Irish Rail is promising to continually monitor the number of passengers taking the DART.
It follows a rising number of complaints about overcrowding.
Passengers on Intercity, urban and suburban routes have complained about the crowded carriages - which have been linked to reduced numbers of trains and carriages on certain routes.
Irish Rail insists that overcrowding is a comfort issue, not a safety issue.
Spokesperson, Barry Kenny, says commuters can't always expect a seat during rush-hour.