Irish Rail says it may have to introduce more 'pre-book only' services in the future as more people use the train.
The travel company says the practice is already in place for big events like All Ireland final days.
Passenger numbers are currently at record levels but new carriages aren't expected until at least 2021. There were 48 million journeys in 2018.
However Irish Rail spokesperson, Barry Kenny, says it won't become a feature on regular services;
"We are in that point between when we're expecting imminent approval from government for an order for new carriages but it will be two years until those carriages arrive. So it is something we would have to consider looking at for more events. It's not something we anticipate on a general basis."
The company recently introduced a new website to get more people to use less busy DART services in a bid to overcome overcrowding.
