Two lanes are closed on the A1(M) after a three-car crash near Welwyn, and traffic is solid all the way back past Stevenage to Letchworth Gate.
Police were called to the crash on the northbound carriageway near Junction 6 for Welwyn amid the heavy fog at about 8am, with ambulance crews also attending.
Two lanes are blocked, with vehicles awaiting recovery. Herts County Council’s Highways department predicts delays of up to 54 minutes.
Police were unable to confirm details of any injuries. An ambulance service spokesman said paramedics were stood down as they were not needed at the scene.
Separately, traffic on the southbound stretch is solid from Junction 7 for Stevenage back to Junction 9 for Letchworth Gate.
There are also delays of up to 20 minutes on the A602 Park Way in Hitchin, according to the county council Highways team.
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