Mr Gerry Glynn, Iarnrod Eireann district manager, said yesterday.
"We plan to get in there, get the work done as fast as possible, and then we will have a continuous welded rail all the way from Dublin to Galway that will not need to be replaced for another 40 to 50 years," he said.
The disruption will begin on January 4th and from then until March 6th no trains will operate between Galway and Ballinasloe from mid-morning on Mondays until midday on Fridays.
A substitute bus service will act as a shuttle between the stations and, as a result, departure times from Galway will be 25 minutes earlier than at present.
The alternative arrangements will not mean any disruption to freight or Fasttrack services.
A total of £7 million is to be spent on upgrading 18 miles of track. A further £3.5 million will be spent on improved modern signalling, to replace the semaphore signals which have been in use since the 1850s.
The work is the first phase of a national investment of more than £100 million to be spent on upgrading Irish Rail services next year. Improvements are also to be made to the lines out of Sligo, Westport, Waterford, and Tralee.
It will be the biggest single annual investment in the State's rail network and it will be co-funded by EU Cohesion and Structural funds.