Rail commuters travelling between Belfast and Dublin faced further disruption today as part of the track remained closed after a second night of violence in Co Armagh.
Northern Irish Rail stopped trains last night between Lisburn and Portadown after dissident republicans again whipped up trouble in Lurgan.
Rail passengers were being bussed between Drogheda and Belfast for services this morning.
Northern Irish Rail said it could not say when the line would reopen fully.
A number of vehicles were hijacked last night and attempts made to set them on fire and police urged people to keep away from the areas of Lurgan and Craigavon.
The trouble broke out just hours after the Police Service of Northern Ireland launched a major operation aimed at preventing dissident republicans going on the offensive.
It is understood the PSNI is intent on cracking down after receiving intelligence that the dissidents want to mark with violence the arrival from England of new Chief Constable Matt Baggott who takes over the reins next Tuesday.
The trouble in Lurgan followed violence which started on Thursday night after the jailing of three local dissident republicans for plotting to kill police officers.
During the first night of trouble more than five vehicles were hijacked and set on fire and police reported receiving numerous reports of armed men on the streets in what they said was clearly pre-planned and orchestrated violence.
There were also reports of armed men on the streets of Lurgan last night.