Bus transfers are going to be in place today for train commuters between Dublin's Heuston station and Waterford.
It is so Irish Rail can upgrade a signalling system at Kilkenny Station and to allow for Sallins bypass works.
There is going to be a revised schedule for all services from today to Easter Monday.
Iarnrod Eireann spokesperson Barry Kenny says passengers from Heuston to Newbridge will also be affected.
Mr Kenny said: "We're also starting works between Heuston and Kildare for Kildare County Council to provide an underpass, a bypass road scheme.
"So from today through to lunchtime on Easter Monday, all intercity services to and from Heuston will have bus transfers for part of the journey between Heuston and Newbridge or Kildare."
There are also engineering works tomorrow and Sunday between Dublin Connolly and Rush/Lusk which means that there will be no DARTs operating between Howth, Malahide and Dublin Connolly.
Bus transfers will operate on the Enterprise service between Dublin Connolly and Drogheda and there will be bus transfers on Northern Commuter Services between Dublin Connolly and Skerries.
On the roads, Gardaí will be cracking down on anyone who drives under the influence of drink or drugs this weekend.
Extra checkpoints will be in place across the country.
The Transport Minister Shane Ross wants to see a repeat of the Easter weekend last year, when no lives were lost on the roads.