Traffic is now flowing again on the southbound lane of the motorway through Green Island.
A 21-year-old student contacted police and told them he had attached five pinhole cameras to the Koremata St overbridge at Burnside to monitor traffic several days ago.
These were mistaken for bombs by a member of the public, triggering an alert.
By the time the student contacted police a bomb disposal team was already on its way from Christchurch.
Inspector Alastair Dickie, said police were still investigating whether charges would be laid.
Traffic was diverted from the southbound lane of the southern motorway out of Dunedin and some residents in the area were evacuated while the incident was being attended to. All affected roads are now open.
Dunedin Airport was closed for five hours yesterday after a hoax bomb device was left in the toilets.
