Irish Rail is banning alcohol on a number of Friday services from today following complaints of anti-social behaviour.
Three services from Heuston to Galway and one from Heuston to Westport will be affected.
The company says it follows feedback from customers and staff about issues aboard these services.
Barry Kenny from Irish Rail explains why they've taken this step.
"This is simply in reaction to feedback from our customers and our employees because of some issues with anti-social behaviour on these trains fuelled by alcohol and we really do have to act when we have a regular pattern of anti-social behaviour of this type," said Mr Kenny.
Irish Rail says it will not rule out introducing the measure on other services if problems arise.
"We hope that everybody will follow the example of the vast majority and if they are having drinks will do so responsibly and without causing any irritation or annoyance to other customers," said Mr Kenny.
"We will act if we see patterns of anti-social behaviour that is making other people's journeys unpleasant.
"It's the majority that we are looking after here."
The ban on alcohol is being introduced on the Heuston to Galway routes departing at 11:25, 13:25 and 15:35; as well as the 14:45 train from Heuston to Westport from today.