M25 lane closure causing delays (Image: Archant)
There is nine miles of congestion on the M25 due to a car and a heavy goods vehicle crash near Potters Bar.
Lane one of the motorway clockwise between Junction 24 for Potters Bar and Junction 23 for Souths Mimms has been closed.
Highways England is advising it will add 45 minutes onto usual journey times.
It is also advising drivers to approach the scene with caution.
Normal traffic conditions are expected between 4pm and 4.15pm.
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