The Dartford Crossing had to be shut in both directions at the weekend because of a suspect package.
Police were called on Saturday evening, and decided to halt traffic in order to investigate.
They discovered the package was harmless.
Drivers using Twitter described the delays as "severe", however a spokesman for Highways England said, "the road was never fully closed but traffic was held temporarily, it was a fairly quick and easy police incident."
The road remained closed for around 30 minutes while the safety checks were carried out.