Commuters are advised to check the Irish Rail website, as there are now extra services operating from nine stations nationwide - including Charleville.
The of changes came into effect overnight.
Irish Rail's Barry Kenny says the move is due to demand:
"The major changes centre around extra services from Newbridge to Houston, extra services through the Phoenix Park Tunnel route, and extra services from places like Ballina, Kilcoole, Kilkenny and a number of services around the network, basically matching demand as we see growing in different areas and different parts to serve people who are moving to rail".
