Commuters will now have to pay €2 per day or €8 per week for parking at a number of stations along routes in Louth, Meath and Dublin.
The stations where the new parking regulations were introduced are Dundalk, Drogheda, Laytown, Balbriggan, Skerries, Rush and Lusk, Donabate, Malahide and Portmarnock on the northern line.
It is expected that the pay and display system will commence at over 20 other stations in the coming months.
Meanwhile, barrier-free tolling on the M50 in Dublin was put to the test this morning on its first weekday of operation.
There were no reports of any delays on the motorway and the new system did not seem to be posing any problems.
Motorists can no longer stop to pay at the toll plaza, which has already been partially dismantled.
Drivers must now pre-register their vehicle or pay the toll charge at a paypoint just before or after they travel.
