Smart Motorway gantry sign
A gantry structure spanning the motorway with electronic signals, blue signs showing the left lane exiting and three others continuing ahead, and the following text.
Exit destinations: A1 London (N&C) A1(M) Hatfield; A1081 Barnet; Services.
Forward destinations: (M11, M20), Potters Bar (A111); Stansted [Airport symbol] Dartford Crossing M25 .
Junction number: 23.
Change Route: A1 London & Hatfield
South Mimms is a formidable junction - the M25 and A1 cross paths here, and between them is a huge roundabout, one of the UK's largest, with multiple lanes and traffic lights all the way round. Six roads meet there, plus a motorway service area. Navigating it can be a whole day out in itself.