Motorists are told to expect traffic today (January 3) anticlockwise between junctions 25 in Waltham Cross and 23 by A1M, with only one lane of the motorway open.
This is due to a crash between a heavy goods vehicle and the central reservation barrier last night (January 2) at 6.50pm.
Damage from the incident means the barrier needs to be replaced and the road resurfaced.
The incident happened where one lane had already been closed for long-term roadworks, leaving only lane two out of four open to traffic today.
National Highways says “significant delays are expected” and has told motorists to allow more time and to avoid the route if possible.
Repairs are scheduled to take place tonight.
