Tourle Street Bridge at Kooragang has re-opened around 5.40pm after an earlier police operation Tuesday afternoon.
A number of officers were on the scene conducting a search of the area after witnesses reported a 4WD vehicle was stopped in the roadway around 2pm.
Northbound lanes were closed for several hours. Southbound traffic was unaffected, Police said in a statement posted to social media just after 3pm.
Drivers travelling north were told to avoid Tourle Street and go via Hexham on Tomago and Cabbage Tree Road.
Lifeline: 13 11 14
