Belfast traffic lights glitch lead to major disruption
Problems with 29 sets of traffic lights in Belfast city centre led to traffic jams and tailbacks for morning commuters on Thursday.
A fault at a BT exchange meant there were problems co-ordinating the lights.
Although the lights were working, Traffic Control Centre lost the ability to manage them.
BT repaired the fault and traffic returned to normal. New bus lanes launched recently in Belfast were already causing delays for motorists.
At that time, Stormont Transport Minister Danny Kennedy said the system needed time to settle in.
John Irvine of the Department for Regional Development apologised for Thursday morning's traffic disruption.
A BT spokesperson said: "A fault developed in exchange equipment which had an impact on the level of service BT currently provides to DRD.
"Engineers completed the repair, normal service has been restored and a review will be conducted with DRD to help prevent a re-occurrence."
The Roads Service will now review its system to ensure it is robust.
Mr Irvine said he had confidence in the system.