The DART has been described as a third world service for first world prices.
A Wicklow TD has carried out a survey, which shows almost 90% of passengers have recently been on a train they described as "dangerously overcrowded".
Irish Rail says the DART is designed to cater for full loading safely, and continues to do so.
Fine Gael Deputy, Simon Harris, has called for more carriages to be added to each train.
