The M25 has been shut after a serious collision involving a crane that overturned and crashed over both sides of the carriageway.
The incident happened at Junction 27 with the M11 in Essex on Friday evening around 5.30pm.
It has caused huge tailbacks in both directions including more than 10 miles on the clockwise carriageway.
Anti-clockwise, the carriageway is currently closed between junctions 28 and 27 with traffic congestion back to junction 29.
Essex Police confirmed no-one has been seriously injured but added the road is likely to be closed for “some considerable time.”
Highways England has also warned motorists to avoid the area while the emergency services work to clear the scene.
Pictures shared on social media show an unknown liquid coming from the vehicle and covering parts of the road.
Several blocks from the carriageway have been broken off by the crane and spread across the junction, making it impossible for cars to pass.
Highways England has said the incident is also causing congestion on the M25 clockwise between junction 25 and 27, adding at least 80 minutes to normal journey times.
In a statement, Highways England said: “Specialist contractors will be required to recover the vehicle. The road is likely to remain closed for some time whilst this work continues and will re-open as soon as it is safe to do so.
“For traffic approaching the delays locally, drivers are advised to expect disruption with extra journey time and may wish to re-route or delay their journeys.
“If travelling towards this area from much further afield, delay information will remain visible on on-road variable message signs until delays have cleared.”