Commuters who've managed to sneak away from work early today are in for a bit of strife in the city, with the Sydney Harbour Tunnel closed southbound.
An overheight truck is currently causing problems at the entrance.
Citybound traffic is being diverted onto the Harbour Bridge.
Traffic is reportedly already heavy, so motorists are advised to allow extra travel time and expect delays.
Emergency services and traffic crews are currently attending the scene.