A car has hit a water main on the southbound A1 Barnet Bypass, which has closed two lanes in the area.
Delays are still affecting traffic from the A1 southbound, between the South Mimms exit on the M25, and the junctions with the A5135 and A1(M).
The ruptured a water main has also flooded an electricity sub station.
Herts Fire and Rescue and BCH Road Policing is working on fixing it and says there are still lots of hazards in the area.
They also advise that motorist avoid the A1 for now.
Highways England expects normal traffic conditions to return before 2.45pm.
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