Services on Dublin's Luas Green Line remain suspended this morning while repair works continue following a power failure.
The fault yesterday morning resulted in a loss of power to the Green Line and a temporary loss of power to a section of the Red Line, which has since been fully restored.
Luas operator Transdev said there are no services on the Luas Green Line from Broombridge to Brides Glen, with services not expected back in operation until after rush hour.
Engineers have identified that the fault lies within a critical low-voltage safety system known as the 48-volt system and not the overhead power system that powers the trams, it said.
Transdev Director of Communications Dervla Brophy said it is not yet possible to say when service will be restored.
There are currently 18 trams on the Luas Green Line.
These are all parked at Luas stops, with security deployed to each location.
Six trams will be moved this morning and early this afternoon, according to the Luas website.
Speaking on RTÉ's Morning Ireland, she said technicians were on site overnight and have inspected 12 sub-stations.
Ms Brophy said the issue has been identified as a fault with a safety circuit that controls the power from the sub-stations to the control room.
"We have narrowed it down from the area from Broombridge to O'Connell Street. We are working our way systematically through the Green Line and substations in order to restore power," she said.
Ms Brophy apologised to commuters said Luas will continue to provide updates on the Luas app, website and social media channels.
Transdev said in a statement this morning that the system is designed to shut down power to the overhead lines in the event of an emergency. The system is currently detecting a fault condition and, for safety reasons, will not permit the power to be fully restored until that condition is resolved."
It said Luas tickets are being accepted on Dublin Bus services.
'Major concern' for businesses
Around 72% of customers who shop in Dublin city come in via public transport, according to CEO of Dublin Town and member of the Dublin City Taskforce Richard Guiney.
He said that 15% of the customer base for the city travel by Luas and that the Green Line being down is definitely an issue.
"It is a major concern for city businesses," Mr Guiney said.
He said that Thursday is an important day for late night and the coming weekend is when things really start ramping up shopping wise, and so there is a need for resolution.
He said that people need to be facilitated to travel into the city by sustainable transport and that car parks are holding steady in the city, while outside the city, shopping centres are much more car dependent and they then see more issues there in terms of traffic and parking.
He said that he agreed with the idea of allocating space to cycle lanes away from general traffic and that businesses want to see more sustainable transport.
"We are not going to get where we need to be without the infrastructure, the likes of the Metro, and addressing issues like judicial reviews delaying things that we absolutely need," he said.
