Dart users are angry at Irish Rail over timetable changes which will see fewer trains stopping at three northside stations.
From next Monday, Darts are to run more frequently, meaning there will be a train every 10 minutes in both directions.
However, it means Dundalk and Drogheda services will no longer stop at Portmarnock, Clongriffin and Howth Junction.
This is to free up capacity for people living north of Donabate, but angry Portmarnock commuters are calling on Irish Rail to rethink the decision.
Irish Rail's Barry Kenny says it means there will be more chance of a seat for commuters at Portmarnock.
"All stations on the Dart network will see an increase in services overall. In Portmarnock it remains the same," he said.