Irish Rail has condemned a teenage dare which involved a boy lying beneath a section of railway track while a train travelled over it at 90mph.
A video, which was uploaded to the Bebo website, showed the young man crawling underneath a railway sleeper and waiting for the train to pass while being filmed.
The video is believed to have been made near Monasterevin, Co Kildare, but Irish Rail could not confirm the exact location.
Barry Kenny of Irish Rail described the incident as "reckless behaviour". He said it was "miraculous" that the young man had not been killed.
Irish Rail said it was very relieved he had not been injured during the incident.
"The young man clearly didn't understand that when a train travels over track it causes it to move and he could easily have been killed, crushed or badly injured," Mr Kenny said.
This is the first instance of such behaviour that has been brought to the attention Irish Rail and Mr Kenny said he hoped it would be the last incident of its kind.
The video was uploaded to Bebo.com, an online social networking community where people chat, share videos and photographs and make new friends. The service is very popular among students and young people. Irish Rail was made aware of the video by a journalist and immediately contacted Bebo to have it removed. The video is no longer available for viewing on the website.
A profile of the teenager who published the video accompanied it on the webpage and Irish Rail confirmed it has made contact with the Garda about investigating the incident.
Mr Kenny said the identity of those in the video is very clear and he believes the people involved are 15-18 years of age.
This is not the first controversial item to have been published on a social networking website. "Happy slapping", a game where people attack others at random, made the headlines last year following the publication of videos in similar circumstances.
"I've seen pages where groups of hooligans arrange fights and others where people publish videos of self abuse," Robert Billington, a Bebo user said. "The content people upload to these websites is largely unrestricted and will remain in place until someone complains about it," he said.
