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: M20 [Hollow triangle diversion symbol] ; Dover; Channel Tnl; Maidstone.
Forward destinations: A20 London (SE), Swanley; Bromley (A21), Gatwick [Airport symbol] (M23); (M3) Heathrow [Airport symbol] (M4) M25 .
Junction number: 3.
There's two parts to junction 3 - this first one is a set of direct sliproads to the coastbound M20. In a moment you'll have another shot at junction 3 which is the way to the A20, Swanley and Brands Hatch.