The luas red line was not in operation this morning following an incident between a tram and a van near Blackhall place.
The north side rail service was in operation from Saggart and Tallaght to Blackhorse after the incident, when one tram was travelling inwards towards The Point.
There were no injuries involved. Luas tickets were valid on Dublin Bus as a result of the disruption.
It was fully operation once again at around 10am.
A Luas spokeswoman appealed to drivers not to take chances when approaching amber lights.
"People are gambling with the safety of Luas customers and their own safety," she said.
In 2013, there were 36 incidents between vehicles and Luas trams and 22 in 2012.
"It's not a good start to the year."