Irish Rail had reports of cocaine, ketamine and other drug use on trains last year.
They are among 277 anti-social behaviour complaints the company received in 2021, up 7 per cent on the year before.
One woman says she travelled on the Dublin to Cork train last November with her husband and young son. She says there was a man sitting across from them taking cocaine for the entire journey.
Last September a complaint was lodged about two men taking ketamine on the Dublin to Belfast line.
Several complaints relate to drunken and aggressive behaviour, and people not wearing face masks.
On the Belfast train, it's claimed a woman was 'intimidated' and 'preyed' upon by a group of drunk men. On another train, there was a complaint of a drunken man threatening to punch and kill everyone on the train.
Dermot O'Leary, the General Secretary of the National Bus and Rail Union, says dedicated transport police are needed to tackle the problem.
But Junior Transport Minister, Hildegarde Naughton, has ruled that out;
"No, there are no plans. I think this cross agency, every agency working together, is the way to do it. Our public transport operators, our employees, the security on-board Irish Rail."
She says a new security monitoring centre has played a key role in targeting high-risk locations.
Irish Rail says it works extensively with other agencies, including the Gardaí, to combat antisocial behaviour.
