Knock-on delays were expected on both the M1 and the M50
Gardaí say the Dublin Port Tunnel has re-opened after an earlier incident.
Emergency services attended the scene of an accident in the tunnel after a truck reportedly caught fire.
Dublin Fire Brigade say one patient was treated at the scene.
A tow truck was also brought on scene to remove the damaged vehicle.
The tunnel was closed to traffic in both directions for a time, but has since re-opened.
Dublin Port Tunnel has reopened and all diversions have been lifted. #m50safety— M50 Dublin (@M50Dublin) August 15, 2017
Additional reporting: Jack Quann