Trams are testing out the new Luas Cross City route in Dublin city centre.
Following four years of construction, trams kicked off at 7am this morning at slow speeds from five to 10 kilometres.
The new line connects the north district to the south and is expected to bring in an additional 10m passengers a year once up and running from December.
The tests - called guage run tests - will see the trams travel from St Stephen's Green to College Green and on to O'Connell Street.
Dublin Town CEO Richard Guiney says footfall continues to rise in the city and the infrastructure needs to meet consumer demand.
"It is good to see that investment. We'd like to see more investment in public transport," he said.
"That is the way things are going and young people will definitely use public transport if you get WiFi on that public transport. That's an international experience so we do have to invest in our public transport.
"Dublin is going to continue to grow, we will be a city of two million people."