Smart Motorway gantry sign
A gantry structure spanning the motorway with electronic signals, blue signs showing the left two lanes exiting and the other two continuing ahead, and the following text.
Left-hand two lanes destinations: M25; [Solid square diversion symbol] (M4, M1); Heathrow [Airport symbol]; Watford .
Right-hand two lanes destinations: (M20, M11); Dartford Crossing M25 .
Change Route: M25 Heathrow or M25 Dartford
The mammoth four-lane sliproad divides - two lanes clockwise, two lanes anticlockwise.