The discovery of a suspicious object during a hoax security alert in Newtownabbey, Co Antrim forced the temporary closure of the M5 on Tuesday night.
The Roads Service said the motorway was closed in both directions for a time due to the alert.
Police conducted searches after receiving a report that a device had been left in the Shore Road area.
A PSNI spokesman said army bomb experts examined the object, which they described as an "elaborate hoax".
All roads have now reopened. The security alert is over.