The Enterprise Express train from Belfast to Dublin was delayed by 20 minutes yesterday morning following protest warnings by the ILDA.
Threats to block the line did not proceed, according to Iarnrod Eireann, although a number of ILDA members gathered near the railway close to Skerries, Co Dublin. They had dispersed by the time gardai, who were called by the company, arrived. Three other ILDA members were seen close to the line at Dunleer, Co Louth.
A spokesman for the company said the ILDA's actions were a breach of their "supposed concerns for safety".
However, an executive member, Mr Finbarr Masterson, said: "No experienced railway man would endanger himself or anyone else and they did not."
According to an Iarnrod Eireann spokesman, the driver of the 7.40 a.m. train from Belfast drove at a very slow speed following a call by an ILDA executive member, Mr Tony Collier, to the station at Drogheda that there would be a protest.
North of Skerries, near Lady's Stairs close to Ardgillen, a number of ILDA members gathered but dispersed before gardai arrived.
Another member of ILDA telephoned a staff member at Dundalk station and said there would be a "peaceful protest" at Dromiskin, south of Dundalk station.
The ILDA member and two others were spotted by the driver near the line at Dunleer but did not attempt to block the train.
The Iarnrod Eireann spokesman accused ILDA of being "vindictive" in having another protest by the railway line at Claremorris, Co Mayo, when the company was trying to restore a service. However, Mr Masterson said this was also a "peaceful protest" and there was no disruption of the service.
