The safety and security of railway tunnels is an operational matter for Iarnród Éireann and I have, therefore, no function in the matter.
However, I understand from Iarnród Éireann that fencing is used to deter trespass on the railway and signs are erected warning against trespass. I am also advised by Iarnród Éireann that all railway lines are patrolled on a regular basis by the permanent way inspectors and persons caught trespassing on the railway are prosecuted.
Question No. 62 answered with Question No. 44.