Smart Motorway gantry sign
A gantry structure spanning the motorway with electronic signals, blue signs showing a "tiger tail lane drop" where the left lane exits, the right hand two lanes continue ahead and the second lane from the left can go in either direction, and the following text.
Exit destinations: A1(M) Hatfield; A1 London (N & C); A1081 Barnet.
Forward destinations: (M1, M40, M4), St Albans (A1081); Watford, Heathrow [Airport symbol] M25 .
Junction number: 23.
Change Route: A1 London & Hatfield
There's a big gap between the carriageways of the M25 just here where the motorway was meant to continue south west towards Bushey. In the end a very different route was built. At junction 23 we cross from one of the oldest parts of the route to the very last part to open, J19-23, which completed the circuit in October 1986.