Dublin commuters who normally travel by train are advised to leave home in plenty of time this morning.
It's the second day of Iarnród Éireann strike action by SIPTU and NBRU members at the company.
Workers are rejecting pay cuts which Irish Rail say are essential for it's survival.
Further disruption is also planned for September 7th, 8th and 21st.
The LUAS will operate as normal, as will Dublin Bus services.
Jerry Murphy is CEO of The National Transport Authority.
Conor Faughnan from the AA says traffic isn't expected to be too bad this morning, as the schools aren't back yet.
But he says anyone whose commute takes them near a number of hotspots in Dublin should set out a little earlier than usual:
Three more days of disruption are still on the cards for September 7th, 8th and 21st.
Paul Melia, Environment Correspondent with the Irish Independent, says there's no sign of a compromise on either side of the row:
