Iarnród Éireann has said that a full DART service will be in operation by tomorrow morning along with a significant improvement this evening.

It follows severe overcrowding on the DART network this morning after drivers refused to carry out so-called "coupling checks" when more than two carriages are joined together.

Drivers with trade union SIPTU told the company that this check was a maintenance function and they have ceased carrying out the checks.

Speaking on RTÉ’s Morning Ireland, Iarnród Éireann spokesperson Barry Kenny said the problem was worse for commuters trying to board trains at stations closer to the city centre.

He said that some supplementary services were being operated but these were also two-carriage trains.

There was also no transfer of DART tickets for use on Dublin Bus.

Iarnród Éireann has said that the vast majority of passengers will see a full service this evening but that, in a small number of cases, some DART trains will be shorter than normal.

Talks between management and drivers will take place tomorrow.

SIPTU organiser Paul Cullen said: "SIPTU members have been carrying out the test on a goodwill basis since 24 September when we informed management that drivers would not continue to carry out maintenance work indefinitely.

"We are hopeful that discussions with management can lead to an early resolution of this dispute and prevent further disruption of DART services."