Irish Rail have proposed introducing a number of extra services and has invited the public to give feedback on them.
The changes, which will start from 10 December if implemented, would see extra Cork, Carlow, Westport, Portlaoise, Mallow, and Drogheda services.
The operator is also looking at adding extra stops at Clara and Ballinasloe on some services, as well as others along the Dublin to Cork line.
One of the more notable proposed new services is an additional train from Dublin to Cork that would leave Heuston at 6am and arrive in Kent Station at 8.32am, from Monday to Friday.
If implemented, Irish Rail say it would be the first time that passengers would be able to arrive in the city from Dublin before 9am.
Two extra morning services between Cork and Mallow at peak times are also being proposed.
In Leinster there would be an extra 12.20pm train from Heuston to Carlow and 3.15pm service in the opposite direction, also running Monday to Friday.
In Connacht there is a proposal to establish a connection to and from Ballina to line it up with a new daily Westport to Athlone route.
The Dublin and Portlaoise route would see a "significant expansion" with 15 additional services, which would also benefit passengers traveling to and from Kildare.
Three additional routes from Dublin to Drogheda, and two from the Co Louth town back to Dublin are also being considered on a Monday to Friday basis.
In terms of journey times, the operator said it expects improvements on many to the Dublin to Cork and Dublin to Limerick services thanks to recent works.
It added that the new Kishoge Station will open in 2024 and will be served by local Heuston and Phoenix Park tunnel services.
The DART is also expected to see "significant" changes on Saturdays and Sundays which are being made to "improve performance" - this will help improve journey times for other services going to and from Connolly Station, Irish Rail say.
Public consultation is open until 27 September.
