The Queen Elizabeth II bridge at the Dartford Crossing was closed on Tuesday morning after a suspected WWII bomb was discovered at the site.
Traffic was disrupted as the M25 bridge was shut after the ordnance was found at a nearby industrial site, just before 9am UK time.
However, after assessing the bomb, a military bomb disposal team confirmed that it was an empty shell casing with no explosives inside.
The bomb is not the same one as was found at London City Airport on Sunday evening.
Bomb disposal teams were also called to Worthing beach on Monday when a 'suspicious canister', which could have been an unexploded depth charge, was found.
That section of the beach has now been closed off to the public.