Up to 155,000 commuters are thought to be affected by a strike among Irish Rail workers.
Today's the first of five scheduled stoppages by staff at the company in a row over pay.
People commuting are being advised to leave extra time for their journeys - there's some extra private bus services running but demand is expected to be high.
Meanwhile, Dublin Bus and the Luas are NOT accepting valid tickets.
Services will resume tomorrow, before another day of industrial action on Tuesday 7th November.
Image credit: @SeanDefoe