Both lanes of the Dublin Port Tunnel have re-opened after a safety systems failure lead to the tunnel being closed for most of the day.
A team of contract specialists worked through the day to correct the problem.
The National Roads Authority says it will carry out a full investigation to determine the cause of the systems crash.
The ban on heavy goods vehicles in the city centre was temporarily lifted because of the incident.
AA Roadwatch reported heavy traffic on most routes in the city centre earlier today as a result of the closure.
