There were five-mile queues on the M25 after a closure of the Dartford Tunnel following a spillage.
Both tunnels were reportedly shut for 40 minutes from 9.30am but have since reopened.
The resulting congestion at one stage stretched back to Junction 3 at the Swanley Interchange.
It was not helped by a vehicle breakdown in the queues, which led to the closure of two lanes.
As of 11am, Highways England's traffic cameras showed there was still heavy traffic in the area but the delays were easing.