Security staff armed with truncheons will be on patrol on the Luas from now on to combat antisocial behaviour.
Both the red line from Tallaght to the Point and the green line from Sandyford to the city centre will be manned by security guards each evening from 4pm.
Luas operators Veolia said they have increased security to combat vandalism, loitering and intimidation on the light rail system.
"There has been an increase in antisocial behaviour in the city centre in the past year and this has affected our service," said Veolia spokeswoman Dervla Brophy.
The new security teams, supplied by security company STT, will be armed with truncheons. They will also wear stab vests underneath their black uniforms.
Labour transport spokesman Tommy Broughan has raised the issue of security repeatedly in the Dail.
He also produced figures which show how drivers and inspectors have been subject to repeated assaults.
"In July, nearly 200 attacks on drivers and inspectors were reported over an 18-month period," he said. "It is not acceptable that Luas commuters or staff would be subject to ongoing harassment of any sort. Luas security measures clearly need to be reviewed.
Mr Broughan told the Herald that the added security was a reflection on our society.
"The fact that we need security staff on the Luas is an indictment of the level of thuggery out there" he said.
Dervla Brophy said Veolia and STT will continue to liaise with gardai on security.