The CEO of the National Transport Authority has said 2019 saw the largest increase ever in public transport users, with a 9% rise in passenger journeys.
Speaking on RTÉ's Drivetime, Anne Graham described the increase as "phenomenal".
She said to see such an increase would be cause for celebration in other jurisdictions, but said there was "no doubt" that this was leading to congestion on services.
"We are actually a victim of our successes, in that people do want to use public services, but we have work to do in trying to increase the capacity of some of our fleets to be able to meet this increased demand," she said.
Ms Graham said more investment was needed in infrastructure to reduce journey times and to improve the public transport system.
She urged people who use peak commuter services, and who may have flexibility, to take earlier or later trains or trams in order to have a less congested journey.
She also said a reduction in off-peak fares did not encourage people to travel at off-peak times.
Ms Graham said this was already implemented and the experience showed that lower fares did not act as an adequate incentive for people to travel off-peak.
Ms Graham was speaking after one Irish Rail commuter described his journey this morning as "pandemonium".
Roy Scott told RTÉ's Liveline that the 7.45am train from the M3 Parkway to Dublin's Docklands was "so full that women were trying to push buggies into walls of people".
He said the train was packed to capacity within one stop, but it had nine more to make before its final destination.
Mr Scott has been using the same service for the last four months, but likened his journey to "hell on earth" since the return to work in January.
He described the increase in the apparent number of service users as "unacceptable".