A lorry is on its side after overturning on a slip road near Hemel Hempstead.
Herts Police were called to the incident at 11.16am after a Ford flatbed Transit overturned on the southbound carriageway at Bourne End services.
No one was trapped in the vehicle and the driver is uninjured.
Two fire engines and a number of police cars remain on scene while vehicle recovery is being arranged.
It is believed the traffic remains free-flowing but there is currently no access to the services.