Irish Rail is proposing that the Dart line be extended to commuter towns using hybrid trains.
The trains would run on overhead electric wires or diesel engines.
It would allow the Dart service to go as far as Maynooth, Co. Kildare and Drogheda Co. Louth.
The trains would use electricity closer to Dublin city, switching to diesel engines in the suburbs.
Iarnrod Eireann Spokesman Barry Kenny says capital investment is needed for the plan to go ahead; "We have put forward proposals for considering under the governments capital programme review to have over a 10 year period an order of 300 carriages to meet the demand and to cater for future electrification."
He added: "So that will be over a 10 year period but certainly we feel there is a need to confirm in a relatively short time frame 100 carriage order so that we can meet the demand that's there."